EP3245285A1

EP3245285A1 - Combination of bacterial chaperones positively affecting the physiology of a native or engineered eukaryotic cell

Info

Publication number: EP3245285A1
Application number: EP16700765.7A
Authority: EP
Inventors: Denis Pompon; Stéphane GUILLOUET; Jillian MARC; Nathalie GORRET; Carine Bideaux; Christel Boutonnet; Florence BONNOT
Original assignee: Centre National de la Recherche Scientifique CNRS; Institut National des Sciences Appliquees de Toulouse; Institut National de la Recherche Agronomique INRA
Current assignee: Centre National de la Recherche Scientifique CNRS; Institut National des Sciences Appliquees de Toulouse; Institut National de la Recherche Agronomique INRA
Priority date: 2015-01-16
Filing date: 2016-01-15
Publication date: 2017-11-22
Also published as: AU2016207978A1; US20180187204A1; CA2973912A1; KR20170105079A; BR112017015201A2; WO2016113418A1; CN107257851A; JP2018501810A

Abstract

The invention relates to the expression of a specific combination of three bacterial chaperones in a eukaryotic cell, which significantly improves the growth properties thereof and the properties thereof relating to resistance to physicochemical stresses, especially when said cell comprises additional engineering using at least one non-native gene. A preferred combination of chaperones comprises the chaperones GroES and GroEL of E. coli and the chaperone RbcX of Synechococcus elongatus.

Description

COMBINATION OF BACTERIAL CHAPTERONES AFFECTING POSITIVE PHYSIOLOGY

A NATIVE EUCARYOTE CELL OR ENGINEERING

The present invention relates to the field of cellular engineering, in particular eukaryotic cells. More particularly, the invention relates to eukaryotic cells having improved growth and / or metabolic properties, as well as their uses for the production of compounds of interest. In particular, the invention relates to eukaryotic cells expressing a specific combination of chaperones. The invention finds applications in particular in the field of the production of recombinant proteins.

Technological background

There are currently many protein expression systems of interest used in areas as diverse as biotechnology, agri-food, drug industry or diagnostic research, fundamental and / or applied. Among these expression systems, eukaryotic cells and in particular yeasts play an important role, in particular because of their capacity for glycosylation and their ease of cultivation under industrial conditions. These cells, however, have limits, due in particular to toxicity constraints related for example to the accumulation of products of interest (for example a high concentration of ethanol or other alcohol) or to a direct or indirect toxicity of the expressed proteins. or the energy charge required for the presence of expression plasmids.

Summary of the invention

The present invention provides eukaryotic cells with improved performance, allowing the development of optimized expression systems.

As part of a project to introduce a synthetic Calvin cycle into yeast, the inventors surprisingly observed that coexpression in yeast of a set of three bacterial chaperones (RbcX, GroES and GroEL) conferred eukaryotic cells with remarkable metabolic properties, especially in terms of expression and functional folding of heterologous or endogenous proteins. Pursuing their investigations, the inventors have also demonstrated that this combination of chaperones also allowed to accelerate the growth of yeasts and remove the toxic effects of other engineering, for example when PRK kinase is co-expressed in the cell. The inventors have moreover verified and obtained the same effects on the performances on various eukaryotic cells, confirming the interest and the great potential of these unexpected results.

An object of the present invention therefore relates to a eukaryotic cell, characterized in that it expresses RbcX, GroES and GroEL chaperones.

In a particular embodiment, the present invention relates to a transformed eukaryotic cell, characterized in that it contains:

(i) an expression cassette containing a coding sequence for an RbcX chaperone involved in the folding of a RuBisCO enzyme of form I of bacterial origin, under transcriptional control of a suitable promoter;

(ii) an expression cassette containing a sequence coding for a GroES general-interest bacterial chaperone under transcriptional control of an appropriate promoter; and

(iii) an expression cassette containing a sequence coding for a generalized GroEL bacterial chaperone under transcriptional control of a suitable promoter.

The invention also relates to a eukaryotic cell containing:

(i) a coding sequence for an RbcX chaperone under transcriptional control of an appropriate promoter;

(ii) a coding sequence for a GroES chaperone under transcriptional control of an appropriate promoter; and

(iii) a sequence encoding a GroEL chaperone under transcriptional control of a suitable promoter. According to a particular embodiment, the eukaryotic cells of the invention do not contain a coding sequence for the RbcL and / or RbcS subunit of a RuBisCO enzyme of form I of bacterial origin.

The invention notably proposes a yeast transformed as indicated above. The subject of the invention is also the use of a combination of expression cassettes allowing the expression of an RbcX chaperone and GroES and GroEL chaperones, to improve the physiology of a eukaryotic cell, and in particular to increase the growth rate of said eukaryotic cell and / or increase the resistance of said eukaryotic cell to environmental stress and / or increase the resistance of said cell to the toxicity of a compound synthesized by the eukaryotic cell and / or for the production of a recombinant protein.

The subject of the invention is also a biotechnological process for producing at least one compound selected from chemical molecules and proteins, characterized in that it comprises a step of culturing a eukaryotic cell according to the invention under conditions allowing the synthesis, by said eukaryotic cell, of this compound, and a step of recovering said compound.

The invention more particularly proposes a method for producing a recombinant protein comprising (i) inserting a sequence encoding said protein into a eukaryotic cell expressing RbcX, GroES and GroEL, (ii) culturing said cell in conditions permitting the expression of said sequence and optionally (iii) the recovery or purification of said protein.

Brief description of the figure

Figure 1: Kinetics of ethanol production strains lb, 18b, 102, 15, 14b. The error bar represents a standard deviation of 3 independent cultures. detailed description

By working on the expression of certain bacterial chaperone proteins in a eukaryotic cell, the inventors have discovered that, quite surprisingly, bacterial chaperones can be expressed in the cytosol of a eukaryotic cell and retain their chaperone function in said eukaryotic cell. The bacterial chaperone function is added to the cytosolic chaperone function already present in the eukaryotic cell. The inventors have furthermore discovered that the expression of a particular triplet of chaperones, namely the bacterial chaperones GroEL and GroES and the RbcX chaperone, confers on the transformed eukaryotic cell which expresses them properties of particular interest in terms of growth, d expression and functional folding of proteins.

The observed effects require obligatorily the simultaneous presence of the three chaperones mentioned, preferably coming from at least two different microorganisms. If it was known that coexpression of chaperones is likely to improve in a bacterial system the folding of heterologous proteins and therefore potentially the performance of a bioprocess dependent, it was not foreseeable that a specific interorganism combination of three bacterial chaperone proteins, can be particularly effective in being expressed in eukaryotic context. The molecular mechanisms leading to the effects of the invention are currently unknown even if they are probably, at least in part, related to protein folding or control of their intracellular fate. A surprising generalist role is played by the protein of the RbcX family (described in the prior art as specialized for the functional association of the RuBisCO complex of photosynthetic organisms), in the presence of GroES and GroEL chaperones which play complementary roles. This feature of the invention suggests that the observed effect can not be fully attributed to a facilitated folding role and may involve other mechanisms such as modulation of the lifetime of specific proteins, assembly of complexes or modification of their properties, or even specific effects of a nature to be defined.

In this context, the invention therefore proposes to transform eukaryotic cells so that they express a particular triplet of chaperones, namely the bacterial chaperones GroEL and GroES and chaperone RbcX. Such transformed cells may find many applications, especially in the context of the production of recombinant proteins.

