WO2001066776A2 - Novel l-form bacterial strains, method for producing same and the use thereof for producing gene products - Google Patents

Abstract

Verfahren zur Gewinnung von modifizierten L-Form-Bakterienstämmen bei dem man (a) einen an ein komplexes Nährmedium adaptierten L-Form-Bakterienstamm alternierend bei unterschiedlichen Temperaturen im Temperaturbereich von 20 bis 40 DEG C kultiviert und (b) bei ansteigender hydromechanischer Belastung der Zellen fermentiert, modifizierte L-Form-Bakterienstämme, die gemäss dem Verfahren erhältlich sind, und deren Verwendung zur Herstellung von Genprodukten.

Description

 Novel L-shape ba strains, processes for their production and their use in the production of gene products

The invention relates to cell wallless bacterial L-form strains, methods for their production and their use for the production of gene products.

Artificially produced proteins are part of pharmaceuticals, foods, detergents and other substances and compositions that are essential for daily use. A large number of different methods are available today for the production of such proteins. In this context, the production of proteins in cell cultures is particularly important. The proteins produced in this way are referred to as recombinant. The production or expression of recombinant proteins is known in many different cell culture systems, also called expression systems, in the prior art. Depending on the type of cell used, a distinction is made between prokaryotic expression systems when bacteria are used as producer cells and eukaryotic expression systems when Eukaryotic cells from yeasts, fungi, plants or animals can be used as producer cells.

Despite the large number of known and used systems, numerous proteins, in particular membrane proteins, have hitherto not been able to be produced or can only be produced with unsatisfactory yield and purity. When using eukaryotic expression systems, the reasons for this lie primarily in the proteolytic degradation of the proteins produced by cell-specific proteases, in the frequently occurring toxicity of the foreign proteins for the producer cells and, in the case of membrane proteins, in the strong association of the proteins produced with the cell membranes of the producer cells. In addition, membrane proteins are only present in small amounts in the membranes and the membrane material is only available in limited amounts (e.g. in mammalian cells). The isolation of the membranes also usually requires material and time-consuming separation processes to remove disruptive structures such as cell wall, flagella, fimbriae and other membrane and cell organelles.

The production of recombinant proteins in prokaryotic expression systems has the disadvantage that the proteins frequently assemble into functionally inactive aggregates in the cytosol or periplasm, so-called "inclusion bodies". Furthermore, prokaryotic producer cells also have cell-specific proteases which can degrade the foreign proteins produced. In addition, when using E. coli as producer cells, toxic cell components, in particular components of the cell walls, often make it difficult to obtain protein preparations that are harmless to the consumer.

In order to overcome the disadvantages associated with the production of recombinant proteins in prokaryotic cells, the use of so-called L-shape bacterial cells has been proposed in the prior art. L-shape strains are bacteria that grow with a greatly changed or without a cell wall. According to the nature of the cell envelope and its stability, L-form bacterial strains can be divided into four groups. Spheroplastic T p L forms still have remnants of the cell wall, for example the outer membrane, while protoplast type L form cells are only surrounded by the cytoplasmic membrane. Cells that only remain in the L-form phase under constant selection pressure with the help of inhibitors of cell wall biosynthesis (for example ampicillin) are called unstable L-forms. Strains whose cells have completely lost the ability to form a cell wall are referred to as stable L-forms.

The conversion of ordinary bacterial cells, so-called parent bacteria, into L-form cells is known per se (J. Gu pert and U. Taubeneck, 1983, Experientia Suppl. Vol. 46 227-241; LH Mattmann, 1993, Cell Wall Deficient Forms , CRC Press, Boca Raton.

Here, cells of a bacterial type are first converted into spheroplasts or protoplasts by treatment with substances which inhibit cell wall biosynthesis (e.g. β-lactam antibiotics, vancomycin, D-cycloserine) or which break down the cell wall (e.g. lytic enzymes such as lysozyme) , These cell-wall-defective cells are propagated on a suitable medium until typical L-form colonies are formed and transferred to L-form medium until growth as dense colonies is achieved.

A nutrient medium is a solution that contains a complex nutrient component, preferably freshly prepared meat extract, for basic supply with C and N sources, amino acids and ions, a growth stimulator, preferably yeast extract with essential vitamins and amino acids, an osmotic stabilizer to avoid cell lysis, preferably Sucrose or NaCl, a membrane stabilizer, preferably serum and divalent cations such as Mg ²⁺ , and a cell wall biosynthesis inhibitor, preferably contains β-lactam antibiotics such as penicillin (primary L-form medium).

A commonly used complex medium is L-form standard medium (LFS). LFS medium contains fresh meat extract with additives of yeast extract (0.5-1% w / v), horse serum (8-10% v / v), sucrose (6-10% w / v), penicillin (200-1000 U / ml), Bacto agar (1-1.5% w / v).

The abbreviation w / v stands for mass per volume, i.e. 10% w / v corresponds to 10 g per 100 ml. Unless otherwise stated, all percentages in the present description are w / v statements. The abbreviation v / v stands for volume per volume.

The meat extract is obtained by extracting 2 kg of beef with 4 l of water in a steam pot for 1 hour, then adding 0.3 to 1% Bacto Peptone and 0.5 to 2% NaCl to the filtrate and adjusting to pH 7.0 ,

Then you select stable L-shapes, i.e. those L-forms which have the ability to revert, i.e. lost to the resynthesis of the cell wall in the absence of penicillin. For this purpose, agar blocks with L-shape colonies of a culture are transferred in parallel to LFS agar medium with and without the addition of penicillin until only L-shape colonies grow on the penicillin-free plates and no more reversion takes place. These stable L-shape colonies are propagated until a dense colonization is achieved on the penicillin-free LSF agar plates.

The production of stable L-forms of E. coli is described for example by U. Taubeneck and E. Schumann in Zeitschrift für Allg. Microbiology, Volume 6, 1966, pages 341-343, and by P. mlrabiliε from U. Taubeneck in Zeitschrift für Allg. Microbiology, Volume 2, 1962, pages 132-156. The stable L-forms are then adapted to growth in a liquid LFS medium. This contains freshly prepared meat extract, (2-5%), bacto-peptone (0.5-1%), NaCl (0.5-2% w / v), yeast extract (0.5-1% v / v) , Horse serum (8-10% v / v) and sucrose (6-10%). For this purpose, agar blocks (2 x 2 cm) with plenty of colony noses are placed in 10-40 ml liquid LFS medium and incubated at 37 ° C with shaking. Optimization of growth in liquid LFS medium is achieved by continuously transferring the cultures (every 2-5 days) to fresh medium until the L-form cells grow to cell densities of 10 cells / ml over the course of 24 hours. Through continuous transfer and growth in fresh LFS medium with gradually reduced amounts of serum and sucrose, L-form strains, for example of P. mirabilis and E. coli, are selected in the course of 50-80 passages, even without the addition of serum and sucrose show good growth. These can then be adapted to growth in meat extract-free nutrient media by gradually replacing the meat extract portion of the LFS medium with other nutritional components defined in their composition.

Brain-heart-infusion- (BHI) -broth (BHIB), tryptic-soy-broth (TSOYB), Todd-Hewitt-broth (THEB) and L-broth (LB) are particularly suitable, defined, complex nutritional components for replacing the meat extract. The detailed composition of these nutrient components can be found in the company handbooks Merck-Medium, E. Merck, Darmstadt, 1992 and Difco-Mannual lOth. Edition 1984, Difco Laboratoris Detroit MI USA.

The known L-form strains often show unsatisfactory growth in this media for inexplicable reasons.

Gumpert et al. disclose stable L-shape cells that are based on the treatment of normal bacterial cells with cell wall biosynthesis inhibitors such as ampicillin and simultaneous osmotic stabilization. These cells no longer form and no longer form a periplasmic compartment no extracellularly detectable proteases (J. Gumpert, E. Schuhmann, U. Taubeneck 1971, Journal Allg. Mikrobiologie, 11, 19-33; J. Gumpert, U. Taubeneck 1983, Experientia Suppl. Vol. 46, 227-241) ,

L-form bacterial strains are principally suitable for the production of recombinant proteins for a variety of reasons. For example, their membrane, which is an adequate milieu for the production of membrane proteins, is freely accessible from the outside (K. Gura, J. Gumpert, C. Hoischen, 1997, IMB Anual Report 1996, 101-104; C. Hoischen, K. Gura, C. Luge, J. Gumpert 1997, Journal Bacteriol. 197, 3430-3436). Furthermore, protoplast-type L-form strains have no cell organelles apart from the cytoplasmic membrane, from which the protein produced has to be separated.

DD 269 166 AI describes the use of cell-wall-free Gram-negative bacteria, such as Pseudomonas, Agrobacterium, Proteus and Escherichia, as well as Gram-positive bacteria, such as Staphylococcus, Streptococcus, Bacillus _f Lactobacillus _r Streptomyces and Thermoactinomyces, to obtain recombinant gene products, such as Streptomyinase human, Interferon-alpha-1 or Prochy osin.

The DD 280 333 AI discloses a process for the production of milk-producing enzymes using stable L-form strains of bacterial or fungal origin.

DD 281 816 A5 relates to the production of serotype C streptokinase using L-form strains of e.g. P. mirabilis and Bac. subtilis.

So far, the production of more than 20 different proteins using L-form expression systems has been described. The proteins with L-shape cells were partly produced under semi-technical conditions in 2 to 100 1 fermenters (J. Gumpert and C. Hoischen 1998, Current Opinion in Biotechnology, 9, 506-509).

Gumpert and Taubeneck disclose L-form strains that are able to grow in culture media without the addition of serum or osmotic stabilizers (J. Gumpert and U. Taubeneck 1983, Experientia Suppl. Vol. 46 (1983) 227-241) ,

The known L-shape cells are sensitive because of their missing cell wall, for example, to environmental influences and chemical and physical changes in the growth medium. They are therefore more suitable for the production of proteins in small quantities, less for fermentations on an industrial scale (J. Gumpert and C. Hoischen 1998, Current Opinion in Biotechnology, 9, 506-509).

The production of recombinant gene products in membrane-bound form, whereby the functionally active molecules on the outside of the cell surface are freely accessible (surface display), is of great importance for the study of structure-function relationships, for interaction studies as well as for diagnostic and immunoprotective applications Importance. Here, antigenic determinants, single chain antibody fragments, heterologous enzymes, polyhistidyl tags and peptide libraries are expressed on the bacterial surface (Stähl, S. and Uhlen, M., TIBTECH 1997, 15, 185-192). The previously common bacterial cell types that are used for the surface display are Gram-negative E. coli strains and Gram-positive strains, e.g. Bac. subtilis and Staphylococcus species.

On the surface display with Gram-negative strains, the protein presented is usually fused with protein components of the outer membrane, such as OmpA, La B and PhoE, flagella proteins (flagellin) or proteins of the fimbriae (FimA, FimH), and thereby in the outer Anchored membrane. The disadvantages of this system are that (i) the proteins presented must be transported through the inner membrane, periplasm and cell wall (mureinsacculus and outer membrane), (ii) that the size of the proteins presented is limited and (iü) that a number of medical applications are excluded by numerous immunoreactive components of the cell surface.

In Gram-positive bacteria, the presented protein is usually fused with a surface protein of the cell wall (e.g. Protein A, M6 protein) and thereby fixed in the cell wall. The presence of cell-specific antigen determinants and the frequent occurrence of extracellular proteases have a disadvantageous effect on the surface display with Gram-positive bacteria. The protein presented must also first be transported through the z toplasmatic membrane and the cell wall.

