WO1994021786A1 - Enzyme presentant une activite de pectine lyase - Google Patents

Enzyme presentant une activite de pectine lyase Download PDF

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WO1994021786A1
WO1994021786A1 PCT/DK1994/000105 DK9400105W WO9421786A1 WO 1994021786 A1 WO1994021786 A1 WO 1994021786A1 DK 9400105 W DK9400105 W DK 9400105W WO 9421786 A1 WO9421786 A1 WO 9421786A1
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Prior art keywords
seq
enzyme
pectin lyase
pectin
thr
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PCT/DK1994/000105
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English (en)
Inventor
Henrik DALBØGE
Lene Venke Kofod
Markus Sakari Kauppinen
Lene Nonboe Andersen
Stephan Christgau
Hans Peter Heldt-Hansen
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Novo Nordisk A/S
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Priority claimed from DK017993A external-priority patent/DK17993A/da
Priority claimed from DK121693A external-priority patent/DK121693D0/da
Application filed by Novo Nordisk A/S filed Critical Novo Nordisk A/S
Priority to EP94908995A priority Critical patent/EP0688359A1/fr
Priority to BR9406611A priority patent/BR9406611A/pt
Priority to AU62032/94A priority patent/AU677296B2/en
Priority to US08/887,365 priority patent/US5858760A/en
Publication of WO1994021786A1 publication Critical patent/WO1994021786A1/fr

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    • C—CHEMISTRY; METALLURGY
    • C12—BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
    • C12N—MICROORGANISMS OR ENZYMES; COMPOSITIONS THEREOF; PROPAGATING, PRESERVING, OR MAINTAINING MICROORGANISMS; MUTATION OR GENETIC ENGINEERING; CULTURE MEDIA
    • C12N9/00—Enzymes; Proenzymes; Compositions thereof; Processes for preparing, activating, inhibiting, separating or purifying enzymes
    • C12N9/88—Lyases (4.)
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B42/00—Surgical gloves; Finger-stalls specially adapted for surgery; Devices for handling or treatment thereof
    • A61B42/40—Packages or dispensers
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B42/00—Surgical gloves; Finger-stalls specially adapted for surgery; Devices for handling or treatment thereof
    • A61B42/50—Devices for putting-on or removing