The subject of the invention is therefore a eukaryotic cell, characterized in that it expresses RbcX, GroES and GroEL chaperones. The GroEL and GroES chaperones belong to the family of heat shock proteins (HSP). These chaperones are present in many bacteria. In the context of the invention, these chaperones are referred to as "general chaperone" in the sense that they are known to co-act to permit efficient folding of a very large number of proteins (M. mayhew et al. 1996, "Protein folding in the central cavity of the GroEL-GwES chapewnin complex" Nature 1996 Feb 1; 379 (6564): 420-6). According to the invention, the GroEL and GroES chaperones can come from any bacterium that expresses them, and, for example, E. coli (Gene ID: 948655 and 948665), S. elongatus (Gene ID: 3199735). , 199535 and 198035), S. pneumonia (GenBank accession number: AF 1 17741), S. pyogenes (GenBank accession number: SPGROELGN), S. aureus (GenBank accession number: STAHSP) or P. aeruginosa (GenBank accession number ATCC9027). ^The skilled person is perfectly capable of identifying bacteria in the nucleic acid sequences likely coded for either of these chaperones. For information, it should be noted that the sequence similarity of the chaperones (% identical amino acids in the alignment) is 61% between GroEL1 of S. elongatus and GroEL of E. coli; 56% between GroEL2 of S. elongatus and GroEL of E. coli; 63% between GroELl and GroEL2 of S. elongatus.

The cells according to the invention also express the known RbcX chaperone in cyanobacteria and plants to participate in the good assembly of the RbcL and RbcS subunits of Rubisco. In the context of the invention, this chaperone is designated as "chaperone specific" in the sense that this protein is known to play a role in the functional association of protein complexes, as is particularly the case with Rubisco (S Saschenbrecker et al., 2007, "Structure and function of RbcX, an assembly chaperone for hexadecameric Rubisco," Cell 2007 Jun 15; 129 (6): 1189-200). According to the invention, the RbcX chaperone can come from any cyanobacterium expressing it, and, ^for example, from S. elongatus (SEQ ID No. 3), Synechocystis sp. (Kaneko et al., "Sequence analysis of the genome of the unicellular cyanobacterium synechocystis sp. Strain PCC6803.) Sequence determination of the resulting genome and assignment of potential protein-coding regions." DNA Res.3 (3), 109 - 36 (1996)), Anabaena sp. (Li et al., J. Bacteriol (1997), 179 (11), 3793-3796), Microcystis sp., Tychonema sp., Planktothrix sp. gold Nostoc sp. (Rudi et al., J. Bacteriol (1998), 180 (13), 3453-3461).

In the context of the invention, a "chaperone activity" refers to a protein folding action and / or the functional association of protein complexes. In a particular embodiment of the invention, the chaperones used come preferentially from two different organisms. According to the invention, the chaperones can come from one or more different bacteria. Preferably, the three chaperones originate from at least two distant Gram negative bacterial species, at least one of which is a cyanobacterium.

According to another particular embodiment of the present invention, at least one of the general-interest chaperones GroES and GroEL does not come from a cyanobacterium or from another bacterium expressing an RuBisCO complex. According to the invention, the GroES and GroEL chaperones can come from the same bacterium or from two different bacteria. In a particular embodiment, the GroES and GroEL chaperones come from E. coll.

In a particular embodiment, the GroES and GroEL chaperones come from E. Coli and the chaperone RbcX comes from Synechococcus elongatus.

In another embodiment, the three chaperones GroES, GroEL and RbcX come from Synechococcus elongatus. In such a case, the transformed cell can express either one or the two isoforms (GroEL1 and GroEL2) of the GroEL chaperone, preferably both isoforms.

In the context of the invention, it is considered that a protein "comes" from a given organism as soon as it has an amino acid sequence identity greater than 95% and the same function as the relevant protein of said organism. In the present text, "GroES" and "GroEL" denote any protein exhibiting chaperone activity and having between 65 and 100% amino acid identity with GroES and GroEL of E. coli K 12, respectively. Alternatively, "GroES" and "GroEL" denote general chaperones with a lower percentage of identity, and in particular between 55 and 65%, and more particularly between 56 and 63%, such as general chaperones of S. elongatus. The chaperone activity of a variant of the general chaperons GroES and GroEL of E. coli can be verified for example by substituting in the various examples described below, the expression cassette coding for GroES or GroEL native to E. coli by chaperone variants to be evaluated. The RbcX chaperone is very far from GroEL and GroES and its sequence can not be aligned with the sequences of these two chaperones.

In the present text, the term "RbcX" denotes any protein, in particular of cyanobacteria, having a chaperone activity and having more than 50% amino acid sequence identity with the RbcX chaperone encoded by the sequence SEQ ID No: 3 and retaining the chaperone activity specific for this protein. The specific chaperone activity can be verified in a yeast expressing the RbcL and RbcS subunits of the RuBisCO of S. elongatus, replacing the expression cassette including the sequence SEQ ID No. 3 by any other sequence to be evaluated, and in measuring by an in vitro test on cell extracts the RuBisCO activity thus obtained.

Preferably, the present invention is implemented with a chaperone RbcX whose amino acid sequence identity with chaperone RbcX encoded by SEQ ID No: 3 is greater than 80%, preferably greater than 90%, more preferably greater than at 95%, still more preferably above 99%.

The invention can be implemented with any type of eukaryotic cell, originating from a unicellular or multicellular organism. In particular, the combination of chaperones according to the invention can be expressed in a yeast cell, fungus, plant, animal such as a mammal, etc.

In particular, the present invention relates to a transformed yeast expressing a specific chaperone RbcX, a general bacterial chaperone GroES, and a generalized bacterial chaperone GroEL.

More particularly, the present invention relates to a transformed yeast, characterized in that it contains:

(i) an expression cassette containing a coding sequence for the RbcX chaperone involved in the folding of a form I enzyme of bacterial origin RuBisCO, under transcriptional control of a suitable promoter;

(ii) an expression cassette containing a sequence encoding a general Groes bacterial chaperone, under transcriptional control of an appropriate promoter; and (iii) an expression cassette containing a coding sequence for a generalized bacterial chaperone GroEL, under transcriptional control of a suitable promoter.

The invention can be implemented with any yeast of interest. Advantageously, the yeast is chosen from Saccharomyces, Yarrowia and Pichia. For example, the yeast transformed according to the invention is a Saccharomyces cerevisiae cell. In another example, the yeast transformed according to the invention is a Yarrowia lipolytica cell, or a Pichia pastoris cell.

The use of Pichia pastoris is particularly interesting for the production of recombinant proteins. Indeed, Pichia has a eukaryotic protein expression system that is very efficient both for secretion and for intracellular expression. It is particularly suitable for large scale production of recombinant eukaryotic proteins. In particular, Pichia can be used for the production of high-yielding excreted proteins in order to reduce costs and production times compared to those associated with mammalian cell expression systems. Yarrowia lipolytica is also suitable for use in the production of recombinant proteins. Indeed, Yarrowia has (i) high density growth, (ii) high secretion, (iii) lack of alkaline protease EPA and (iv) ability to produce S. cerevisiae invertase allows the use of sucrose as a carbon source (Nicaudet al., 1989). This last property is particularly interesting in the case of industrial production, because this strain can grow efficiently on inexpensive substrates such as molasses.

The invention also relates to a eukaryotic cell derived from a multicellular organism, such as an animal cell and in particular a transformed mammalian cell expressing a specific RbcX chaperone, a generalized bacterial chaperone GroES, and a generalized bacterial chaperone GroEL.

In an exemplary embodiment, such a eukaryotic cell is transformed to contain:

(i) an expression cassette containing a coding sequence for the RbcX chaperone involved in the folding of a form I enzyme of bacterial origin RuBisCO, under transcriptional control of a suitable promoter; (ii) an expression cassette containing a sequence encoding a general Groes bacterial chaperone, under transcriptional control of an appropriate promoter; and

(iii) an expression cassette containing a coding sequence for a generalized bacterial chaperone GroEL, under transcriptional control of a suitable promoter. The invention relates in particular to a transformed CHO cell expressing the triplet of chaperones according to the invention.