The invention has for its object to provide new L-form strains for the biotechnological production of gene products, which have increased stability to chemical, physical and mechanical loads and which are therefore particularly suitable for fermentations under technical conditions and in particular for the production of membrane proteins ,

Surprisingly, this object was achieved by a process for obtaining modified L-form bacterial strains, in which

a) an L-shaped bacterial strain adapted to a complex nutrient medium is cultivated alternately at different temperatures in the range from 20 to 40 ° C., and

b) the cells are fermented under increasing hydromechanical load.

Basically all L-form strains, in particular L-form strains, with growth rates are suitable as the starting strain for step (a)

1 8 μ> 0.1 h ^" to cell concentrations of 10 cells / ml. According to the invention, stable L-forms of bacteria are preferably used, in particular stable protoplast-type L-forms.

Strains that grow stably can be found both in meat extract-containing complex media, preferably LFS medium, and in meat extract-free complex media, preferably those based on the complex nutrient components defined above, particularly preferably BHIB. be used. Meat extract-free media are preferred because they are more reproducible and less expensive to manufacture and to produce medical products.

L-forms suitable as starting strains are described, for example, by J. Gumpert and U. Taubeneck 1983, Experientia Suppl. Vol. 46, 227-241, described in the literature cited therein and in DD 269 166 AI. Preferred starting strains are the L-form strains of Escherichia coli, Proteuε mirabilis and Bacillus subtilis mentioned there. Further preferred L-form strains are those of Bacillus licheniformis _for Nocardia asteroides, Pseudomonas stutzeri, Staphylococcus aureus, Streptococcus faecalis, Streptomyces hygroscopicus and Thermo actinomyces vulgaris. Particularly preferred starting strains are the L forms of P. mirabilis LVI, P. mirabilis L99, E. coli LWF +, E. coli LWF- and Bac. subtilis 1.1 70.

The preferred L-form strains of P. mirabilis LVI, P. mirabilis L99, E. coli LWF +, E. coli LWF- and Bac. subtilis L170 are deposited in the DMSZ (German Collection of Microorganisms and Cell Cultures, Marscheroder Weg lb, 38124 Braunschweig). The deposit numbers are: DSM 7988 (Proteus mirabilis LVI), DSM 7990 (Proteus mirabilis L99), DSM 7989 {Escherichia coli LWF +), DSM 8012 {Escherichia coli LWF-) and DSM 7978 (Bacillus subtilis L170). It has been found that L-form bacterial strains which have been treated according to process steps (a) or (b) above, preferably (a) and (b), in addition to stable growth behavior, in particular due to a high mechanical strength and a high temperature tolerance distinguished. They are significantly more resistant to fluctuations in growth temperature, medium composition, pH and other fermentation parameters and are therefore particularly suitable for the production of recombinant gene products under technical conditions.

Steps (a) and (b) can be carried out simultaneously or in succession. The sequence is preferably step (a) followed by step (b). Step (a), step (b) or preferably both steps can be repeated one or more times.

Step (a) comprises a multi-stage growth regime with alternating growth temperatures. Step (a) is preferably carried out by varying the temperature alternately between two temperatures T1 and T2, T1 remaining the same during step (a) and T2 being varied. Here, the values for T2 are preferably below the value for T1. According to a preferred embodiment, T2 is gradually lowered and, after reaching the desired minimum temperature, is increased to a value above T1.

In step (a), the culture in question is first inoculated into fresh medium and incubated in a shaking incubator at a constant temperature (Tl) for 24 to 36 hours as a submerged shaking culture (stage 1). The cultivation takes place, for example, in 100 ml vessels, preferably in 35 ml of 3% BHI medium with the addition of 0.5% yeast extract. The cultivation is continued until a cell concentration of 10 cells / ml is reached.

Part of the culture from stage 1 is then transferred to fresh medium (inoculum about 10% v / v) and at a temperature incubated (T2), which is preferably lower than the temperature T1, over a period of preferably 18 to 48 hours, particularly preferably 24 to 36 hours (stage 2). Following stage 2, the culture is transferred back to fresh medium and cultivated at temperature T1 (stage 3). Tl is preferably the optimal growth temperature for the starting strain, for example 37 ° C., and is not changed in the course of step (a), while T2 is gradually reduced, preferably to a value of 20 to 22 ° C., particularly preferably about 20 ° C. T2 is preferably lowered to the desired target temperature in 5 to 10 stages, preferably about 7 stages, so that step (a) preferably comprises a total of 10 to 20 and particularly preferably about 14 stages. In each stage, the cells are preferably cultivated for 18 to 48 hours, particularly preferably 24 to 36 hours, at the respective temperature. The cultivation is preferably continued until a cell concentration of 10 cells / ml is reached.

The temperature T2 is preferably reduced by 2 to 5 ° C. per stage, the temperature change from stage to stage also being different. The use of more than two different temperatures, for example 3 or 4 temperatures, is possible. After the desired minimum temperature has been reached, according to a preferred embodiment, T2 can be raised to a value above Tl, preferably 2 to 5 ° C. above the optimal growth temperature, for example 40 ° C.

According to a particularly preferred embodiment, the culture is transferred every 24 hours in fresh medium of the same composition wherein the growth temperature alternately according to the following scheme is varied: Start: Tl = 37 ° C - T2 = 32 ° C → Tl = 37 ° C ^■ * T2 = 30 ° C → Tl = 37 ° C → T2 = 28 ° C - Tl = 37 ° C - T2 = 26 ° C - Tl = 37 ° C - T2 = 24 ° C - Tl = 37 ° C -> T2 = 22 ° C → Tl = 37 ° C - T2 = 20 ° C - Tl = 37 ° C - T2 = 40 ° C - T2 = 20 ° C end. As a result, strains are obtained which are more reproducible in the course of growth compared to the starting strains, more tolerant towards growth temperatures and more constant in the growth rate.

In method step (b), the L-shape cells are alternately exposed to increasing hydromechanical loads. For this purpose, the L-form cultures obtained in step (a) are fermented as a starting strain with varying shear forces and preferably also with varying aeration rates. Varying shear forces can be generated, for example, by varying the stirrer speed at which the fermentation medium is stirred.

Step (b) is preferably carried out in a fermenter with a net volume of 2 l, a height of 35 cm and a diameter of 18 cm, which is equipped with a wave disc stirrer with a diameter of 7 cm.

The fermentation regime is designed, for example, so that several fermenter runs are carried out in succession, the cells of one fermenter run being used as an inoculum for the next fermentation run.

1000 to 2000 ml of BHIB medium with 0.7% yeast extract and 1% sucrose with 10% (V / V) of the culture from step (a) or the previous fermenter culture are preferably inoculated and at a constant stirring speed (fixed speed VF) and aeration rate preferably fermented at 32 ° C to 37 ° C. The fermentation is continued up to a cell concentration of 10 8 to 109 cells / ml (about 24 to 48 hours). Under these conditions, the oxygen consumption of the L-shape cells is greatly increased. A decrease in the oxygen partial pressure p0 ₂ to values below approximately 5% should be avoided. For this purpose, the stirring speed is briefly increased to a fixed value (changeover speed VU) when an oxygen partial pressure of about 5% is reached and from 20 to 30 when a partial pressure is reached % reset to the fixed speed VF. The percentage refers to the saturation concentration of oxygen in the culture medium in question. In the course of step (b), the fixed speed VF and the changeover speed VU of the stirrer are changed in the successive fermenter runs. Step (b) preferably comprises 5 to 10, particularly preferably about 7, fermenter runs.

According to a particularly preferred embodiment, the stirring speeds in step (b) are changed according to the following scheme:

1st run: VF = 200 rpm - VU = 500 rpm;

2nd run: VF = 250 rpm - VU = 500 rpm;

3rd run: VF = 300 rpm - VU = 600 rpm;

4th run: VF = 350 rpm - VU = 600 rpm;

5th run: VF = 400 rpm - VU = 700 rpm;

6th run: VF = 450 rpm - VU = 700 rpm;

7th run: VF = 500 rpm - VU = 800 rpm.

The aeration rate is preferably set to 0.2 to 1.0, particularly preferably 0.6 to 1.0 volume units of air per volume unit of medium per minute (1/1 min), very particularly preferably about 0.7 1/1 min.

The exact composition of the nutrient media to be used in process steps (a) and (b) is selected according to the metabolic types and physiological characteristics of the parent bacteria. Media suitable for the respective parent strains are known, see, for example, J. Gumpert 1982, Zschr. Allg. Microbiol., 22, 617-627. Preferably, steps (a) and (b) use brain-heart-infusion-broth (BHIB), Todd-Hewitt-broth (THEB), tryptic-soy-broth (TSOYB) or L-broth (LB) as the medium , A medium of the following composition is particularly suitable for the starting strains preferred according to the invention: BHIB (Difco) 3 g, yeast extract (Difco) 0.5 g, sucrose 1 g, distilled Water 100 ml. Based on the known media, the optimal medium composition for strains such as streptococci and streptomycetes can be determined by routine test series.

When using the preferred L-form parent strain, the modified strains P. mirabilis LVIWEI, P. mirabilis L99WEI, E. coli LWF + WEI, E. coli LWF-WEI and B. preserved subtilis L170WEI. These were obtained from the German Collection of Microorganisms and Cell Cultures in Braunschweig under the accession numbers DSM 13363 (P. mirabilis LVIWEI), DSM 13364 (P. mirabilis L99WEI), DSM 13362 {E. coli LWF + WEI) and DSM 13361 {B. subtilis L170WEI).

The L-form strains obtained by the process according to the invention have the following advantages compared to the starting strains in addition to the ones already mentioned: immediate usability in fermentations, more homogeneous cell populations with a lower proportion of lysing cells, more stable metabolism, higher cell numbers, higher biomass concentrations, higher doubling rates in the exponential growth phase, more favorable pH profiles, better tolerance of anti-foaming agents, better tolerance of higher stirring speeds. The cells can be fermented in the temperature range from 20 to 40 ° C. directly at the temperature suitable for obtaining the desired gene product.

Another advantage of the modified L-form strains is that they show improved growth in process-relevant nutrient media such as BHIB, THEB, TSOYB, possibly with the addition of yeast extract (0.5-1%).

For P. mirabilis LVI WEI, for example, the following values were achieved compared to the parent strain: Parameters starting strain modified strain maximum cell count 1 x 10 8 x 10 ¹⁰ cells / ml maximum doubling 0.8-1.2 0.5 to 0.7 hours maximum achievable 3-4 5 to 8 g / 1 biomass concentration maximum tolerated 500 -600 600 - 800 rpm stirring speed

Temperature range for 28-38 20 - 40 ° C stable growth

Similar improvements have been found for the remaining L-form strains.

The L-form strains obtained by the process according to the invention are therefore particularly suitable for fermentations in stirred and airlift fermenters of 2 to 300 l and, due to their good suspendability, their ability to tolerate antifoams and hydromechanical stress factors, are advantageous in terms of process technology.

In comparison to the cytoplasmic membranes of the starting L-form strains, the cytoplasmic membranes of the L-form strains obtained according to the invention show characteristic differences in the protein pattern. They are described by way of example for E. coli LWF + and E. coli LWF + WEI in the exemplary embodiments and indicate genotypic and phenotypic changes.

Further genotypic changes in the new strains manifest themselves in differences in the band patterns of the chromosomal DNA after digestion with restrictases and separation by means of pulse field gel electrophoresis. For E. coli LWF + and E. coli LWF + WEI they are also documented in the exemplary embodiments. The L-form strains of, for example, E. coli, P. mirabilis and B. subtilis have no extracellular or periplasmic protease activities, and this significantly reduces the risk of proteolytic degradation processes on recombinant proteins.