Definitions

  • the present invention relates to an enzyme with pectin lyase activity, a method of producing the enzyme, and an enzyme preparation containing the enzyme.
  • Pectin polymers are important constituents of plant primary cell walls. They are composed of chains of 1,4-lin ed ⁇ -D- galacturonic acid and methylated derivatives thereof. The use of pectin-degrading enzymes is important for the food industry, primarily in fruit and vegetable processing such as fruit juice production or wine making, where their ability to catalyse the degradation of the backbone of the pectin polymer is utilised.
  • pectin degrading enzymes catalyses the removal of methanol from pectin, resulting in the formation of pectic acid (polygalacturonic acid) .
  • pectate lyase cleaves glycosidic bonds in polygalacturonic acid by ⁇ -elimination
  • pectin lyase cleaves the glycosidic bonds of highly methylated pectins by ⁇ - elimination
  • polygalacturonase hydrolyses the glycosidic linkages in the polygalacturonic acid chain.
  • pectin lyase may be used, alone or in combination with one or more other pectin degrading enzymes, in the production of fruit juice, in particular citrus juice, for partial or complete degradation of the pulp present in the juice after pressing.
  • each of the pectin degrading enzymes present in, for instance, commercial preparations containing a number of different pectin degrading enzymes (an example of such a preparation is Pectinex Ultra SP ® , prepared from Aspergillus aculeatus. available from Novo Nordisk A/S) in a form free from other components.
  • Pectinex Ultra SP ® prepared from Aspergillus aculeatus. available from Novo Nordisk A/S
  • enzyme preparations adapted to specific purposes, such preparations either containing a single pectin degrading enzyme or arbitrary combinations thereof.
  • the present invention relates to an enzyme exhibiting pectin lyase activity, which enzyme is immunologically reactive with an antibody raised against a purified pectin lyase derived from Aspergillus aculeatus. CBS 101.43.
  • the term "derived from” is intended not only to indicate a pectin lyase produced by strain CBS 101.43, but also a pectin lyase encoded by a DNA sequence isolated from strain CBS 101.43 and produced in a host organism transformed with said DNA sequence.
  • the invention relates to an enzyme exhibiting pectin lyase activity, which enzyme is encoded by a DNA sequence comprising at least one of the following partial sequences
  • the invention relates to an enzyme exhibiting pectin lyase activity, which enzyme is encoded by a DNA sequence comprising at least one of the following partial sequences
  • the enzyme is encoded by the DNA sequence shown in the Sequence Listing as SEQ ID NO: 35 or a sequence homologous thereto encoding a polypeptide with pectin lyase activity.
  • the term "homologue” is intended to indicate a polypeptide encoded by a DNA sequence which is at least 75% homologous to the sequence shown above encoding the pectin lyase of the invention, such as at least 80%, at least 85% at least 90% or even at least 95% homologous to any of the sequences shown above.
  • the term is intended to include modifications of the DNA sequence shown above, such as nucleotide substitutions which do not give rise to another amino acid sequence of the pectin lyase, but which correspond to the codon usage of the host organism into which the DNA construct is introduced or nucleotide substitutions which do give rise to a different amino acid sequence and therefore, possibly, a different protein structure which might give rise to a pectin lyase mutant with different properties than the native enzyme.
  • Other examples of possible modifications are insertion of one or more nucleotides into the sequence, addition of one or more nucleotides at either end of the sequence, or deletion of one or more nucleotides at either end or within the sequence.
  • the enzyme of the invention may be isolated by a general method involving
  • cloning in suitable vectors, a DNA library from Aspergillus aculeatus. transforming suitable yeast host cells with said vectors, - culturing the host cells under suitable conditions to express any enzyme of interest encoded by a clone in the DNA library, and - screening for positive clones by determining any pectin lyase activity of the enzyme produced by such clones.
  • the DNA sequence coding for the enzyme may for instance be isolated by screening a cDNA library of Aspergillus aculeatus, e.g strain CBS 101.43, publicly available from the Centraalbureau voor Schimmelcultures, Delft, NL, and selecting for clones expressing the appropriate enzyme activity (i.e. pectin lyase activity as defined by the ability of the enzyme to cleave the glycosidic bonds of highly methylated pectin by ⁇ -elimination) .
  • the appropriate DNA sequence may then be isolated from the clone by standard procedures, e.g. as described in Example 1.
  • DNA encoding a homologous enzyme may be isolated by similarly screening a cDNA library of another microorganism, in particular a fungus, such as a strain of an Aspergillus sp. , in particular a strain of A. aculeatus or A. niger, a strain of a Trichoderma sp. , in particular a strain of T. harzianu or T. reesie. a strain of a Fusarium sp., in particular a strain of F ⁇ oxysporum. or a strain of a Humicola sp.
  • a fungus such as a strain of an Aspergillus sp. , in particular a strain of A. aculeatus or A. niger, a strain of a Trichoderma sp. , in particular a strain of T. harzianu or T. reesie. a strain of a Fusarium sp., in particular a strain of F ⁇
  • the DNA coding for a pectin lyase of the invention may, in accordance with well-known procedures, conveniently be isolated from DNA from any of the above mentioned organisms by use of synthetic oligonucleotide probes, prepared on the basis of a DNA sequence disclosed herein.