According to the invention, the genes encoding the GroEL, GroES and RbcX chaperones are introduced into eukaryotic cells in a form allowing their expression in said cells. Thus, the sequences coding for chaperones are associated with promoter sequences allowing their transcription. In one embodiment, the same promoter sequence is associated with the coding sequences for the three chaperones. In another embodiment, the RbcX chaperone is associated with a particular promoter different from the promoter (s) associated with the GroEL and GroES chaperones. In another embodiment, each chaperone is associated with a different particular promoter. Promoters useful in the context of the present invention include constitutive promoters, i.e., promoters that are active in most cellular states and environmental conditions, as well as inducible promoters that are activated or repressed by exogenous physical or chemical stimuli. thus inducing a variable level of expression depending on the presence or absence of these stimuli. For expression cassettes in yeasts, examples of constitutive promoters are those of the genes TEF1, TDH3, PGI1, PGK, ADH1. Examples of inducible promoters are the tetO-2, GAL10, GAL10-CYC1, PHO5 promoters. Preferably, the promoters used will be different from one cassette to another. Expression cassettes of the invention further include the usual sequences such as transcriptional terminators, and optionally other transcriptional regulatory elements. The expression cassettes according to the invention may be inserted into the chromosomal DNA of the host cell, and / or carried by one or more extra-chromosomal replicon (s). The relative stoichiometry of these proteins is likely to play an important role in the optimal implementation of the present invention. The coexpression systems described in the experimental section below are particularly relevant in this regard. The invention is however not limited to the use of these systems, and it can be implemented with any expression variant of the elements mentioned having effects at least equivalent, as they can be measured, for example, by measuring the growth of a cell transformed in a standard medium for said cell. According to an advantageous embodiment, the three expression cassettes form a continuous block of genetic information. It may also be advantageous for the expression cassettes of the three chaperones to be carried by a single episomal genetic element. A particularly interesting aspect of the present invention is therefore a unique "genetic plug-in" (continuous sequence of DNA) carried by an episomal element at the origin of centromeric replication. The transformation by this element is sufficient to introduce the properties of interest in wild yeasts or any engineering.

According to the invention, the genes coding for each chaperone can be introduced in one or more copies into the cell. In particular, it is possible to introduce one, two, three or more cassettes containing a sequence coding for GroES, one, two, three or more cassettes containing a coding sequence for GroEL, and one, two, three or more cassettes containing a sequence. coding for RbcX. Similarly, a cassette may contain several copies of a Sequence encoding GroES, GroEL or RbcX. In the case where several copies of genes coding for a chaperone are introduced into the cell, preferentially the same sequence is used each time, that is to say from the same bacterium. It is otherwise possible to use sequences from different bacteria.

As mentioned above, the cells according to the present invention have improved properties (growth rate, resistance, production capacity, etc.). These cells are therefore particularly useful for the production of proteins or other compounds, or for the improvement of fermentation processes. Protein production

Also, the invention also relates to a eukaryotic cell transformed to express a combination of chaperones as described above and which furthermore comprises at least one expression cassette for a heterologous protein other than said chaperones, and / or which has has undergone sequence engineering modifying the level of expression and / or the sequence of an endogenous protein. According to a preferred embodiment of the invention, the transformed eukaryotic cell is a yeast. According to another preferred embodiment of the invention, the transformed eukaryotic cell is a CHO cell.

The invention therefore also relates to a yeast or a CHO cell transformed to express a combination of chaperones as described above, and containing:

(iv) an expression cassette for a heterologous protein other than said chaperones; and or

(v) having undergone sequence engineering modifying the level of expression and / or the sequence of an endogenous protein. According to the invention, it is possible to use such a transformed cell to produce one or more proteins of interest.

Advantageously, the protein of interest is not Rubisco. Likewise, preferably, the protein of interest is a protein other than PKR. Also, if the transformed eukaryotic cell expresses Rubisco and / or PKR, it advantageously expresses at least one other heterologous protein.

In a particular embodiment, the transformed cell expressing the chaplet triplet GroES, GroEL and RbcX and further modified to express and excrete a recombinant protein.

The present invention also relates to a biotechnological process for producing at least one compound selected from chemical molecules, enzymes, hormones, antibodies and proteins, characterized in that it comprises a step of culturing a transformed cell. as described above, under conditions allowing the synthesis by said cell of this compound, and optionally a step of recovering and / or purifying said compound. The invention also relates to a method for producing a recombinant protein comprising (i) inserting a sequence encoding said protein into a eukaryotic cell expressing the RbcX, GroES and GroEL chaplet triplet, (ii) culturing said cell under conditions permitting the expression of said sequence and optionally (iii) the recovering and / or purifying said protein. Advantageously, said protein is an enzyme or a hormone.

In a particular embodiment, the cell according to the invention is transformed so as to produce at least one heterologous enzyme. For example, the cell is transformed to produce an enzyme selected from endotoxins, such as Bacillus thuringiensis endotoxin, lipases, subtilisins, cellulases and luciferases.

In another particular embodiment, the cell according to the invention is transformed so as to produce at least one molecule of medical interest. For example, the cell is transformed to produce a hormone, a growth factor, an antibody, etc. Preferably, the molecule of medical interest is chosen from erythropoietin, type I and / or II alpha-interferons, granulocyte colony stimulating factors, insulin, growth hormones and tissue plasminogen activators. .

Advantageously, the cell transformed according to the invention has an improved production of the protein or proteins of interest, compared to a recombinant cell that does not express the combination of chaperone of the invention. In the context of the invention, "improved" production is understood in terms of quantity and / or quality. In particular, the transformed cell according to the invention can produce more active and / or more stable proteins of interest, and therefore less likely to be degraded, which allows a greater accumulation of said proteins, compared to the heterologous proteins produced by a protein. recombinant cell not expressing the combination of chaperone of the invention. Thus, the increase in the level of expression of a recombinant protein by a eukaryotic cell transformed according to the invention is explained in particular by a greater stability and therefore a greater accumulation of said proteins in the cell and / or the medium of the invention. culture. In addition, the expression of the combination of chaperones by the transformed cell can advantageously increase the resistance of the recombinant cell to the recombinant proteins it expresses, thereby also contributing to the increase in production yield.

The present invention also relates to the use of a combination of expression cassettes for the expression, in a eukaryotic cell, of the specific chaperone RbcX and the general chaperones GroES and GroEL, for improving physiology and / or performance ( especially the growth rate) of said eukaryotic cell. According to one In a preferred embodiment of this aspect of the invention, the eukaryotic cell whose physiology is to be improved is a yeast. According to another preferred embodiment, said eukaryotic cell has not been transformed to express a sequence coding for the RbcL subunit of a RuBisCO enzyme of form I of bacterial origin, and / or a coding sequence for the sub-unit - RbcS unit of said RuBisCO enzyme.

As discussed above, a combination of expression cassettes allowing the expression of the GroES and GroEL general chaperones and the RbcX-specific chaperone is particularly useful for improving the physiology of a eukaryotic cell that has undergone sequence-altering engineering. expression and / or sequence of an endogenous protein or comprising at least one expression cassette for a heterologous protein other than said chaperones, for example in the form of an episomal genetic element.

In particular, the concomitant expression, in a cell, of the general-interest chaperones GroES and GroEL and of the specific chaperone RbcX makes it possible to increase the growth rate of said cell and / or to increase the resistance of said cell to an environmental stress. , in particular to stress due to the toxicity of an element present in the culture medium of the cell. Another advantageous application is to increase the resistance of the cell to the toxicity of a compound synthesized by itself, and thus the production of a compound of interest.

Many applications of the invention are possible, including all applications related to the improvement of folding or stability (resistance to chemical or thermal agents, intrinsic life) of homologous or heterologous proteins to the transformed eukaryotic cell. It may be proteins in themselves, or of interest in enzymatic catalysis, or because of their intrinsic properties (antibodies, therapeutic proteins, structural proteins with complex breasts, etc.); Applications related to improving the performance of a synthetic or semi-synthetic metabolic chain

(involving proteins of the transformed eukaryotic cell); in this case, the advantage is mainly an improvement in the result of their actions at the level of the production of a product of interest (chemical molecule). This effect can result from the improvement of the folding or the stability but also other phenomena for example subcellular transport, facilitated or modified formation of complexes, modulation of coupling mechanisms, etc. ; The applications resulting from overall positive effects on an organism in terms of growth, viability, adaptability, resistance or recovery to stress, formation of products of interest without the mechanism being known or explicable.