In addition, the strains modified according to the invention, for. B. by adding 0.1-lμg / ml lyso-lecithin to the culture medium to stimulate the formation of extracellular membrane vesicles. This property is advantageous for the synthesis of recombinant membrane proteins.

Another advantage is that with the gene constructs (promoters, control sequences, origin regions, signal sequences) optimized for E. coli (parent form), well controllable gene expression and product synthesis is possible, so that heterologous means for a large repertoire of known means for genetic transformation and overexpression Gene products can be used. These gene constructs can be used for modified L forms of E. coli as well as for other strains such as P. mirabilis and Bac. can be used subtilis.

The L-form strains obtained according to the invention also have a more uniform cell morphology, a stable cell metabolism and stable, reproducible growth properties. They can be provided inexpensively in large quantities by fermentation in 1 to 300 1 fermenters.

Alternatively, new L-form strains adapted to technical growth conditions can be produced by targeted genetic manipulation of the starting L-form strains. For example, by mutations in the genes recA, hsdRl S f relA, supE and by the introduction of amber and ocher mutants, recombination, modification and restriction can be designed in such a way that improved transformation and plasmid stability are achieved. Furthermore, by inserting genes of the transcription and Translation control, such as JacJ and IacUV-T7, into the chromosome can improve expression and product synthesis.

The L-form strains obtained according to the invention are suitable for the production of any gene products, in particular for the production of recombinant proteins, preferably soluble, extracellular proteins and particularly for the production of membrane-bound proteins. The proteins can be used as biochemicals for molecular biological and medical research, as diagnostics, as drugs and as enzymes with potential for substance conversion.

For this purpose, the cells are first transformed in a manner known per se with a nucleotide sequence coding for a gene product, e.g. with a suitable vector containing the product gene under the control of one or more promoters. The vector preferably also contains a gene sequence which codes for a signal peptide which enables active transport of the gene product through the cytoplasmic membrane into the culture medium or anchoring of the gene product on the membrane (membrane anchor). The transformed strain is cultivated under suitable conditions, then, if necessary, the expression of the recombinant proteins is induced, e.g. by adding an inductor, and then isolating the recorabinant protein. Methods of obtaining gene products are also the subject of the present invention.

The cells are able to carry out post-translational modification processes. The lipid content of the L-form membrane is changed in such a way that it offers sufficient space for the insertion and enrichment of foreign membrane proteins and that the folding and processing processes essential for functionality can take place in or on the membrane.

The construction of suitable vectors is known per se. For this, the usual genetic engineering methods (T. Maniatis, E. Firtsch, and J. Sambrook 1989 Molecular Cloning: A Laboratory Manual, Cold Spring Harbor Lab. Cold Spring Harbor NY; FN Ansubel 1998, Current Protocols in Molecular Biology, Wiley and Sons) integrated the structural gene of a soluble or membrane-bound protein or fusion protein to be expressed into a plasmid suitable for expression. The promoters for the product genes, even if their overexpression is lethal, must be easy to regulate and thus enable subcloning. Promoters are preferred whose expression starts by adding an inductively acting substrate or substrate analog (inductor) or by a corresponding substrate shift, e.g. B. Iac-P / 0 and its derivatives such as lacUV, tac etc. (HA de Boer, LJ Comstock, M. Vasser, 1983, Proc. Natl. Acad. Sci. USA 80, 21-25), induction by IPGT- Additive (isopropyl-ß-D-thiogalactoside) or glucose / lactose shift; or fcetA-P / 0 (A. Skerra, 1994, Gene 151, 131-135); Induction by adding aTC (anhydro-tetracycline); Promoters whose expression start is initiated by changing the physiological conditions, e.g. B. λP _L (E. Remaut, P. Stanssans, W. Fiers 1981, Gene 15, 81-93); Start of expression by inactivation of repressor molecule cl ^ts after temperature increase); cspA-P / 0 (JA Vanisa, F. Baneyx, 1996, Appl. Environ. Microbiol. 62, 1444-1447); Start of expression by lowering the temperature); Vhb "oxygen-regulated element" (C. Koshla, J. Curtis, P. Bydalek, JR Swartz, JE Bailey, 1990, Biotechnol. Bioeng. 48, 151-160); Start of expression by lowering oxygen, p0 ₂ <5% saturation; inducible promoter hybrids consisting of DNA sequences from different promoters, e.g. B. P _L tetO-1 from tetA-P / 0 and P _L -P / 0 from phage λ (R. Lutz, H. Bujard, 1997, Nucl. Acid. Res. 25, 1203-1210); constitutive promoters and promoter hybrids which allow permanent gene expression without induction (e.g. P-Jacl (lac repressor gene), P-bla (β-lactamase gene), P-iacI / P-Jbia hybrid, speA (Streptococcus exotoxin A gene).

Furthermore, specific DNA sequences must be between the P / O region and the start codon of protein synthesis as ribosomal Binding site (rbs; also ≤'Λϊ.ne-.Delga.nσ sequence, SD) are inserted, which allow binding of the mRNA to the riboso as a prerequisite for the start of protein synthesis.

The expression cassette (P / O, SD, signal sequence, structural gene) can be flanked by transcription terminator structures in order to minimize possible interference with neighboring expression cassettes. Furthermore, the regulator genes required for effective control of the P / O regions (e.g. lad or 2acl for IacP / 0 and fcacP / O; tetR for tetAP / O; cl ^ts857 for P _L etc.) can be on the same or other autonomously replicating vectors localized or integrated into the chromosome.

Gene sequences coding for signal peptides are inserted N-terminally in front of the product gene. As signal peptides for gene products that are to be secreted into the culture medium, such as fusion proteins or certain protein domains, e.g. the extra-membrane regions of receptors, prokaryotic or eukaryotic signal peptides are suitable. The signal peptides of the OmpA protein (σinpA), the staphylokinase (sak), the alkaline phosphatase from E. coli (phoA), the streptokinase (speA) and the periplasmic pectin lyase from Erwinia (pelB) (AM Bushueva, AB Shevelev, J Gumpert, GG Chestukina, C. Hoischen, MV Matz, MV Kuryatova and VH Stepanov, 1998, FEMS Letters 159, 145-150; M. Kujau, C. Hoischen, D. Riesenberg and J. Gumpert, 1998, Appl. Microbiol Biotechnol. 49, 51-58; CH. Klessen, KH Schmidt, J. Gumpert, HH Grosse and H. Malke, 1989, Appl. Environm. Microbiol. 55, 1009-1015). However, some of the product genes already contain natural signal sequences that ensure transport across the membrane.

Signal peptides that cannot be split off by L-form signal peptidases are particularly suitable for anchoring proteins. These can be obtained from conventional signal peptides, for example, by the interfaces for signal peptidases, for example, by the Exchange of amino acids are modified so that they are not recognized by the signal peptidases.

For better detection and purification of the gene product, sequences coding for the structural gene for corresponding peptides (e.g. c-myc, His-tag, Strep-tag) or proteins (e.g. GST) with and without sequences in between for a specific peptidase cleavage can be added.

In the further course of the vector construction, these expression cassettes (promoter-signal sequence-product gene constructs) are integrated into a suitable plasmid. This must contain a suitable origin of replication and at least one selection gene for propagation in the L-form cells. For the L forms from Gram-negative bacteria, in particular for P. mirabilis and E. coli, the ColEl replicon (high copy number), the pBR322 replicon (= ColEl + rop gene, medium copy number) and the pI5A and pSCIOl are preferably suitable Replicons (low number of copies). For L-forms of Gram-positive bacteria like Bac. Subtilis are suitable for origins of replication of vectors with a broad host spectrum (e.g. pUBlOl from staphylococci, pIP501, pAMßl, pSM19035 from streptococci) or for streptomyces L-forms the replicons of the vectors pIYlOl, pWOR and pSG5. The choice of the origin of replication additionally allows a variation of the expression level of the structural gene over the number of copies and thus the gene dose.

The use of compatible replication origins and different selection genes on different vectors enables the use of dual or multiple vector systems in L-shape cells for the coexpression of different structural genes (S. Sieben, R. Hertle, J. Gumpert and V. Braun 1998, Arch. Microbiol. 170, 236-242).

Resistance to ß-lactam antibiotics (eg ampicillin) and chloramphenicol for all L- Forms unsuitable. Resistance genes suitable for the plasmid constructs must therefore be determined, preferably those against kanamycin, erythromycin, nourseothricin, phleomycin and neomycin.

The L-form strains are transformed with the expression vector using a standard method known per se (J. Gumpert, H. Cron, R. Plapp, H. Niersbach and C. Hoischen 1996, J. Basic Mircobiol. 36, 88-98 ). Then L-form cells are incubated with plasmid DNA and polyethylene glycol MG 6000 in an ice bath and at 37 ° C. After addition of LFS medium, incubation is carried out at 37 ° C. for 1-3 hours, and then this culture is plated on selective agar medium.

Kanamycin, erythromycin, nourseothricin and neomycin are preferably used as selective antibiotics according to the vector constructions. The positive transformants are propagated on agar medium and adapted to growth in liquid nutrient media by transferring them to fresh medium 2-5 times. Preferred growth media are LFS medium and BHIB medium with additions of 0.3-1% yeast extract, 1-2% sucrose and 2-50 μg / l selective antibiotic. The agar cultures or submerged cultures are checked for the presence of the intact plasmid DNA using restriction analysis and agarose gel electrophoresis.

A second transformation method is carried out in such a way that the transformation mixture (plasmid DNA / L-form cells / PEG) is filled with LFS medium 1: 1 after stays in the ice bath and at 37 ° C. and for 2 - 6 hours at 37 ° C is incubated. Then add 2 - 10 ml LFS medium with 2 - 50 μg / ml of the corresponding selective antibiotic and further incubate under shaking conditions at 30 - 37 ° C for 10 - 48 hours. With this method, mixed populations of transformants are obtained, from which single colony cultures can be grown by plating on selective medium. In the case of the use of dual vector systems (for example the coupled expression of structural genes with the addition of rifampicin under the control of the T7 RNA polymerase / T7 promoter system on the plasmids pGPl-2 and pSAT14), the L -Form cells first transformed with a plasmid and selected. The second plasmid is then transformed into these transformants, selecting for the presence of the selection markers of both plasmids. As a result, L-form transformant cultures are provided which contain one or more expression vectors.

For maximum product synthesis, the growth and fermentation conditions for the individual proteins can be different. They depend on whether the product synthesis is growth-linked or predominantly in the stationary growth phase, whether the product is formed more efficiently at temperatures from 26 to 30 ° C or 37 ° C, and whether the protein product is pH-sensitive and, e.g. like prochymosin, is degraded autocatalytically at pH values above pH 7.3. It has been found that the cells modified according to the invention are able to adapt quickly and without problems to the optimal growth conditions for the respective protein.

The overexpression of foreign proteins in the L-form cells can be controlled in such a way that no recombinant protein is formed in the course of the isolation and cultivation of the transformants and their growth in liquid media. Protein synthesis is only induced when high cell numbers are reached.

The essence of the cultivation is that the culture achieves the highest possible cell numbers (10 9-1010 cells / ml), that these are stimulated for expression and overproduction at the right time, that the proteins are secreted in high concentrations or built into the membrane, or are presented on the membrane that degradation of the proteins is avoided and that the culture supernatants or the L-shape cells with a maximum content of Protein products are provided for subsequent isolation.

The specific conditions and parameters are different for the producer strains used (L forms of E. coli, P. mirabilis, B. subtilis) and for the protein products and must be determined and optimized in each individual case. Specifically, this affects the composition of the nutrient media (especially C and N sources), the concentration of the selective antibiotics (0.5-50 μg / ml), optimal growth and synthesis temperatures (20-40 ° C, preferably 26-37 ° C), regulation of the pH value (pH 6.0-8.5, preferably pH 7.5), optimal oxygen input through selection of the fermentation tank, shaking frequencies (50-330 rpm), stirring speeds (200-600 rpm) ), Aeration rates (constant p0 ₂ ), feeding of C and N sources (especially glucose), time to induce gene expression (e.g. by adding IPTG, anhydro-tetracycline, 20-60 min temperature increase to 42 ° C ) and the length of the synthesis time (4-50 hours). The growth and product synthesis can be optimized at this stage by additional factors, e.g. B. low molecular weight effectors, vitamins, amino acid mixtures, lipid components, thiol reagents and non-metabolizable sugars.

An improvement in the formation of functionally active gene products can also be achieved by adding sugars, for example 1-5% sucrose. Such sugars are believed to improve the folding processes of various proteins.

Given the high structural and segregative stability of the plasmids in the L-form cells (e.g. of pHCl, pSIS2sak, pMK7GFP), growth and product synthesis can also take place without the addition of selective antibiotics (kanamycin, neomycin, nourseothricin, etc.).

The subsequent isolation and purification of the gene products depends on whether the protein is soluble or extracellular is obtained as a membrane-bound protein, for example peripheral or integral membrane protein. Since, in contrast to all other producer cells, the L-shape cells generally have no other cell organelles such as flagella, fimbriae, spores, cell walls and internal membrane systems apart from the cytoplasmic membrane, the cleaning steps required to separate these components are eliminated. The membranes and membrane proteins can be isolated and purified relatively easily by cells (osmotic shock, ultrasound, French press) and subsequent centrifugation and washing in buffer solutions.

If extracellular soluble proteins are obtained, the L-shape cells are separated from the nutrient medium by centrifugation (6000 g / 10 min) and from this supernatant using the known methods of protein isolation (precipitation, sedimentation, extraction, filtration, electrophoretic separation; Affini - activity, ion exchange, size exclusion and hydrophobic chromatography, etc.) the proteins are separated and purified.

To isolate membrane-bound proteins, the L-shape cells are sedimented and washed in the same way by centrifugation. The protein-membrane complexes are obtained by lysing the cells (osmotic lysis, ultrasound treatment, freezing and thawing, French press treatment). The membranes (empty cells) are then washed in magnesium-containing (eg 0.1% MgSO ₄ ) buffer solutions.

The membrane-bound proteins are detected using known methods, preferably by immunochemical methods based on synthetic peptides (Western blot, dot blot, ELISA, synthetic sequence-specific antibodies), cytochemical methods (immunoelectron microscopy with immunogold, fluorescence microscopy), radiochemical methods (Labeling with S methionine or H-leucine) and functional tests (enzymatic

Reactions, binding kinetics) Further isolation and enrichment depend on the intended use, ie whether the protein product is to be obtained as a pure protein or as a complex with membranes or lipid components. The protein membrane complexes are usually in the form of vesicles (0.01-5 μm diameter) and can be obtained as a suspension in buffer solutions (TRIS, BBS, with additions of 0.1% MgS0 ₄ , phenylmethylsulfonfluoride, dithiothreitol) or be kept.

The membrane vesicles can be converted into inside-out vesicles by inversion using French press treatment or freeze-thaw. The inner areas of the protein molecules on the cytoplasm side are freely accessible on the outer surface of the membrane vesicles. Inverted protein membrane complexes produced in this way make interaction studies and structural elucidation of the cytoplasmic extramembrane domains possible.

In a further variant of the method, the lipid matrix of the membranes can be dissolved using suitable detergents (SDS, plantars, Tween 20, Triton X 100). The integral and peripheral membrane proteins are released, and these can be isolated and purified as soluble or aggregated protein molecules.

In an alternative step of the method, the membrane-bound proteins isolated in this way can be reconstituted in lipid structures with a defined molecular composition. In this way, their correct molecular configuration and functionality can be maintained or restored. Many membrane proteins are only functionally active if they are embedded in a suitable lipid environment. Particularly suitable lipids are phospholipids with a pronounced tendency to form unilamellar bilayer vesicles (for example phosphatidylethanolamine, phosphatidylglycerol, phosphatidylcholine). The L-form strains according to the invention and the method according to the invention for the production of gene products are particularly suitable for the production of membrane-bound proteins. Membrane-bound proteins are understood to mean those proteins which are bound to biomembranes. This includes both the so-called membrane proteins, which bind to membranes due to their chemical and physical properties, either integral or peripheral, as well as proteins that do not themselves bind to membranes and are only bound to the membrane by suitable membrane anchors.

The term membrane protein includes integral or peripheral membrane proteins, such as receptors (e.g. acetylcholine, bradykinin, endothelin, hormones), carrier proteins (e.g. for amino acids, sugars, ions, peptides, compatible solutes, electron transport), ion channels, ABC transporters, preprotein translocators.

The method according to the invention and the L-form strains according to the invention are particularly suitable for expression and for the production of bacterial "outer membrane proteins" (Omps), in particular Omps with a β-sheet structure. These proteins are located in the outer membrane of Gram-negative cells. Surprisingly, it was possible for the first time to express Omps in large quantities even in soluble form. Omps are difficult to produce in pure form using conventional bacterial expression systems (Meens et al. 1997, Applied. Environment. Microbiol. 63: 2814-2820). The use of L-shaped strains for the production of omps, in particular omps in soluble form and omps with a β-sheet structure, has not previously been described and is also an object of the invention.

Outer-membrane-proteins (Omps) Gram-negative bacteria, especially pathogenic species, are suitable in soluble or membrane-bound form for interaction tests, structure-function studies, diagnostics and vaccination. The second group of membrane-bound proteins includes, for example, soluble proteins and hydrophilic proteins, which are only able to bind to lipid membranes after being linked to, for example, a hydrophobic amino acid sequence. The hydrophobic amino acid sequence serves as a membrane anchor.

Preferred membrane anchors are homologous and heterologous signal peptides, such as the eukaryotic signal peptide of the SERP protein from Plasmodium falciparum, which have interfaces which are not recognized by the bacterial leader peptidases.

Further preferred membrane anchors are sequences of homologous and heterologous transmembrane regions of membrane proteins, such as hydrophobic transmembrane helices of homologous and heterologous prokaryotic and eukaryotic membrane proteins, preferably helix 1 or helices 1 to 3 of the lactose permease LacY from E. coli, the preprotein translocase SecY from E. coli or the swarm protein CcmA from P. mirabilis.

Synthetic hydrophobic amino acid sequences with 8 to 150, preferably 10 to 120, very particularly preferably 10 to 30 amino acids, such as the leucine zipper, are also suitable. Amino acid sequences are considered to be sufficiently hydrophobic if they bind to biomembranes according to the methods published by G. von Heijne (by Heijne G., "Assembly of Integral Membrane Proteins" in Biological Membranes: Structure, Biogenesis and Dynamics, Springer Verlag Berlin 1994, JAF Op den Kamp (Editor), pages 199 to 205; Cserzo, M., Wallin, E., Simon, I., Von Heijne G., Eloffson, A. Protein Eng. 1997, 10: 673-676 Membrane anchors are described in the exemplary embodiments.

The anchoring of proteins to membranes enables the surface presentation of the proteins on the L-shape membranes. Due to the lack of cell wall components (peptidoglyc n, outer membrane, lipopolysaccharides) and extracellular With the L-form strains, it is possible to present the proteins of interest directly on the cytoplasmic membrane. The lack of antigenic components is advantageous in terms of medical applications such as vaccinations and diagnostic methods. This opens up considerable advantages over conventional gram-positive and gram-negative bacterial surface display systems. In addition, high concentrations of the proteins can be achieved on the L-shape membrane (up to about 100 mg / 1). It has surprisingly been found that when proteins are anchored in the cytoplasmic membrane with heterologous and homologous anchor sequences, the proteins are largely arranged on the outside of the cytoplymatic membrane and are biologically active. The proteins are therefore easily accessible for interaction with extracellular components, functional tests and interaction studies. The anchoring also proved to be very stable, and the protein molecules were not torn from the membrane anchors during the fermentation, for example.

The surface presentation of proteins makes it possible, for example, to obtain novel vaccines and interaction screening systems. For this purpose, the desired antigen is anchored on the membrane of L-shape cells, and the cells are then used for vaccination. Only the active, i.e. antigenic components used, for example, by proteins for anchoring. Due to the high concentration of protein on the membrane, only a small number of cells is required for vaccination, and the use of patogenic cells or proteins can be avoided entirely.

In addition to various antigenic determinants of pathogenic organisms for vaccinations, the proteins that are particularly suitable for the surface display also include single chain antibodies and antibody fragments, heterologous enzymes, polyhistidyl tags and peptide libraries. The modified L-shape cells are suitable for use in diagnostics and Therapy and for the preparation of agents for diagnostics and therapy, as biocatalysts, and for use in interaction screening.

The use of L-form cells for the surface presentation of proteins has not been described to date and is therefore also a subject of the present invention, as are methods for the surface presentation of proteins using L-form cells and the use of L-forms with anchored to the cytoplasmic membrane Proteins for the manufacture of therapeutic and diagnostic agents. These methods include the steps described above for the production of proteins using L-forms, the cells being transformed with the gene construct from an anchor sequence and a protein sequence. When isolating the gene product, the cells are preferably not disrupted by surfactants or the like but rather isolated as a whole.

All L-Forms of bacteria are suitable for the surface presentation of proteins, in particular stable L-forms and very particularly stable protoplast-type L-forms. Preferred and particularly preferred L-forms are those mentioned above as starting strains for the production of modified L-forms, in particular the L-forms modified according to the invention.

The L-form strains according to the invention and the method according to the invention for producing gene products are also suitable:

for the production of proteins for use as pharmaceuticals and diagnostics, such as, for example, pharmaceutically active enzymes and enzyme activators (exo- and endopeptidases, staphylokinase, streptokinase, hemolysin activator ShlB), growth factors, peptide hormones, antibody constructs (for example Fab, Fv fragments, their single chain variants , Miniantibodies, diabodies, complete antibody proteins), membrane-bound fusion proteins and other recombinant fusion proteins, with mono-, bi- or multivalent binding properties for medical diagnostics or therapy (eg of tumors), including receptors with ligand binding properties;

for the production and presentation of immunodeterminants such as surface antigens of pro- and eukaryotic organisms (e.g. the SERP and MSPl protein of the malaria pathogen Plasmodium falciparum, viral coat proteins (e.g. from the HIV virus and other retroviruses), viral transcriptases for antibody formation and immunization;

for the production of enzyme activators and enzyme inhibitors such as e.g. Protease inhibitors;

for the production of enzymes and proteins for signal transmission;

and for the production of precursor proteins, i.e. Precursors of mature, biologically active proteins, which are retained due to the lack of extracellular proteolytic activity of the L-form cells and are used as an inactive form for therapeutic and diagnostic purposes and are only activated in the organism or diagnostic test.

The proteins obtained are functionally active and contain no disruptive membrane components, e.g. Lipopolysaccharides of the outer membrane of Gram-negative bacteria, which interfere with the production and functionality of the protein products. The gene products mentioned are either translocated into the culture medium or isolated in membrane-bound form.

The invention is explained in more detail below on the basis of exemplary embodiments. The examples were carried out using the deposited L-form strains, these being obtained from process steps (a) and (b) starting from the known strains. Example 1 shows that the modified strains are genotypically modified.

Example 2 shows that they have phenotypic and genotypic membrane changes.

In example 3 it is shown that strains modified according to the invention are better fermentable and form more product than the starting strain.