As examples of industrial applications of the invention, mention may be made of, without being limited to: Effect on the folding / stability of proteins

The production of certain recombinant proteins of interest considered difficult or impossible to produce in soluble and functional form can be improved by the implementation of the invention. This can be explained in particular by a correction of the folding defects of said proteins in the eukaryotic cell transformed according to the invention. This can be particularly useful in the areas of health, energy, chemistry, agri-food, etc.

Protection against product-induced toxicity of engineering of interest or intermediates of this engineering

It can be the bio-production of toxic molecules for the host cell or whose production process involves toxic intermediates, for example drugs (hydrocortisone, artemisinic acid or even trictosinide, certain flavonoids for take developed processes) or reactive molecules such as unsaturated ketones, aldehydes (eg vanillin), etc. Other examples are processes producing molecules that become toxic at high concentrations, for example ethanol or other alcohols. Ethanol production for example is limited by the tolerance of yeast strains to high concentrations of alcohol. Other examples relate to the production of highly varied industrial chemical molecules, precursors of common products or chemical intermediates and of course biofuels. It may also be recombinant proteins whose production by a recombinant cell tends to unbalance the metabolism, inducing cell death. The use of a eukaryotic cell expressing the combination of chaperones according to the invention advantageously makes it possible to increase the resistance of the transformed cell to the toxicity induced by the recombinant proteins it expresses. Thermal tolerance

The improvement of the thermal tolerance of specific enzymes or organisms such as yeasts is an important factor for the biotechnological productivity of many poorly soluble molecules for example. Increasing the biomass of a microorganism produced from a fixed amount of carbon source

These are effects that are not understood at the molecular level but are observed in the first experiments reported below.

As mentioned above, the present invention also relates to a nucleic acid molecule comprising:

(ii) an expression cassette containing a sequence encoding a general Groes bacterial chaperone, under transcriptional control of an appropriate promoter; and

(iii) an expression cassette containing a coding sequence for a generalized bacterial chaperone GroEL, under transcriptional control of a suitable promoter.

An example of such "genetic plug-in" is a continuous DNA sequence comprising the three cassettes mentioned above (in any order), carried by an episomal element causing centromeric replication.

The experimental part below illustrates the invention without however limiting it, by presenting:

The constructions realized and the methods implemented (Example 1);

A first series of tests comparing the effect of different combinations of chaperones on the reconstruction of the activity of a type I RuBisCO constituted by the assembly of 16 peptide chains belonging to two different types. The expression of different combinations of chaperones were combined with the expression of the RbcL and RbcS polypeptides of a "RuBisCO type I". This made it possible to analyze the role of the chaperone combination on the RuBisCO activity measured in vitro on yeast cell extracts (Example 2);

A second series of tests involving coexpression of chaperone systems in yeast conditionally expressing S. elongatus phophoribulokinase (PRK). In the absence of the invention, the induction of PRK expression induces a major toxic effect on the yeast, ranging from very slow growth to total lethality (> 99.99%) according to S. cerevisiae strains. and the culture conditions (medium, oxygen level, pH). The exemplification illustrates that the invention "cures" this morbid state without thereby interfering with the activity of the PRK enzyme which remains fully active (Example 3);

A third series of tests demonstrating that the invention restores a level of wild growth in a strain carrying autotrophies complemented by even neutral plasmids (not leading in themselves to the expression of other functions than their own replication). This situation is typical of metabolic engineering involving episomal genetic elements. In the example, the invention completely corrects the negative impact on growth related to the presence of episomal genetic structures (Example 4); and

Another series of tests illustrating that the cells of the invention are particularly useful for the production of compounds and in particular of recombinant proteins (Example 5).

EXAMPLES

In the examples below, and unless stated otherwise, the same acronyms are used from one table to another and from one experiment to another to designate the same elements.

Example 1: Materials and methods - Construction of the "CHAPERONNES plug-in" and vectors - Constructions of the different strains - Methods of culture and measurement

1.1. Construction of "CHAPERONNES plug-in" and vectors for S. cerevisiae

Some constructs described below allow the expression of the two RbcS and RbcL subunits of RuBisCO (pFPP45) and that of phosphoribulokinase PRK (pFPP20) of Synechoccocus elongatus pCC6301. Other constructions described below have been realized in order to make it possible to elaborate, from a single expression vector, variable combinations of expression of the RbcX specific chaperone of Synechoccocus elongatus and general chaperones of E. coli GroES (Gene ID: 948655), GroEL (Gene ID: 948665) or their counterparts GroES (Gene ID: 3199735), GroEL 1 (Gene ID: 3199535) and GroEL2 (Gene ID: 3198035) of Synechoccocus elongatus.

Synthetic genes encoding the RbcS (Gene ID: 3200023) and RbcL (Gene ID: 3200134) subunits and the RbcX specific chaperone (Gene ID: 3199060) of the RuBisCO of Synechoccocus elongatus pCC6301, and optimized for expression in yeast, were prepared and cloned into plasmid pBSII (Genecust). Optimized variants for yeast expression, in which an HA tag has been added at the 3 'end of the coding sequence, have also been constructed. The sequences of these synthetic genes (without the HA tag) are respectively indicated in the attached sequence listing under the numbers SEQ ID NO: 1 to SEQ ID NO: 3.

Similarly, synthetic genes encoding phosphoribulokinase PRK (SEQ ID NO: 4) (pFPP20), as well as general chaperones GroES (SEQ ID NO: 5), GroEL1 (SEQ ID NO: 6) and GroEL2 (SEQ ID NO: 7) of Synechoccocus elongatus pCC6301, and optimized for expression in yeast, were constructed and cloned.

Sequences coding for E. coli GroES and GroEL chaperones were amplified from E. coli cultures. coli and cloned into the plasmid pSC-B-amp / kan (Stratagene). Sequences recovered from the cloning vectors were introduced into yeast expression vectors. These host vectors are listed in Table I below.

Table I: List of vectors used

Note: pGAL10-CYCl: synthetic promoter composed of the UAS of the GAL10 gene and the transcription initiation of the CYCl gene (POMPON et al, Methods Enzymol, 272, 51-64, 1996). The expression cassettes thus obtained are listed in Table II below.

Table II: Expression cassettes

In some vectors, 2 or 3 cassettes have been inserted. For this, the plasmids were amplified in Escherichia coli DH5a bacteria and prepared by maxiprep, and then digested with appropriate restriction enzymes. Finally, the fragments are integrated into the host vectors by T4 ligase ligation (FERMENTAS) or by homologous recombination directly in yeast. The list of vectors constructed is shown in Table III below.

Table III: expression vectors

1.2. Construction of different strains of S. cerevisiae

The various plasmids above were constructed so as to allow the expression of individual components or an association of these components within yeast strains. Different vectors or combinations of vectors have therefore been used to transform several S. cerevisiae yeast strains (W303.1B, FY1679 and CEN.PK 1605). CEN.PK 1605 is the prototrophic version of strain 1605. It is therefore a positive control of "physiological behavior". Each number, compiled in the first column of Table IV below, corresponds to the association of vectors described on the corresponding line of the same table. Thus for each of the strains used, the associated reference number provides the information of the reconstructed engineering. Only CEN.PK 1605 strains have been exemplified (Table IV) for the sake of clarity, but the nomenclature is the same for the other two strains. _^ "

Table IV. Combination of plasmids and strains (references to Table III.)

No. Proteins expressed

Strain

Vector Vector Vector

Rbc Rbc Rbc PRK GroE GroE Combination 1 2 3

parent S L X syn S L n

CEN.PK PYEDP pCM18 pFPP1

1 b

1605 51 5 3

CEN.PK pCM18 pFPP5 E. E.