Example 4 describes the controlled gene expression and product synthesis with strains modified according to the invention.

Example 5 describes the anchoring of recombinant proteins in the cytoplasmic membrane using homologous and heterologous peptide sequences of integral membrane proteins as membrane anchors.

embodiments

Embodiment 1

Comparison of the chromosomal DNA (genotype) of the modified L-form strain Escherichia coli LWF + WEI with that of the parent strain Escherichia coli LWF +

Pulse field gel electrophoresis enables DNA fragments to be separated over a large length range on a gel. This allows a comparative analysis of the genomic DNA of species and strains.

Changes in DNA that have an impact on the recognition sequences of restriction enzymes result in changed band patterns. This enables statements about the genetic diversity of a strain to be made after restriction treatment (Lezhava, A., J. Bacteriol. 1995, 177, 6491-6498; Pandza, K, Microbiol 1997, 143, 1493-1501).

material and methods

The L-form strains E. coli LWF + WEI and E. coli LWF + and the cell wall-containing parent strain E. coli WF + are grown under the same conditions. The culture took place in steep breast bottles (100 ml) with 30 ml LFS medium and additions of horse serum (6% v / v), yeast extract (0.7%) and sucrose (4%) at 37 ° C on a rotary shaker at 200 U / minute After a 3-6 hour cultivation, samples are taken from each strain in an equivalent corresponding to an optical density of 2, measured at 550 nm, in order to obtain comparable final biomasses. After centrifugation of the cell suspension at 3000 × g, 4 ° C. and 10 min, the pellet was carefully cautiously placed in an osmotically buffered yeast EDTA-sucrose solution (HES buffer according to Evans, M., Dyson, P. 1993, Trends in Genetics, 9, 72-78) resuspended, mixed with almost solidified agarose (0.7%, BioRad) and then solidified at 4 ° C. As a result, unspecific band patterns as a result of shear effects can be avoided. The samples of the parent strain E. coli WF + were then treated with lysozyme (Serva Electrophoresis, 1 mg / ml HES, 2 hours at 37 ° C). The subsequent alkaline lysis of the cells within the agarose block (approx. 0.2 cm), combined with sufficient protein digestion (1 mg Proteinase K (Merck Eurolab) / ml N-lauroylsarcosinate-EDTA-glycine-NaOH solution (NDS solution; Evans , M., Dyson, P. 1993, Trends in Genetics 9.72-78) for 16 hours at 37 ° C), the necessary washing steps follow: 1 x 15 min with NDS, 1 x 15 min with yeast EDTA solution (HE buffer), 1 x 1.5 hours with HE buffer + 50 μg Pefabloc (Röche Diagnostics) / ml at 37 ° C, 5 x 30 min with HE. After such a treatment, the DNA was in a form that allows sequence-specific cutting with restrictases. A sufficient amount of 60 units of the respective restrictase was added to a piece of agarose (about 0.05 ₃ cm) and the incubation time of 16 hours was chosen to achieve complete cleavage. The separation conditions of the DNA fragments in a 1.5% gel (SeaKemGold, FMC Bioproducts) at 170 V, 22 hours, pulse times of 2, 5-38 s and 12 ° C are based on optimized empirical values. A pulse field gel electrophoresis apparatus of the type CHEF-DRII (BioRad) was used.

Results:

The restriction endonucleases used (Sdal from MBI Fermentas, all others from New England Biolabs) have the following different specific cleavage sequences:

Spei = A / CTAGT Xbal = T / CTAGA

Notl = GC / GGCCGC Swal = ATTT / AAAT

Avrll = C / CTAGG Ascl = GG / CGCGCC

Sfil = GGCCNNNN / NGGCC Sdal = CCTGCA / GG

The restriction endonucleases Xbal, Notl, Swal, Avrll, Ascl, Sfil and Sdal gave largely identical basic fragment patterns in both L-form strains and the parent strain. This is evidence that taxonomically it is the same organism, i. H. E. coli, acts (Fig. 1, 2).

Figure 1 shows cleavage patterns of chromosomal DNA of the modified L-form strain E coli LWF + WEI (2, 4, 6, 8) and the starting strain E. coli LWF + (3, 5, 7, 9) after digestion with 60 units each Restriction endonucleases Swal (2, 3), Spei (4, 5), XBal (6, 7) and Notl (8, 9) (all from New England Biolabs); lanes 1 and 10 show length markers, lane 1: low range (New England Biolabs), lane 10: lambda ladder (New England Biolabs).

Figure 2 shows the cleavage pattern of chromosomal DNA of the wall-containing parent strain E. coli WF + (2, 5, 8), the L-form Starting strain E. coli LWF + (3, 6, 9) and the further developed strain E. coli LWF + WEI (4, 7, 10) after digestion with 60 units of the restriction endonucleases Spei (2, 3, 4), Notl (5, 6, 7) and Xbal (8, 9, 10) (all from New England Biolabs), track 1: length marker low range (New England Biolabs).

After digestion with Spei, there is a clear difference between the bands in the size range between 240kb and 290kb in the E. coli LWF + WEI strain and in the E. coli LWF + strain. This reproducible difference is a clear indication that the further developed E. coli LWF + WEI strain is genotypically changed compared to the original E. coli LWF + strain (Fig.l., see arrows).

Splits with Spei, Notl and Xbal resulted in a pattern in the L-form strains, which is different in each case from that of the N-form (Fig.2., See crosses). Only Spei showed a different difference from the N-shape (Fig.2., See circles).

A comparison of the similarities and differences in the band patterns clearly shows that the strains E. coli WF +, E. coli LWF + and E. coli LWF + WEI belong taxonomically to the same species, that both L-form strains compared to the N-form parent strain show genotypic differences and that the further developed L-form strain E. coli LWF + WEI is genotypically changed compared to the collection strain E. coli LWF +.

Embodiment 2

Difference in the protein components in cytoplasmic membranes of the L-form strains Escherichia coli LWF + and E. coli LWF + WEI

In addition to the comparative analysis of the chromosomal DNA after restriction treatment, the comparative analysis of the protein patterns of two strains also allows conclusions to be drawn about genotypic and phenotypic changes. Using two-dimensional gel electrophoresis (2D-PAGE), a detailed separation and characterization of protein mixtures is possible. The first step is the separation according to the isoelectric point (pl) in a focusing gel (IEF). In the second step, the focused proteins are separated according to their molecular weight (MW) in an SDS-polyacrylamide gel (SDS-PAGE).

In the exemplary embodiment, the membrane proteins of the starting strain E. coli LWF + were compared with those of the strain E. coli LWF + WEI modified according to the invention. The restriction to the membrane proteins was chosen because the L-form membranes contain only about 500 different proteins, while a multiple of them is present in the whole cells. Furthermore, the membrane proteins are for the most part essential and usually always present in the membrane. Reproducible qualitative differences in the pattern of the membrane proteins are therefore an indication of structural and functional differences in the genome.

material and methods

Cultivation of the cells:

The cells of the two strains are grown under identical conditions (BHI medium with additions of 0.5% yeast extract and 5% v / v horse serum, incubation in a shaking incubator at 37 ° C.), centrifuged after 24 hours (6000 × g, 10 min ), washed in 0.4 M sucrose and lysed by osmotic shock (0.05 M TRIS / HCl powder pH 7.0 with the addition of 0.1% MgSO ₄ and 30 μg / ml DNAse). The membranes are isolated and cleaned by ultracentrifugation (80,000 xg, 20 min, 4 ° C, Beckmann Optima XL80) and washing in 0.05 M TRIS / HCl buffer with 0.1% MgSO _A. Sample treatment:

The cleaned membrane fractions are first washed with 5 times the amount of distilled water and then centrifuged for 45 min at 5 ° C at 14000 rpm (Sorvall centrifuge type RMC 14). The pellet is processed as described below.

Solubilization of the membrane proteins:

The washed membrane pellet is in 6 times the amount of solubilization buffer (9.5 M urea, 4% 3- [(3-cholamidopropyl) - dimethylammonio] -l-propanesulfonate (CHAPS, Serva), 5% of a 40% ampholyte solution 3-10, 100 mM dithiolthretitol (DTT) was added and additional solid urea was added in an amount of 45% of the membrane weight in order to bring the urea concentration of the total solution back to ~ 9.5 M. The suspension is dissolved by shaking at room temperature The mixture is then centrifuged for 50 minutes at 75,000 rpm in an ultracentrifuge (type Beckmann Opti a TLX at 20 ° C. The supernatant contains the membrane proteins dissolved under the selected conditions. 15-20 each μl of this solution are applied to the focusing gels and analyzed in two dimensions.

electrophoresis:

® The Investigator 2-D. Was used to analyze the protein components

Electrophoresis system used by Oxford Glyco-Systems.

Isoelectric focusing (1st dimension): no prefocusing, maximum current 110 μA / gel, constant voltage 1000 V (17th

Hours) and 2000 V (30 min), d. H. 18000 Vh in total.

SDS-PAGE (2nd dimension): 11.5% polyacrylamide gels (Duracryl

30.65% T), no stacking gel, maximum voltage 500 V, 20 W / gel. All gels are made with Coomassie Brilliant Blau G-250 using the method of Neuhoff et al. (Electrophoresis 1988, 9, 255-262), in which the colloidal properties of this dye are used.

Results

Figure 3 shows membrane proteins of Escherichia coli LWF + (Gel AI) and E. coli LWF + WEI (Gel Bl) after separation with 2D-PAGE in the pI range 4.8 - 6.7 and the MW range 31 - 60 kDa , The black arrows mark spots or spot patterns that are only present in the E. coli LWF + strain, and the white arrows document proteins that are specific for the E. coli LWF + WEI strain. The comparison of the spot patterns in the gel areas 3.5 <pl <7.0 and 22 kDa <MW <80 kDa showed approx. 150 detected proteins in the membranes of both L-form strains. The majority of the spots are identical. Of the twelve divergent proteins, six were only in the original E. coli LWF + strain and six were only in the E. coli LWF + WEI strain.

In Figure 3, the gel areas 4.8 <pl <6.7 and 31 kDa <MW <60 kDa are enlarged as sections, and they each show four different proteins. Due to the completely identical cultivation conditions and sample treatments and the repeatedly reproduced data, it must be concluded from the results that the composition of the membrane proteins in the E. coli LWF + WEI strain has changed significantly and that this is due to changes in the genotype. Embodiment 3

Comparison of growth and product formation of the recombinant L-form strains Proteus mirabilis LVIWEI and Proteus mirabilis LVI

The production of recombinant proteins that can be used for vaccination is an urgent task, especially for diseases that were not previously accessible, e.g. Malaria. The MSP1 gene encodes a protein that is synthesized by the merozoite stages of the Plasmodium falciparum pathogen and is a candidate for vaccination strategies against malaria. To obtain the protein, i.e. in the execution of the 42 kDa C-terminal fragment, the strains P. mirabilis LVI and P. mirabilis LVIWEI were transformed with the plasmid p6H-42-3D7. In the example, the fermentation of both transformants is compared and documented that the new P. mirabilis LVIWEI strain has better properties in terms of growth and product formation.

material and methods

The P. mirablis LVIWEI (p6H-42-3D7) and P. mirabilis LVI (p6H-42-3D7) strains contain the same plasmid with the gene for the 42 kDa fragment of the malaria surface protein 1 (MSP1) in the allele -Variant 3D7 (MAD20) of the human-specific pathogen Plasmodium falciparum (Pan, W. et al. 1999, Nucleic Acids Research 27, 1094-1103). The θΛ? PA signal peptide is fused to the 42 kDa fragment, which is necessary for secretion into the medium. The transformants were obtained according to the same steps as described in the patent description and in exemplary embodiment 5. They are tested for plasmid identity (restriction pattern) and the product formation which can be induced under the control of the PtetO-1 promoter (Lutz R. and Bujard, H.1997, Nucleic Acids Research 25, 1203-1210). For the fermentation, precultures from the growth were first transformants adapted in liquid media. A first preculture was carried out at 37 ° C. (100 ml glass flask with 35 ml BHI medium and additions of 50 mM Na phosphate pH 7.2 and 50 μg / ml kanamycin) for 24 hours as a shaking culture at 220 rpm second preculture cultivated on the same scale at 28 ° C. for 24 hours. This serves as an inoculum for the third preculture (500 ml glass bottles with 150 ml fermentation medium, cultivated for 12 hours at 26 ° C). After a microscopic inspection of the pre-cultures, the fermenters are inoculated.

The fermenter used (BIOSTAT B device, Braun BBI Melsungen) is equipped with a stirred tank culture vessel B2 (working volume 2 1), aeration device, stirrer shaft with two paddle stirrers B5 in the medium and a 6-blade disc stirrer B2 in the foam area, a pH probe ( Ingold 405D-K8S / 200), a p0 ₂ probe (Mettler Toledo 34 100 3057), a foam probe, a gas mixing station with 2 ml mass flow controller for air and oxygen and a supply air filter 0.2μm (Sartorius Midisart 2000), Exhaust air cooler with foam trap, sterile filter (Gelmann Acro 50ST), exhaust gas analysis system (Hartmann and Braun, Frankfurt) with Uras 10p for C0 ₂ analysis and Magnos 6G for 0 ₂ analysis, cooling water circuit cooler KK4s (Medingen, 6 ° C), dosing device for glucose with Peristaltic pump WM 101U / 2rpm (Watson-Marlow, silicone hose ID = 1.6 mm) and control via timer, off-line analysis for glucose with ECA 2000 glucose analyzer (Medingen).

The medium in the fermenter is 1.35 1 BHIB (35 g / 1) dissolved in Na phosphate buffer (50 mM, pH 7.2) with the addition of glucose (0.5%), sucrose (1%), yeast extract (0 , 1%), Na fumarate (40 mM), kanamycin (50 μg / ml) and ampicillin (200 μg / ml). It is inoculated with 150 ml of the 12-hour preculture to a starting cell concentration corresponding to an OD ₅₅₀ nm = 0.5.

The fermentation regime includes: temperature = 26 ° C; pH = constant pH 7.2 (+/- 0.3), regulated with H ₂ S0 (12%) and NaOH (12%); Ventilation rate = 20 SLPM constant; Stirring speed = 100 - 500 rpm, coupled to the specified pO ₂ concentration of 20%; Addition of inductor anhydro-tetracycline (400 μg / 1, after the first doubling of the OD and 400 μg / 1 after the second doubling of the OD, then 12 hours of continued fermentation). Ucolub was added as an anti-foaming agent as needed. At the measuring point times shown in Figs. 4a and 4b, samples are taken (10 ml) and the cell concentration as optical density (OD as extinction at 550 nm, photometer Spekol 11 Zeiss) is determined as a measure of the biomass.

After centrifugation (6000 x g, 10 min), the fermentation samples are fractionated into the supernatant with soluble product and into the sediment with cell-bound product. The product formation is determined by SDS gel electrophoresis and Western blot with product-specific antibodies and quantitative evaluation of the bands (scan and evaluation software Phoretix ID, NonLinear Dynamics Ltd, UK).

Results

The results of fermentation kinetics and product formation with Proteus mirabilis LVI (p6H-42-3D7) (a) and P. mirabilis LVIWEI (p6H-42-3D7) (b) are shown in Figure 4. The amounts of soluble and cell-bound malaria protein synthesized are given as relative units ("units" = area x color intensity of the scanned product bands in the Western blot).

1. Under largely the same conditions (preculture from intact L-shape cells, the same growth media, seeding densities, growth temperatures, pH control, glucose feeding, induction of gene expression and control of the oxygen input with threshold value of pO ₂ = 20% by coupling to increasing the stirring speed ) shows the transformant P. mirabilis LVIWEI (p6H-42-3D7) of the further developed strain clearly better properties.

2. In comparison to the P. mirabilis LVI strain (p6H-42-3D7), it shows faster growth immediately after the start of fermentation, a pronounced exponential growth phase up to 12 hours, much higher cell numbers and biomass values, combined with much higher C0 ₂ formation and thus more active metabolism, as well as better tolerance for anti-foaming agents. The transformant of the parent strain P. mirabilis LVI (p6H-42-3D7), on the other hand, shows a decrease in metabolic activity after the addition of antifoam, illustrated by the decrease in CO ₂ formation and in the consumption of 0 ₂ .

3. The transformant P. mirabilis LVIWEI (p6H-42-3D7) achieves a significantly higher volume yield of synthesized malaria protein. This affects both the amount of cell-bound protein product (Fig. 4a and 4b) and the amount of soluble product, which remains only small in both strains.

Example 4:

Functionality of different expression vectors with controllable expression performance in L-form cells from Proteus mirabilis LVIWEI

Controllable overexpression of the product genes is of crucial importance for the successful use of bacterial cells for the synthesis of recombinant protein products. Example 4 documents that such an inducible product synthesis based on the gene constructions and regulatory principles optimized for E. coli is also possible in L-form cells from P. mirabilis LVIWEI. A) Vector construction and proof of the controllable expression performance:

Methodology:

The vectors used were constructed using known genetic engineering methods (Maniatis et al., 1989, Molecular Cloning: A Laboratory Manual. Cold Spring Harbor Lab. Cold Spring Harbor NY; Ausubel, FN, 1998, Current Protocols in Molecular Biology. Wiley and Sons) ,

As a simple proof of the functionality of the vectors, the gene for the green fluorescent protein (GFP; Crameri et al., 1996, Nature Biotechnol. 14, 315-319), representative of the genes of a wide variety of recombinant proteins, was inserted into the expression cassettes under the Control of different promoters cloned. The correctly folded, functional GFP has a chromogenic center that emits greenish light (509nm) when excited in the UV range (395nm). The detection and the strength of the green fluorescence are a measure of the efficiency of the vectors and the product formation in L-form cells with regard to the induction of the transcription start (mRNA formation), the translation (protein synthesis according to the coding mRNA sequence) and the correct folding of the Protein.

For an inducible and easily regulatable protein formation, the GFP gene is under the control of the promoters lac-P / O (+ lacl repressor gene; repressor inactivation by adding 5mM IPTG) or tetA-P / O (+ tetR- Repressor gene, repressor inactivation by adding 200μg / ml anhydro-tetracycline [aTC]). For constitutive product formation, the GFP gene is under the control of the promoter region of the lacI repressor gene (P-iacI) or additionally under the control of the promoter region of the β-lactamase gene (P-jbla) as a tandem Hybrid (P-lacI / P-jbla). Vectors for the lac-P / O-controlled GFP are used as an example for the regulation of the expression level via the gene dose effect, ie influencing the synthesis of the recombinant protein by different numbers (copies) of the vector DNA with the coding gene per cell -Expression constructed using the replication origins ColEl, pBR322 and pl5A.

The vectors were transferred to the L-form strains as described in embodiment 5. All vectors carried the kanamycin resistance gene as a selection marker.

Results:

L-form cells from Proteus mirabilis LVIWEI with the corresponding vectors are cultivated in a shake culture (LFS medium with 0.5% yeast extract; 18 hours at 37 ° C.) without inducers. From these cultures and the plasmid-free control strain, 0.1 ml of cell suspension are spread onto LFS medium agar plates (without or with the addition of an inductor). After 24 hours of growth at 37 ° C, excitation with UV light to emit the green fluorescent light and photography with a CCD camera.

The P. mirabilis LVIWEI cells grown and induced on the agar plates in Figure 5 contain vectors with the following features (Table 1).

Table 1: Promoter-gene constructs for GFP synthesis in P. mirabilis LVIWEI

No. Vector RReepplliikkaattiiooππssoorriiggiinn KKooppii ieenn // ZCell expression control by induction

0

1 pMK310gfp pl5A 5 - 10 lacP / O (+ / fld repressor) + IPTG

2 pMK311gfp pBR322 30 - 70 tocP / O (+ Jαcl repressor) + IPTG

3 pMK31gfp ColEl (pUC) 120 - • 200 lacP / O (+ fad repressor) + IPTG

4 _P MK3c2gfp ColEl (pUC) 120 - ■ 200 P-tαcI / P-bla Ix constitutive

5 pMK3c-gfp ColEl (pUC) 120 - • 200 P-lacl consumed

6 pMK7gfp ColEl (pUC) 120 - • 200 tetP / O (+ tertR repressor) + aTC

The results summarized in Fig. 5 document that

Cells without GFP expression vectors (No. 0) show no fluorescence under all conditions,

- the three constructs with the lac-Ε / O (No. 1-3) only synthesize the GFP after induction with 1-10 mM IPTG,

- In this case, more GFP is formed with plasmids which are present in high copy number (No. 3-6, with ColEl / pUC ori) than with those which are only present in a few copies in the cells (No. 1, with pl5A ori ),

- A specific gene expression is also possible with the tetA-P / O (No. 6) and

- In the cells containing vectors with the GFP gene under the control of the constitutive iacI-P / O (No. 4), GFP synthesis takes place under all conditions tested.

These results allow the conclusion that the expression vectors constructed and optimized for the usual E. coii host strains also work effectively in the L-form cells of P. mirabilis LVIWEI. B) Segregative and structural stability of the expression vectors in L-form cells

Methodology:

P. mirabilis LVIWEI (pMK3c2GFP) with constitutive GFP expression (No. 4 in Tab. 1 and on agar plate in Fig. 5) shake cultures in LFS medium with and without selective antibiotic (50μg / ml kanamycin) as in Example 5 described, which are transferred to fresh medium after 24 hours, ie after approx. 4-5 cell generations, and again cultivated over a total of 12 passages. After every third passage, dilution series (10 ^" to 10 ^" ) of the cultures are carried out on LFS medium agar plates with and without selective antibiotic, and after 3 days of growth, the fluorescent or non-fluorescent individual colonies are counted under UV light (Fig 6).

Results:

The course of the proportion of fluorescent single colonies, i.e. the plasmid-containing cells in the cultures with and without selection pressure do not produce any significant differences even over a long cultivation period (with over 50 generations without a selective antibiotic). This is documented in Figure 6. The green fluorescence of all plasmid-containing individual colonies thus illustrates the structural and functional stability of the vectors.

C) Comparison of vector efficiency in L-shape and N-shape cells:

Methodology:

As an example of the productivity of the L-form expression system, GFP expression with various vectors in L-form P. mirabilis LVIWEI cells compared with expression in N-form cells from E. coli production strain RV308. Both cell types are cultivated under the same conditions in complex medium and GFP expression is induced. The cell concentration of the cultures (g dry biomass / 1) was determined by measuring the absorption at 550 nm. The cells are harvested by centrifugation, disrupted by ultrasound treatment, the GFP activity (fluorescence) quantified on the fluorescence photometer and the amount of the total GFP protein synthesized on the basis of the activity via denaturing SDS-PAGE, Coomassie staining and gel evaluation and one Calibration curve quantified. The amount of functional GFP synthesized is based on the biomass used for the P. mirabilis L-form cells or the E. coli N-form cells (specific activity).

Results:

The values of functional GFP (mg GFP / g dry biomass) listed in Table 2 show the same efficiency of the expression vectors (examples: pMK31GFP (IPTG induction), pMK7GFP (aTC induction) or pMK3c2GFP (constitutive)) for the recombinant Protein formation in the further developed L-shape strains as for already established N-shape strains. -cσli expression systems and production lines.