2 pFPP45 X X X

1605 5 6 coli coli

CEN.PK pFPP5 E. E.

3 pFPP45 pFPP20 X X X syn

1605 6 coli coli

CEN.PK pFPP5

4 pFPP45 pFPP20 X X X syn

1605 3

CEN.PK pCM18 pFPP5

5 pFPP45 X X X

1605 5 3

CEN.PK PYEDP pCM18 pFPP5

12 X

1605 51 5 3

CEN.PK PYEDP pCM18 pFPP5 E. E.

13b X

1605 51 5 6 coli coli

CEN.PK PYEDP pFPP5

14b pFPP20 X Syn

1605 51 3

CEN.PK PYEDP pFPP5 E. E.

15 pFPP20 X syn

1605 51 6 coli coli

CEN.PK pCM18 pFPP1

16b pFPP45 X X

1605 5 3

CEN.PK pFPP1

17b pFPP45 pFPP20 X X syn

1605 3

CEN.PK PYEDP pFPP1

18b pFPP20 syn

1605 51 3

CEN.PK L2

101 pFPP45 pFPP20 pEB08 X X X Syn Syn

1605 syn CEN.PK PYEDP EE

102 pFPP20 pFB09 Syn

1605 51 coli coli

CEN.PK E. E.

102b pFPP45 pFPP20 pEB09 X X syn

1605 coli coli

CEN.PK PYEDP pCM18 E. E.

103 pFB09

1605 51 5 coli coli

(Syn: Synechoccocus elongatus, L2 syn: Groel2 Synechoccocus elongatus, Ll syn: Groel Synechoccocus elongatus)

Notes on some tables:

1. pCM 185: Commercial Plasmid (ATCC 87659)

2. pFL36: Commercial Plasmid (ATCC 77202)

3. PYeDP51: Plasmid "empty", described in the following article: Urban P, C Mignote, Kazmaier M, Delorme F, Pompon D. Cloning, yeast expression, and char act of the coupling of distantly related Arabidopsis thaliana NADPH -cytochrome P450 reductases with P450 CYP73A5. J Biol Chem. 1997 Aug 1; 272 (31): 19176-86.

4. GroES E. coli Gene ID: 6061370; GroEL E. coli Gene ID: 6061450

5. S. Cerevisiae Strain CEN.PK 113-7D: Prototrophic Mat

6. S. Cerevisiae Strain CEN.PK 1605: Matte HIS3leu2-3.112trpl-289 ura3-52 MAL.28c. Strain resulting from CEN.PK 113-7D

7. Other abbreviations refer to the S. cerevisiae genes described in the databases

8. Synthetic genes: Synechoccocus elongatus genes encoding the RuBisCO subunits, the RuBisCO assembly specific chaperone (RbcX), the PRK and the GroES, GroEL1 and GroEL2 general chaperones were synthesized after proprietary recoding for yeast using an inhomogeneous and cloned codon bias in pCC6301 (commercial). The coding sequences of these proteins (after recoding) are presented in the appendix (SEQ ID No: 1: coding sequence of RbcS, SEQ ID No: 2: coding sequence of RbcL, SEQ ID No: 3: coding sequence of RbcX, SEQ ID No: 4: PRK coding sequence, SEQ ID No: 5: GroES coding sequence, SEQ ID No: 6: GroEL1 coding sequence, SEQ ID No: 7: GroEL2 coding sequence). 9. The coding sequences of the E. coli GroES and GroEL chaperones were amplified from the bacterium, cloned into pSC-B-amp / kan (Statagene) and mounted without recoding into the expression vectors (see above). .

10. The recoded sequences of the cDNAs encoding the chaperonins of Synechoccocus elongatus were inserted by homologous recombination into the previously linearized pUC57 vector by cotransforming the two molecules in the yeast. In the same way the ORFs were amplified by PCR from the previous constructions, generating homologous flanking regions to the promoters and terminators carried by the pFPP56 vector. This thus allowed cloning by homologous recombination by co-transforming this PCR product in a yeast strain with the previously linearized vector pFPP56, generating the different expression vectors described in Table III according to the cassettes described in Table II.

1.3. Construction of different strains of Saccharomyces cerevisiae with chaperones of different origins

Chaperones from different bacteria were evaluated. Thus, combinations including proteins from the same species (S. elongatus) were also tested, combining RbcX from S. elongatus with GroES and GroEL 1 and / or GroEL2 with S. elongatus.

Table V: Expression cassettes

Names Promoter Open Reading Phase Terminator Label

CASE 19 TEF1 p RbcX S. elongatus optimized Without PGKt

CAS21 PGM p GroES E. coli Without CYC1t

CAS22 TDH3p GroEL E. Coli Without ADH1t

CAS23 PGM p GroES S. elongatus optimized without CYC1t

CAS24 TEF2p GroEU S. elongatus optimized without TEF1t

CAS25 TDH3p GroEL2 S. elongatus optimized without ADH1t _^ "

Table VI: Expression vectors

Table VII: Combination of plasmids and strains

Synechoccocus elongatus; L2 syn: GroEL2, synL syn: GroELl Synechoccocus elongati

1.4.Constructions of Pichia pastoris strains

In order to maintain a functional expression of the genes contained in the plug-in the promoters and terminators have been replaced by functional promoters and terminators at Pichia pasteuris GS115 (Thermofischer scientific Cl 81-00)

On the plasmid pFPP56 (Table III), each promoter controlling the expression of the genes RbcX, GroES and GroEL, from CAS 19, CAS20 and CAS21 (Table II) was replaced by a compatible promoter according to the literature (Table VIII below). ). Table VIII: Expression cassettes

The region including the three expression cassettes below (Table IX) was amplified by PCR and cloned NotI into the commercial plasmid pPIC3.5 from Thermofischer K1710-01.

Table IX: expression vectors

These plasmids were previously linearized and transformed individually into a Pichia pasteuris GS115 strain (thermofischer Cl 81-00) auxotrophic for histidine according to the Easy Select protocol Pichia expression kit of Thermofischer and selected on minimal medium and glucose at 30 ° C.

Table X: Plasmids and Strains

Construction of Yarrowia lipolytica strains

Wild strain W29 (ATCC 20460, MatA) isolated from wastewater was used. On the plasmid pFPP56 (Table III), each promoter controlling the expression of the genes RbcX, GroES and GroEL, from CAS 19, CAS20 and CAS21 (Table II) was replaced by a compatible promoter according to the literature (Table XI below). below). Table XI: Expression cassettes

The region including the three above expression cassettes (TableXI) was amplified by PCR and cloned into the commercial plasmid pYLEXl.

Table XII: expression vector

These plasmids were linearized and transformed individually into a Yarrowia lipolytica strain auxotrophic for leucine according to the Yeast Transcription Kit Yeastearn Biotech protocol and selected on minimal medium and glucose at 28 ° C. (YLEX Expression Kit Yeastearn Biotech (Cat #: FYY201-1KT)).

Table XIII: Plasmids and Strains

Yarrowia lipolytica POlf (ATCC®MYA2613 ™)

Genotype: MATA ura3-302 leu2-270 xpr2-322 axp2-deltaNU49 XPR2 :: SUC2 Evaluation of the impact of chaperones was performed on a culture of strains POlf_01 and POlf_02 in synthetic medium without leucine at 28 ° C for 72H . 1.6. CHO cell construction

To ensure easy, versatile handling and a successful transfer of the "Chaperones" plug-in to all higher eukaryotic cells, a fourth-generation lentiviral transduction system was chosen. These lentiviral particles allow to transfer indifferently plug-in immortalized or transformed primary cells from different species of higher eukaryotes such as human or murine cells for example.

On the plasmid pFPP56 (Table III), each promoter controlling the expression of GroES and GroEL genes derived from CAS20 and CAS21 (Table II) was replaced by a compatible promoter according to the literature (Table XIV).