Table 2: Comparison of the synthesis efficiency for GFP from different vector constructs in P. mirabilis LVIWEI and E. coli RV308 in mg GFP / g dry biomass.

Embodiment 5

Production of soluble, functionally active, recombinant proteins (surface display) with protoplast type L forms from Proteus mirabilis LVIWEI and Escherichia coli LWF + WEI

The example describes the production of recombinant staphylokinase in membrane-bound form. The strains E. coli LWF + WEI and P. mirabilis LVIWEI were used as L-form cells. Staphylokinase is a medically important plasma activator (15 kDa), which can be synthesized by L-form cells as an extracellular, soluble, functionally active, recombinant gene product (Sieben, S., dissertation, University of Jena, 1998). In the translocation process, the 27 amino acid signal peptide is proteolytically separated.

material and methods

In the first step, the DNA sequence (Behnke, D. and Gerlach, D., Mol. Gen. Genetics 1987, 210, 528-534) of the mature protein (amino acids 28-163) by means of PCR (Boehringer, Expand High Fidelity PCR kit) amplified. The saT construct is modified by selection of suitable primers in order to effect the subsequent fusion with the membrane anchor DNA sequences via a PstI site at the 5 'end and the integration into the expression plasmid pF003-Kan via a HindIII site Allow 3 'end (Tab. 1). This saTc fragment is the basis for all fusion proteins. By inserting the Pstl interface, a spacer sequence of two amino acids is inserted simultaneously between membrane anchor and Sak in all constructs.

In the second step, membrane anchor sequences are made available. The helix 1 (amino acids 1-51; LacYHl) and the helices 1-3 (amino acids 1-127; LacYHl-3) of the lactose permease LacY from E. coli are used as such anchor sequences. Other Anchor sequences are helix 1 (amino acids 1-74; SecYHl) and helices 1-3 (amino acids 1-153, SecYHl-3) of the preprotein translocase SecY from E. coli and helix 1 (amino acids 1-34; CcmAHl) of the swarm protein CcmA from P. mirabilis plus an additional spacer of 5 amino acids in length. The corresponding exact sequences are shown in Figure 7. The DNA of the membrane anchor is isolated by PCR from genomic DNA from E. coli DH5θ6 and P. mirabilis VI (Quiagen Genomic DNA Handbook, 1997). For this purpose, primers (Tab. 3) are used which enable integration into the expression plasmid pF003-Kan via a Ndel interface inserted at the 5 'end and fusion with the saJc fragment via a PstI interface inserted at the 3' end ,

Table 3: Overview of primers used in the amplification and modification of the fusion fragments.

In the third step, the sak fragment is cloned into the vector pF003, amplified and then fused in the expression vector with the various modified membrane anchor fragments (Tab. 4; Fig. 8). The membrane anchor-sa./c-fusion genes are under the control of the tac promoter and are therefore inducible by IPTG (isopropyl-β-D-thiogalactopyranoside).

Table 4: Overview of the fusion partners used and the expression plasmids formed

The expression plasmids of the pF series described in Table 4 are then used in step 4 to transform into the L-form cells of P. mirabilis LVIWEI and E. coli LWF + WEI. The PEG method is used to transform (Gumpert et al., Loc. Cit.). Isolation of the transformants is carried out on BHI agar plates with additions of horse serum (8%), yeast extract (0.5%) and kanamycin (0-50 μg / ml). Individual transformant colonies are then transferred to BHI agar plates with the same additions of serum and yeast extract as well as kanamycin (50 μg / ml) and passaged 1-3 times until dense growth is achieved as colonizing grass. The liquid culture of the transformants is obtained in such a way that an agar block with abundant colony growth is introduced into 30 ml of BHI medium with additions of yeast extract (0.5%) and kanamycin (50 μg / ml) and incubated with shaking (37 ° C.) becomes. After 2-4 passages under the same growth conditions, liquid cultures are obtained which lead to cell concentrations of Grow 10 / ml. In the case of the transformants of E. coli LWF + WEI, the additions of kanamycin are lower (1-5 μg / ml).

In step 5, the liquid culture of the transformant is stimulated to synthesize the fusion protein and separated into the fractions culture medium (supernatant), L-shape cells, L-shape membranes and cytoplasm. To do this, transformants, e.g. P. mirabilis LVIWEI (pFCcmAHl-Sak) in glass flask (100 ml) or fermenter (21 net volume) in BHI medium with additions of yeast extract (0.5%) and kanamycin (50 μg / ml) incubated (37 ° C). After 2-6 hours, the addition of IPTG (3 mM) induced the gene expression from the fusion proteins. Samples were taken from the cultures after 8, 24 and 48 hours. The cells are separated by centrifugation (6000 g, 10 min) and the cells as pellet and the culture medium as supernatant.

The cells are once in sucrose solution (0.4 M) in dist. Washed water and then disrupted to separate cytoplasm and membranes. The cells of P. mirabilis LVIWEI are disrupted by ultrasound treatment with a Branson Sonifier 240. The cells are resuspended in TRIS / HC1 buffer (0.05 M, pH 7.0) with the addition of MgS0 ₄ (0.1%) (OD at 600 nm around 10, cell concentration around 10 / ml, 10 ml sample amount) and sonicated for 1 - 3 min with energy level 3, the glass vessel being in an ice bath. By checking samples in a phase contrast microscope (magnification 2000 x), the point in time at which the cells are destroyed and only membrane vesicles are present is determined.

In the case of the transformant cultures of E. coli LWF + WEI, the cells are disrupted by osmotic lysis. The cells washed with 0.4 M sucrose are resuspended in TRIS / HCl buffer (0.05 M, pH 7.0) with additions of 0.1% MgSO ₄ and 30 μg / ml DNAse (Boehringer Mannheim) (cell concentration 10 / ml) and left at room temperature. Continuous microscopic control again determines the point in time Cell lysis determined. The suspensions thus obtained are then used to separate the membrane vesicles from the cytoplasm by ultracentrifugation at 80,000 g in an Optima XL80 centrifuge (Beckmann).

In the 6th step, the biochemical and functional detection of the gene product in the 4 fractions takes place. For this purpose, 30 μl sample is separated in a Western blot (Ausubel, FM 1999; Current Protocols in Molecular Biology) in the SDS gel (13 - 15%) and the proteins after transfer to a PVDF membrane (Millipore) with staphylokinase-specific primary antibodies and secondary antibodies, which are coupled to alkaline phosphatase and can thus cause a color reaction.

The milk agar plate test is used to demonstrate the functional activity. In agar plates (15 cm in diameter), which are washed with aqua dest. Agar (30 ml, 1.5%) are filled with additives of skimmed milk (10%) and plasminogen (10 ^" μg / ml; Boehringer Mannheim), holes (9 mm in diameter) are punched into which 50 μl of the samples are added After 2 - 18 hours of incubation (37 ° C) the clearing zones are measured. The plasminogen is activated by biologically active staphylokinase, and the resulting plasmin cleaves the milk casein and leads to clearing zones around the punch hole. By comparison with staphylokinase The biological activity of staphylokinase can thus be determined quantitatively.

In the 7th step, the localization of the fusion protein on the outside of the L-shape membrane is examined by trypsin digestion and by freeze-fracture electron microscopy with immunogold labeling on the replicon. In addition, the membrane integrity of the fusion protein is proven by the detection of the reconstitution in micelle-forming detergents such as octylglycoside or Triton X100. Results

Fig. 7 documents the amino acid and nucleotide sequences of the membrane anchors and the fusion proteins. With the sequence of the mature staphylokinase, which corresponds to amino acids 28-163 of the complete protein (unlabeled amino acid and nucleotide sequence regions), the following membrane-spanning were inserted N-terminally via an inserted PstI interface (sequence regions bold, italic, underlined) and a corresponding short amino acid linker Domains merged (sequence regions underlined twice): a) Helix 1 (amino acids 1 - 51; LacYHl) of the lactose permease, b) Helices 1 - 3 (amino acids 1 - 127; LacYHl-3) of the lactose permease, c) Helix 1 (amino acids 1 - 74; SecYHl) of the preprotein translocase, d) helices 1 - 3 (amino acids 1 - 153; SecYHl-3) of the preprotein translocase and e) helix 1 (amino acids 1 - 34; CcmAHl) of the swarm protein with an additional spacer sequence of five amino acids (sequence areas bold, italic).

Fig. 8 shows an example of the expression plasmid pFLacYHl-3-Sak for the synthesis of recombinant membrane-bound staphylokinase with L-form cells from E. coli LWF + WEI. Ptac: tac promoter; lacYHl-3: Helices 1-3 of lactose permease (As 1-127); sak: gene for staphylokinase (As 28-163); Spacer: 2 As; lacYHl-3-εak: fusion protein; rrnBT: transcription terminator of the rrnB operon; can: kanamycin resistance cassette; ori: replication origin of pBR322; laclq: Lac repressor with a modified promoter.

Fig. 9 documents the synthesis of the membrane-bound fusion poteins LacYHl-Sak and LacYHl-3-Sak and explains schematically the principle of the surface display with E. coli LWF + WEI. a: Western blot analysis with Sak-specific immunostaining; lane 1, molecular weight standard; lane 2, Sak standard; lane 3, membrane fraction of LacYHl-Sak expressing cells; lane 4, membrane fraction of cells expressing LacYhl-3-Sak, b: principle of Anchoring of the fusion proteins in the phospholipid bilayer of the membrane; 5, staphylokinase portion; 6, lactose permease content (trans-embrane helices in the phospholipid bilayer).

1. With the methods used, the gene sequences of the integral membrane anchor domains (Helix 1 and Helices 1-3) can be derived from the lactose permease LacY, from the preprotein translocase SecY from E. coli and from the swarm protein CcmA (Helix 1) P. mirabilis (Fig. 7) are fused with the staphylokinase gene so that they can be integrated into the plasmid pF003-Kan (Fig. 8).

2. The novel membrane anchor staphylokinase gene constructs LacYHl-Sak, LacYHl-3-Sak, SecYHl-Sak, SecYHl-3-Sak and CcmAHl-Sak can be controlled by IPTG induction in the E. coli LWF + WEI and P. strains. mirabilis LVIWEI overexpressed without inhibiting cell growth and damaging or lysing the cells.

3. The gene products of the membrane anchor-staphylokinase fusion proteins are formed in such quantities by the L-form transformants that they are shown in the SDS gel and Western blot as specifically colored bands. In Fig. 9a representative of all fusion proteins, the successful expression of the fusion proteins LacYHl-Sak and LacYHl-3-Sak in E. coli LWF + WEI is shown by means of Western blot analysis with Sak-specific antibodies. The bands correspond to the molecular weights to be expected (LacYHl-Sak = 20.8 kDa, LacYHl-3-Sak = 27.9 kDa). Approximately 5-50 mg / 1 fusion product was formed. Fig. 9b illustrates the principle of membrane anchors and fusion proteins. The expression of the fusion proteins SecYHl-Sak (23.7 kDa) and SecYHl-3-Sak (32.1 kDa) could be demonstrated in E. coli LWF + WEI using the same methods. However, SecYHl-3-Sak is only expressed in small amounts. P. mirabilis LVIWEI is less suitable for the expression of fusion proteins with heterologous membrane anchors from E. coli. The expression however, the fusion product CcmAHl-Sak in P. mirabilis LVIWEI was very successful. The amount of membrane bound staphylokinase was in the range of 100 mg / 1.