Table XIV: Expression cassettes

The region including the RbcX open reading phase and the two CAS55 and CAS56 expression cassettes below were PCR amplified and XhoI-KpnI cloned into the pLVX-Puro commercial plasmid from Clontech (Catalog No. 632164).

Table XV: expression vector The plasmids pLVX-Puro or pCB 10 were transformed using the Lenti-X packaging system (Clontech) in Lenti-X 293T cells (Clontech) according to the kit protocol. The supernatant containing the viral particles was filtered and added diluted to 1 / 5th or 1/2 on CHO cells in culture in 10cm petri dishes for a final volume of 5mL medium.

After 24 hours of transduction, the cells are washed with PBS and fresh culture medium supplemented with 2 μg / ml of puromycin is added for selection over 48 hours at 37 ° C. The cell line thus established is maintained at a concentration of 0 μg / ml of puromycin in the culture medium.

Table XVI: plasmid and strains

1.7. Methods

Culture method 1: Growth on glucose

The transformed cells are cultured at 30 ° C. in ambient air on YNB medium (yeast without nitrogen base) supplemented with ammonium sulfate 6.7 gL ^-1 , glucose 20 gL ^-1 , agar 20 gL ^-1 for the agar plates. complemented with a commercial medium CSM (MP Biomedicals) adapted to the selection markers of the plasmids used for the transformation (-ura, -leu, -trp) and in the presence of doxycycline 2μ / ιη1 The cultures are stopped by cooling to 4 ° C. one generation before the end of the exponential phase The culture is centrifuged, then spheroplasts are prepared by enzymatic digestion of the cell walls with a zymolyase-cytohelicase mixture in hypernic sorbitol medium (1.2M sorbitol) .The spheroplases are washed in medium hypertonic sorbitol in the presence of saturating concentrations of PMSF and EDTA (protease inhibitors), then broken by repeated pipetting and light sonication in isotonic medium (0.6M) sorbitol. low-speed centrifugation (1500 rpm) to remove large debris and then at medium speed (4000rpm) to recover intermediate size debris and mitochondria, the supernatant is recovered and the protein concentration is quantified by the Bradford method.

In vitro RuBisCO activity test

In vitro, 15 .mu.g of protein sample, resulting from this cell lysis, is added to the RuBP synthetic molecule (final 2mM) in a suitable buffer (50mM Tris / HCl pH 7.4, 10mM MgC12 +, 60mM sodium bicarbonate), for a volume 200μί reaction, allowing the RuBisCO complex, expressed in the yeast lysate, to catalyze the formation of molecules of phosphoglyceric acid. At varying times, the reactions are stopped by addition of HCl (12.1M) and the reaction products are analyzed by HPLC / MS to evaluate the carboxylase activity of the protein sample by assaying the phosphoglyceric acid product according to the time. Cultures in a controlled environment

The precultures were carried out on a chemically defined medium. After thawing, 1 mL of a stock tube (-80 ° C) was taken to inoculate a penicillin flask (100 mL) containing 10 mL of culture medium, incubated 18 hours at 30 ° C and 120 rpm. The precultures were carried out anaerobically (flasks previously flushed with nitrogen) and in the presence of doxycycline in order to avoid the toxicity problems observed in the presence of the PRK gene. The precultures were then washed three times (centrifugation, resuspension, vortex 15 s) with physiological water (NaCl, 9 g L ^"1 ), then the cell pellet was resuspended in culture medium without doxycycline.

These cells from the precultures were then inoculated in order to reach an initial optical density of 0.05 (ie 0.1 g L ^-1 ) .The starting volume of the cultures was 50 ml aerobically (flasks of Erlenmeyer flasks 250 mL) or anaerobic 35 mL (penicillin flasks of 100 mL).

The cultures were stopped after total glucose consumption or cessation of ethanol production. Each culture has been triplicated. Analyzes: Characterization of extracellular metabolites

Glucose, formic acid and major metabolites (ethanol, glycerol, acetic acid, succinic and pyruvic) concentrations were measured by high performance liquid chromatography (HPLC). The apparatus used was a chromatograph (Waters, Alliance 2690) equipped with an Aminex HPX 87-H ⁺ column (300 mm x 7.8 mm). Detection of the molecules was provided by a refractive index detector (Waters 2414 refractometer). The eluent was ₄ to 8 mM H ₂ SO ₄ at a flow rate of 0.5 mL min ^-1 , and the column temperature was set at 50 ° C. In anaerobiosis, this analysis was performed on a single flask. In this case, the calculation of the standard deviation was performed on the loss of mass and then applied to the metabolites. .

2 y

EXAMPLE 2 Effect of the chaperone combination on the reconstruction of the RuBisCO type I carboxylase activity in yeast.

The Calvin cycle allows plants and cyanobacteria to make glucose from carbon dioxide. The critical step is the fixation of CO2 on ribulose-1,5-bisphosphate (RuBP), a molecule with 5 carbons. This step requires an enzyme called RuBisCO (for Ribulose-1, 5-Biphosphate Carboxylase / Oxygenase). This enzyme allows the formation of an unstable molecule with 6 carbons which rapidly gives two molecules of 3-phosphoglycerate with 3 carbons. There are several forms of RuBisCO. Form I consists of two types of subunits: large subunits (RbcL) and small subunits (RbcS), whose correct assembly also requires the intervention of at least one specific chaperone: RbcX. RuBP, substrate of RuBisCO, is formed by reaction of ribulose-5-phosphate with ATP; this reaction is catalyzed by a phosphoribulokinase (PRK).

In this example, an artificial Calvin cycle is reconstituted by the co-transformation of the yeast strain CEN.PK 1605 by the combinations of vectors No. 3 and 4 of Table IV above, which allow the simultaneous expression of the RbcS and RbcL units of RuBisCO, RbcX-specific chaperone and Synechoccocus elongatus PRK enzyme, with (combination 3 and 101) or without (combination 4) the general Groel and GroES chaperones of E. coli or synechoccocus according to the number of the combination.

Thus, RuBisCO activity tests on three independent experiments A, B and C are made from protein extracts derived from yeast culture on glucose (protocol detailed above, point 1.3); their yield is evaluated by measuring the phosphoglyceric acid production as a function of time. The results are shown in Table XVII below.

Table XVII: In vitro activity tests of RuBisCO made from extracts of CEN-PK strains grown on glucose and containing the engineering indicated in the first column. The tests are carried out for 80 min of incubation with 0.01-0.02 mg of yeast soluble extract protein in a reaction volume of 200 microL containing 2 mM ribulose diphosphate at room temperature. The activities are given in nmoles of 3-phosphoglycerate formed / min / mg of total protein in the extract. Strains A li C

CEN.PK # 3 RbcS / RbcL / RbcX / PRK / (GroES / GroEL) E.coli 20 13 20

CEN.PK # 4 RbcS / RbcL / RbcX 0 ND ND

CEN.PK

RbcS / RbcL / RbcX / PRK / (GroES / GroEL2) S.elongatus ND ND 1.5 No. 101

Experiment A demonstrates that the presence of the RbcX chaperone alone, which is specific for the RuBisCO complex, is not sufficient to allow the expression of an active enzyme complex. Only the combination of the two general GroE and GroEL chaperones of E. coli associated in a stoichiometry adapted to the presence of RbcX, makes it possible to detect the production of phosphoglyceric acid increasing in the time.

In addition, experiment C shows that the RuBisCO activity drops dramatically by more than 90% when the RbcL / RbcS subunits of Synechoccocus elongatus are associated with homologous RbcX, GroES GroEL2 chaperones from the same organism. This illustrates in a striking way the interest of an association of heterologous chaperonines.

This example makes it possible to clearly determine that the association of heterologous bacterial general chaperones with the bacterial chaperone RbcX is necessary to optimize the activity of a synthetic RuBisCO complex in yeast.