4. The gene products are predominantly or exclusively localized in the membrane fractions. Only small amounts can be found in the cytoplasm or in the medium supernatant. In the case of fusion proteins with a helix (Hl), the amount of staphylokinase synthesized is significantly higher (3 - 10 times) than in the case of constructions with 3 helices (Hl-3). It remains almost completely bound to the L-shape membrane. The staphylokinase fused with three helices can only be detected in membrane-bound form.

5. The staphylokinase localized in the membrane fractions is functionally active. Active staphylokinase was detected using the milk agar test.

6. The staphylokinase molecules are on the outside of the L-shape membrane. In addition to the positive functional activity, this was demonstrated by the loss of staphylokinase after proteolytic degradation with trypsin, by reconstitution experiments in Triton X100 and octylglycoside, as well as by immunogold staining and subsequent electron microscopy. It can be concluded from the mechanical and chemical treatments of the membranes (shear forces during cultivation, washing with TRIS / HCl buffer, preparation and washing of the membrane) that the staphylokinase molecules remain very firmly bound to the L-form membrane.

The results demonstrate the development of new surface display systems with which membrane-bound and fusion proteins from membrane anchor peptides and soluble proteins can be synthesized in a controlled manner and produced in relatively large quantities in L-shape membrane vesicles. In comparison to the previously known bacterial surface display systems, the Advantages of this system in that L-form membranes are relatively easy to obtain in pure form, that immunoreactive components (eg LPS, muramyl peptides, fimbriae, flagella) are largely absent, that extracellular proteases are missing, that only translocation is available for the surface display the cytoplasmic membrane requires that relatively large amounts of the fusion protein be exposed on the outside of the L-shape membrane and that the protein product remain bound to the membrane as functionally active molecules.

The L-shape surface display system opens up new ways of studying structure-function relationships and cell-cell interactions as well as developing new and alternative vaccination strategies and diagnostic test systems.

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² In the cases referred to in Rule 10.2 (a) (ii) and (iü), refer to the most recent viability test 'Mark with a cross the applicable box.

⁴ Fill in if the information has been reqnested and if the results of the test were negative.

Form DSMZ-BP / 9 (sole page) 0196 INTERNATIONAL FORM

Institute for Molecular Biotechnology e.V. Beutenbergst. 11

07708 Jena RECEIPT IN THE CASE OF AN ORIGINAL DEPOSIT issued pursuaπt to Rule 7.1 by the INTERNATIONAL DEPOSITARY AUTHORITY identified at the bottom of this page

I. IDENTIFICATION OF THE MICROORGANISM

Identification reference given by the DEPOSITOR: Accession number given by the INTERNATIONAL DEPOSITARY AUTHORITY: L99WEI

DSM 13364

II. SCIENTIFIC DESCRIPTION AND / OR PROPOSED TAXONOMIC DESIGNATION

The microorganism identified under I. above was accompanied by:

(X) a scientific description

(X) a proposed taxonomic designation

(Mark with a cross here applicable).

III. RECEIPT AND ACCEPTANCE

This International Depositary Authority accepts the microorganism identified under 1. above, which was received by it on 2000 - 03 - 06 (Date of the original deposit) ¹ .

IV. RECEIPT OF REQUEST FOR CONVERSION

The microorganism identified under I above was received by this International Depositary Authority on (date of original deposit) and a request to convert the original deposit to a deposit under the Budapest Treaty was received by it on (date of receipt of request for conversion).

V. INTERNATIONAL DEPOSITARY AUTHORITY

Name: DSMZ-GERMAN COLLECTION OF SIGNATURES) of personfs) having the power to represent the

MIKROORGANISMEN UND ZELLKULTUREN GmbH International Depositary Authority or of authorized official (s):

Address: Mascheroder Weg lb D-38124 Braunschweig> i ^ ^ ~ f, ^ _

Date: 2000 - 03 -10

¹ Where Rule 6.4 (d) applies, such date is the date on which the Status of international depositary authority was acquired. Form DSMZ-BP / 4 (sole page) 0196 INTERNATIONAL FORM

Institute for Molecular Biotechnology e.V. Beutenbergstr. ll

07708 Jena VIABILITY STATEMENT issued pursuant to Rule 10.2 by the INTERNATIONAL DEPOSITARY AUTHORITY identified at the bottom of this page

I. DEPOSITOR II. IDENTIFICATION OF THE MICROORGANISM

Name: Institute for Molecular Accession number given by the

Biotechnology e. V. INTERNATIONAL DEPOSITARY AUTHORITY: Address: Beutenbergstr. 11 DSM 13364

07708 Jena Date of the deposit or the transfer ': 2000 -03 - 06

III. VIABILITY STATEMENT

The viafaility of the microorganism identified under II above was tested on 2 000 - 03 - 06 ² . On that date, the Said microorganism was

(X) ³ viable

{) 'πo longer viable

IV. CONDITIONS UNDER WHICH THE VIABILITY TEST HAS BEEN PERFORMED ⁴

V. INTERNATIONAL DEPOSITARY AUTHORITY

Name: DSMZ-GERMAN COLLECTION OF Signature (s) of person (s) having the power to represent the MIKROORGANISMEN UND ZELLKULTUREN GmbH International Depositary Authority or of authorized official (s):

Address: Mascheroder Weg Ib D-38124 Braunschweig 1 ^^ ^ _J ~ -7 ~ ^ _

Date: 2000-03-10

¹ • Indicate the date of original deposit or, where a new deposit or a transfer has been made, the most recent relevant date (date of the new deposit or date of the transfer).

² In the cases referred to in Rule 10.2 (a) (ii) and (iü), refer to the most recent viability test

³ Mark with a cross the applicable box.

* Fill in if the information has been requested and if the results of the test were negative.

Foim DSMZ-BP 9 (sole page) 0196

Claims

claims

1. A process for the production of modified L-shape bacterial strains, characterized in that

a) one cultivates an L-form bacterial strain adapted to a complex nutrient medium alternately at different temperatures in the temperature range from 20 to 40 ° C., and

b) fermented with increasing hydromechanical load on the cells.

2. The method according to claim 1, characterized in that the L-form bacterial tarry used in step (a) and (b) is a stable protoplast type L-form.

3. The method according to claim 1 or 2, characterized in that the L-form bacterial strain is an L-form of Escherichia coli, Proteus mirabilis, Bacillus subtilis, Bacillus licheniformis, Nocardia asteroides, Pseudomonas stutzeri, Staphylococcus aureus, Streptococcus faecalis, Streptomyces hygroscopic or Thermoactinomyces vulgaris.

4. The method according to claim 3, characterized in that the L-form bacterial strain is an L-form of P. mirabilis LVI, P. mirabilis L99, E. coli LWF +, E. coli LWF- or Bac. subtilis L1 is 70.

5. The method according to any one of claims 1 to 4, characterized in that steps (a) and (b) are carried out in this order.

6. The method according to any one of claims 1 to 5, characterized in that step (a) is carried out in such a way that the temperature alternating between two tempera- ren Tl and T2 varies, wherein Tl remains the same in the course of step (a) and T2 is varied.

7. The method according to any one of claims 1 to 6, characterized in that step (b) is carried out in such a way that the stirring speed is varied with which the fermentation medium is stirred.

8. The method according to any one of claims 1 to 7, characterized in that in steps (a) and (b) the nutrient medium from brain-heart-infusion-broth (BHIB), Todd-Hewitt-broth (THEB), tryptic Soy-broth (TSOYB) and L-broth (LB) is selected.

9. The method according to any one of claims 1 to 8, characterized in that the ventilation rate is varied from 0.2 to 1 volume of air / minute / volume of medium.

10. A method for obtaining modified L-form bacterial strains, characterized in that an L-form bacterial strain adapted to a complex nutrient medium is created by mutations in the genes recA, hsdR / S, relA, supE and / or by introduction of amber and ocher mutants recombination, modification and restriction and / or modified by inserting transcription and translation control genes, such as IacJ and IacUV-T7, into the chromosome.

11. L-form bacterial strain, obtainable by a process according to claims 1 to 10.

12. L-form bacterial strain according to claim 11, characterized in that it from the P. mirabilis LVIWEI (depository number DSM 13363); P. mirabilis L99WEI (accession number DSM 13364), E. coli LWF + WEI (accession number DSM 13362) and B. subtilis L170WEI (accession number DSM 13361) existing group.

13. A method for producing gene products, characterized in that an L-form bacterial strain according to one of claims 11 to 12 is transformed with a nucleotide sequence coding for a gene product, then the transformed L-form bacterial strain is cultivated and for expression of the gene product stimulates and finally the gene product is isolated.

14. The method according to claim 13, characterized in that for the transformation a vector system is used which contains the nucleotide sequences coding for the gene product linked to regulatory sequences.

15. The method according to claim 13 or 14, characterized in that the gene product is a membrane-bound protein.

16. The method according to claim 15, characterized in that the product gene is linked to an additional gene sequence which codes for a signal peptide, a sequence of a transmembrane region of membrane proteins or a hydrophobic amino acid sequence.

17. The method according to claim 16, characterized in that the additional gene sequence for a signal peptide that is not cleaved from the product protein by prokaryotic signal peptidases, for a transmembrane helix of integral membrane proteins, for a homologous or heterologous trans-embrane region of prokaryotic membrane proteins, for the eukaryo- table signal peptide of the SERP protein or a hydrophobic amino acid sequence encoded with 8 to 150 amino acids.

18. The method according to any one of claims 13 to 17, characterized in that the gene product is a protein which can be used as a medicament or diagnostic agent, an immunodeterminant, an enzyme inhibitor, an enzyme activator, a receptor Precursor protein or an enzyme or a signal transmission protein.

19. A process for the production of protein bound to cell surfaces, characterized in that one transforms an L-form bacterial strain with a nucleotide sequence, which for a gene product and an associated signal peptide, an associated sequence of a transmembrane region of membrane proteins or an associated one Hydrophobic amino acid sequence is encoded, the transformed L-form bacterial strain is then cultivated and stimulated to express the gene product, and the gene product is finally isolated in the form bound to the cells of the L-form strain.

20. A process for the production of outer membrane protein (Omp) of Gram-negative bacteria, characterized in that an L-form bacterial strain is transformed with a nucleotide sequence which is an associated sequence for an Omp and an associated signal peptide a transmembrane region of membrane proteins or an associated hydrophobic amino acid sequence, then the transformed L-form bacterial strain is cultivated and stimulated to express the gene product and the gene product is finally isolated.

21. The method according to claim 20, characterized in that the

Omp is an Omp with a β-sheet structure.

22. The method according to claim 20 or 21, characterized in that the signal peptide is a signal peptide for translocation.

23. The method according to any one of claims 18 to 19, characterized in that the gene product is an antigenic determinant of pathogenic organisms, a single chain antibody or antibody fragment, a heterologous enzyme, a polyhistidyl tag or a peptide library.

24. L-form bacterial strain, characterized in that it has recombinant proteins which are anchored to the cytoplasmic membrane of the L-form cells via a signal peptide, a sequence of a transmembrane region of membrane proteins or a hydrophobic amino acid sequence.

25. L-form bacterial strain according to claim 24, characterized in that the recombinant protein is an antigenic determinant of pathogenic organisms, a single chain antibody or antibody fragment, a heterologous enzyme, a polyhistidyl tag or a peptide library.

26. L-form bacterial strain, characterized in that it has recombinant proteins which are omps with a β-sheet structure.

27. Vaccine containing an L-form bacterial strain according to one of claims 24 to 25.

28. Use of an L-form bacterial strain according to one of claims 24 to 26 for the expression of proteins, as a vaccine, for the preparation of an agent for diagnosis and therapy, as a biocatalyst or for interaction screening.

29. Use of an L-form bacterial strain according to one of claims 10 to 11 for the expression of proteins.