Example 3: Protective effect of the combination of chaperones against the toxicity of recombinant proteins

Effect on the release of toxicity related to the expression of ribulokinase in vivo, independently of RuBisCO

The methods and analyzes used are described in Example 1 above. The expression of ribulokinase alone in yeast (strain 18b) results in a long latency phase (of more than 50 hours) and a drastic fall in its maximum growth rate (from 70% aerobically and 82% anaerobically) relative to the wild-type strain (WT) (Table XVIII).

Table XVIII: Genotype, maximum growth rate and growth retardation of strains WT, lb, 18b, 102, 15, 14b.

PV = empty plasmid

This PRK-induced toxicity can be partially overcome by coexpression in strain 102 of GroES / GroEL chaperones of E. coli. coli (removal of 26% anaerobiosis and 42% aerobic aerobic toxicity) or RbcX chaperone from Synechococcus elongatus in strain 14b (release of 34% anaerobiosis 10% aerobic).

Coexpression in strain 15 of GroES / GroEL chaperones of E. coli. coli and RbcX Synechococcus elongatus can restore almost all growth (lifting the toxicity on the growth rate of 78% anaerobically and 63% aerobic). This coexpression also makes it possible to completely eliminate the long lag phase. The toxicity related to the expression of ribulokinase (PRK) affects the alcoholic fermentation characterized by a drop in productivity in ethanol (strain 18b) (Figure 1) directly related to the presence of latency phase and the fall in the rate of growth. The expression of "CHAPERONNES" engineering (GroES + GroEL of E.coli + RbcX from Synechococcus elongatus) not only makes it possible to completely eliminate the toxicity of ribulokinase (PRK) and more particularly to the accumulation of the product of the catalyzed reaction PRK, but also to increase the productivity of ethanol (strain 15), whereas the general-interest chaperonine pair GroES / GroEL has only a partial effect (strain 102) and the expression of RbcX alone. has none (strain 14b).

Example 4: Exemplification of the general effect on the growth of a transformed cell

4.1. General effect on the growth of Saccharomyces cerevisiae in fermentation

The methods and analyzes used are described in Example 1 above. The results are shown in Table XIX below.

Table XIX: Genotype, maximum growth rate and growth retardation of strains WT, lb, 103, 13b.

PV = empty plasmid

Interestingly, the expression "CHAPERONNES" engineering offers a 30% proliferative advantage to strain 13b (RbcX + (Gros / GroEL) E. coli) in comparison with the strain. control containing 3 "empty" plasmids (strain lb), or the strain 103 expressing only general chaperones of E. coli GroES / GroEL.

In addition, the growth rate of strain 13b is equal to 96 and 86% of the growth rate of the wild-type (WT) strain CEN.PK 113-7D which is not transformed and therefore not stressed, aerobically and anaerobically respectively (Table XVIII). ).

4.2. General effect on the growth of Pichia pastoris in fermentation

The evaluation of the impact of the chaperones was carried out on a culture of strains PPGC115_01 and PPGC115_02 minimal glycerolated medium at 30 ° C for 14H and induction with 1% methanol for 48H to 100H according to the protocol described in F. Wang et al. . 2015 (PLoS One 2015 Mar 17; 10 (3): e0120458 "High-level expression of endo-β-Ν-acetylglucosaminidase H from Streptomyces plicatus in Pichia pastoris and its application for deglycosylation of glycoproteins.").

The two strains were seeded at the same cell concentration evaluated on a 100H fermentation, the maximum mu of the strain calculated on the exponential phase of the growth curve for the strain PPGC115_02 a proliferative advantage of the order of 30% by compared to that of the control strain PPGC115_01.

4.3. General effect on the growth of Yarrowia lipolytica in fermentation

Strains POlf_01 and POlf_02 were evaluated according to the protocol described in JM Nicaud et al. 2002 (Protein expression and secretion in the Yeast Yarrowia lipolytica, FEMS Yeast Res., 2002 Aug; 2 (3): 371-9). The phenotype shows increased growth for the strain expressing the combination of chaperones. The proliferative advantage is estimated at more than 35%.

4.4. General effect on the growth of CHO cells The CHO-01 and CHO-02 lines are seeded at the same density (ie 2.10 ⁶ cells per 10 cm dish and the growth is evaluated over 4 days) The cells are detached and individualized by treatment trypsin and counted daily using a meter automatic. The growth rate of the cells of the CHO-02 line is higher than that of the CHO-01 control line of the order of 25%. The combination of chaperones has an effect on the cell doubling time.

These studies demonstrate that this "CHAPERONNES" engineering allows (i) to restore a normal growth of eukaryotic cells, containing another engineering or not, but subject to physicochemical stresses and (ii) to offer a proliferative advantage over strains / cells used under the same conditions.

Example 5: Exemplification of the Effect on the Production of Recombinant Proteins 5.1. Production of human growth hormone in Saccharomyces cerevisiae

The human growth hormone gene (GenBank: K02382.1) was synthesized and cloned downstream of the constitutive promoter TEF1 according to the cassette below.

Table XX: Expression Cassette

These plasmids were transformed together in the strain CEN.PK 1605 according to the transformation protocol previously described. The strains were selected on synthetic medium (-leu-ura). " _^

Table XXII: Strains

The strains 200, 230 and 231 were cultured in a synthetic medium (-leu-ura) up to a OD 600 of 0.7. The cells were harvested and washed once with 1 ml of cold lysis buffer (PBS IX pH 7.4, 1 mM PMSF), then resuspended in 0.3 ml of Laemli buffer and incubated for 5 min at 98 ° C. . Serial dilution (1:10) is performed and the same volume of each sample is deposited on a 4% -20% SDS gradient page gel, transferred to a nitrocellulose membrane. The expression of hGH is evaluated with the Abcam [GH-1] antibody (ab9821) and standardized with respect to the expression of the ubiquitous GAPDH gene (Ab9485) from Abcam. Moreover, the quantification of the expression of hGH is carried out by Elisa assay with and according to the protocol of the Growth Hormone kit ELISA Kit, Human Catalog number: EHGH1 from thermoscientific

The amount of hGH protein produced evaluated in strain 230 is 40% higher than that obtained in strain 211.

5.2. Evaluation of endogenous luciferase activity in Saccharomyces cerevisiae

The firefly luciferase gene was amplified from the pGL4 vector (Promega) and cloned downstream of the constitutive promoter TEF1 according to the cassette below. Table XXIII: expression cassette

Names Promoters Open Reading Phase Terminator

CAS 53 TEFlp fLuc PGK ""

Table XXIV: expression vectors

These plasmids were transformed together in the strain CEN.PK 1605 according to the transformation protocol previously described. The strains were selected on synthetic medium (-leu-ura).

Table XXV: plasmids and strains

The strains 200, 210 and 211 were cultured in a synthetic medium (-leu-ura) up to a OD 600 of 0.7. The cells were harvested and washed once with 1 ml of cold lysis buffer (pH 7.4 PBS, 1 mM PMSF), and resuspended in 0.3 ml of the same buffer.

The cells in suspension were lysed with glass beads (fast prep).

The concentration of crude lysates was determined by the Bradford method (BioRad) and diluted to 0.5 mg / mL, and Luciferase activities were determined using 5 μL of lysate / sample using the Luciferase Assay System (Promega) and the luminescence evaluated on a luminometer.

The activity is standardized with respect to the amount of total protein.

The luciferase activity evaluated in strain 210 is 60% higher than that evaluated in strain 211 5.3. Evaluation of the activity of a recombinant cellulase in Saccharomyces cerevisiae

Chaperonnes engineering is associated with engineering to express Talaromyces emersonii cellulase, cellobiohydrolase 1 (CBH1) (GenBank accession No. AAL89553) under TEF2 promoter. Cellulase activity analysis was conducted as described in Y. Ito et al. 2015 (Combinatorial Screening for Transgenic Yeasts with High Cellulase Activities in Combination with a Tunable Expression System, PLoS One 2015 Dec 21; 10 (12)).

The activity recorded for the strain coexpressing Cellulase engineering in the presence of Chaperones exhibits a 37% higher activity yield than the strain expressing only Cellulase engineering alone.

5.4. Improved protein production

The use of chaperones to improve the production of proteins described above for Saccharomyces can easily be implemented in any eukaryotic cell of interest and in particular in Pichia and Yarrowia, so as to optimize the yield and / or the activity of proteins endogenous or heterogeneous. Those skilled in the art may in particular refer to the publications below to produce by yeast expressing the combination of chaperones according to the invention various proteins of interest for the food industry, the pharmaceutical field, the hydrolysis of biomass , energy, etc. :

Spohner SC, Thousand H, Quitmann H, Czermak P. Expression of enzymes for use in food and feed industry with Pichia pastoris. J Biotechnol. 2015 May 20; 202: 118-34. Kim H, Yoo SJ, Kang HA. Yeast synthetic biology for the production of recombinant therapeutic proteins. FEMS Yeast Res. 2014 Aug 12.

Ahmad M, Hirz M, Pichler H, Schwab H. Protein expression in Pichia pastoris: recent achievements and prospects for heterologous protein production. Appl Microbiol Biotechnol. 2014 Jun; 98 (12): 5301-17. doi: 10.1007 / s00253-014-5732-5. Epub 2014 Apr 18. Review.

Weinacker D, Rabert C, Zepeda AB, Figueroa CA, Pessoa A, Farias JG. Applications of Recombinant Pichia Pastoris in the Healthcare Industry. Braz J Microbiol. 2014 Mar 10; 44 (4): 1043-8

Rabert C, Weinacker D, Pessoa A Jr, Farias JG. Recombinants proteins for industrial uses: the use of Pichia pastoris expression System. Braz J Microbiol. 2013 Oct 30; 44 (2): 351-6. Spadiut O, Capone S, Krainer F, Glieder A, and Herwig C. Microbiais for the production of monoclonal antibodies and antibody fragments. Trends Biotechnol. 2014 Jan; 32 (l): 54-60.

Espejo-Mojica Â®, Almeciga-Diaz CJ, Rodriguez A, Mosquera Â, Diaz D, Beltrân L, Diaz S, Pimentel N, Moreno J, Sanchez J, Sânchez OF, Cordoba H, Poutou-Pinales RA, Barrera LA. Human recombinant lysosomal enzymes produced in microorganisms. Mol Genet Metab. 2015 Sep-Oct; 116 (1-2): 13-23.

Giindiiz Ergiin B, Çalik P. Lignocellulose degrading extremozymes produced by Pichia pastoris: current status and future prospects. Bioprocess Biosyst Eng. 2015 Oct 23. Ledesma-Amaro R, Dulermo T, Nicaud JM. Engineering Yarrowia lipolytica to produce biodiesel from raw starch. Biotechnol Biofuels. 2015 Sep 15; 8: 148.

Kalyani D, Tiwari MK, Li J, Kim SC, Kalia VC, Kang YC, Lee JK. A highly efficient recombinant laccase from the Yeast Yarrowia lipolytica and its application in the hydrolysis of biomass. PLoS One. 2015 Mar 17; 10 (3): e0120156.

Zinjarde SS. Food-related applications of Yarrowia lipolytica. Food Chem.

2014; 152: 1-10.

Hughes SR, Lopez-Nunez JC, Jones MA, Moser BR, Cox EJ, Lindquist M, Galindo Leva LA, Riano-Herrera NM, Rodriguez-Valencia N, Gast F, Cedeno DL, Tasaki K, RC Brown, Darzins A, Brunner L. Biofuels and Bioproducts Combined Biochemical and Thermochemical Processes in a Multi-Stage Biorefinery Concept. Appl Microbiol Biotechnol. 2014 Oct; 98 (20): 8413-31.

Groenewald M, Boekhout T, Neuvéglise C, Gaillardin C, van Dijck PW, Wyss Yarrowia lipolytica: safety assessment of an oleaginous yeast with a great industrial potential. Crit Rev Microbiol. 2014 Aug; 40 (3): 187-206.

Celik E, Calik P. Production of recombinant proteins by yeast cells. Biotechnol Adv. 2012 Sep-Oct; 30 (5): 1108-18.

Sabirova JS, Haddouche R, Van Bogaert I, Mulaa F, Verstraete W, Timmis K, Schmidt-Dannert C, Nicaud J, Soetaert W. The 'LipoYeasts' project: using the oleaginous yeast Yarrowia lipolytica in combination with specific bacterial genes for the bioconversion of lipids, fats and oils into high-value products. Microb Biotechnol. 2011 Jan; 4 (l): 47-54.

Claims

1) transformed eukaryotic cell, characterized in that it contains:

(i) an expression cassette containing a coding sequence for an RbcX chaperone involved in the refolding of a form I bacterially derived Rubisco enzyme, under transcriptional control of a suitable promoter;

2) eukaryotic cell according to claim 1, characterized in that the chaperone RbcX is a chaperone of cyanobacteria.

3) eukaryotic cell according to claim 1 or claim 2, characterized in that at least one of the general chaperones GroES and GroEL does not come from a cyanobacterium or other bacteria expressing RuBisCO complex.

4) A eukaryotic cell according to any one of claims 1 to 3, characterized in that the three expression cassettes form a continuous block of genetic information.

5) eukaryotic cell according to any one of claims 1 to 4, characterized in that the expression cassettes of the three chaperones are carried by a single episomal genetic element.

6) eukaryotic cell according to any one of claims 1 to 5, characterized in that it further comprises at least one expression cassette for a heterologous protein other than said chaperones, or in that it has undergone engineering sequence modifying the level of expression and / or the sequence of an endogenous protein.

7) eukaryotic cell according to any one of claims 1 to 6, characterized in that it does not contain a coding sequence for an RbcL or RbcS subunit of a RuBisCO enzyme of form I of bacterial origin. 8) Cell according to any one of claims 1 to 7, characterized in that it is a yeast, preferably selected from Saccharomyces cerevisiae, Yarrowia lipolytica and Pichia pastoris.

9) Use of a combination of expression cassettes allowing the expression of an RbcX chaperone and GroES and GroEL chaperones to improve the physiology of a eukaryotic cell.

10) Use according to claim 9 for improving the physiology of a yeast strain.

11) Use according to claim 9 or 10, for improving the physiology of a eukaryotic cell comprising at least one expression cassette for a heterologous protein other than said chaperones, or having undergone a sequence engineering that modifies the level of expression and or the sequence of an endogenous protein.

12) Use according to any one of claims 8 to 11 for increasing the growth rate of said eukaryotic cell.

13) Use according to any one of claims 8 to 12 for increasing the resistance of said eukaryotic cell to environmental stress.

14) Use according to claim 13, wherein the environmental stress is due to the toxicity of an element present in the culture medium of the eukaryotic cell.

15) Use according to any one of claims 8 to 14 for increasing the resistance of said cell to the toxicity of a compound synthesized by the eukaryotic cell. 16) Use of a eukaryotic cell according to any one of claims 1 to 8 for the production of a recombinant protein.

17) Biotechnological process for producing at least one compound selected from chemical molecules and proteins, characterized in that it comprises a step of culturing a eukaryotic cell according to any one of Claims 1 to 8 under conditions allowing the synthesis, by said eukaryotic cell, of this compound, and optionally a step of recovering said compound. 18) A process for producing a recombinant protein comprising (i) inserting a sequence encoding said protein into a eukaryotic cell expressing RbcX, GroES and GroEL, (ii) culturing said cell under conditions permitting expression of said sequence and optionally (iii) recovering or purifying said protein. 19) The method of claim 17 or 18 characterized in that said protein is an enzyme.

20) The method of claim 17 or 18 characterized in that said protein is a hormone.