  • a suitable oligonucleotide probe may be prepared on the basis of any of the partial nucleotide sequences (a)-(ee) listed above (cf. Sambrook et al., Molecular Cloning. A Laboratory Manual, Cold Spring Harbor, NY, 1989) .
  • the DNA sequence may subsequently be inserted into a recombinant expression vector.
  • This may be any vector which may conveniently be subjected to recombinant DNA procedures, and the choice of vector will often depend on the host cell into which it is to be introduced.
  • the vector may be an autonomously replicating vector, i.e. a vector which exists a ⁇ an extrachromosomal entity, the replication of which is independent of chromosomal replication, e.g. a plasmid.
  • the vector may be one which, when introduced into a host cell, is integrated into the host cell genome and replicated together with the chromosome(s) into which it has been integrated.
  • the DNA sequence encoding the pectin lyase should be operably connected to a suitable promoter and terminator sequence.
  • the promoter may be any DNA sequence which shows transcriptional activity in the host cell of choice and may be derived from genes encoding proteins either homologous or heterologous to the host cell.
  • the procedures used to ligate the DNA sequences coding for the pectin lyase, the promoter and the terminator, respectively, and to insert them into suitable vectors are well known to persons skilled in the art (cf. , for instance, Sambrook et al., Molecular Cloning. A Laboratory Manual, Cold Spring Harbor, NY, 1989) .
  • the host cell which is transformed with the DNA sequence encoding the enzyme of the invention is preferably a eukaryotic cell, in particular a fungal cell such as a yeast or filamentous fungal cell.
  • the cell may belong to a species of Aspergillus. most preferably Aspergillus orvzae or Aspergillus niger.
  • Fungal cells may be transformed by a process involving protoplast formation and transformation of the protoplasts followed by regeneration of the cell wall in a manner known per se.
  • Aspergillus as a host microorganism is described in EP 238 023 (of Novo Nordisk A/S) , the contents of which are hereby incorporated by reference.
  • the host cell may also be a yeast cell, e.g. a strain of Saccharomyces. in particular Saccharo yces cerevisiae.
  • the present invention relates to a method of producing an enzyme according to the invention, wherein a suitable host cell transformed with a DNA sequence encoding the enzyme is cultured under conditions permitting the production of the enzyme, and the resulting enzyme is recovered from the culture.
  • the medium used to culture the transformed host cells may be any conventional medium suitable for growing the host cells in question.
  • the expressed pectin lyase may conveniently be secreted into the culture medium and may be recovered therefrom by well-known procedures including separating the cells from the medium by centrifugation or filtration, precipitating proteinaceous components of the medium by means of a salt such as ammonium sulphate, followed by chromatographic procedures such as ion exchange chromatography, affinity chromatography, or the like.
  • the thus purified pectin lyase may be employed for immunization of animals for the production of antibodies. More specifically, antiserum against the pectin lyase of the invention may be raised by immunizing rabbits (or other rodents) according to the procedure described by N. Axelsen et al. in: A Manual of Quantitative Im ⁇ tunoelectrophoresis, Blackwell Scientific Publications, 1973, Chapter 23, or A. Johnstone and R. Thorpe, Immunochemistrv in Practice. Blackwell Scientific Publications, 1982 (more specifically pp. 27-31) .
  • Purified immunoglobulins may be obtained from the antisera, for example by salt precipitation ((NH 4 ) 2 S0 4 ) , followed by dialysis and ion exchange chromatography, e.g. on DEAE-Sephadex.
  • Immunochemical characterization of proteins may be done either by Outcherlony double-diffusion analysis (O. Outcherlony in: Handbook of Experimental Immunology (D.M. Weir, Ed.), Blackwell Scientific Publications, 1967, pp. 655-706), by crossed immunoelectrophoresis (N. Axelsen et al.. supra, Chapters 3 and 4) , or by rocket immunoelectrophoresis (N. Axelsen et al.. Chapter 2,) .
  • the present invention relates to an enzyme preparation useful for the degradation of plant cell wall components, said preparation being enriched in an enzyme exhibiting pectin lyase activity as described above.
  • the enzyme preparation according to the invention is preferably used as an agent for degradation or modification of plant cell walls.
  • degradation of plant cell walls is the most preferred use of the pectin lyase according to the invention, due to the high plant cell wall degradation activity.
  • the enzyme preparation may also comprise one or more other enzymes capable of degrading plant cell wall components, such as a pectate lyase, galactanase, pectin methylesterase, xylanase, glucanase, arabinanase, pectin acetylesterase, rhamnogalacturonase, polygalacturonase or polygalacturonase.
  • enzymes capable of degrading plant cell wall components, such as a pectate lyase, galactanase, pectin methylesterase, xylanase, glucanase, arabinanase, pectin acetylesterase, rhamnogalacturonase, polygalacturonase or polygalacturonase.
  • Fig. 1 shows the plasmid pYHD17
  • Fig. 2 shows the plasmid pHD414
  • Fig. 3 is a graph showing the pectin lyase activity of a number of different Aspergillus orvzae transformants
  • Fig. 4a shows the molecular weight of the pectin lyase, when analyzed on a silver-stained SDS-PAGE gel
  • Fig. 4b shows the pi of the pectin lyase when analyzed on a Coomasie stained IEF gel
  • Fig. 5 is a graph showing the relative activity of the pectin lyase
  • Fig. 6 is a graph showing the pH stability of the pectin lyase
  • Fig. 7 is a graph showing the temperature optimum of the pectin lyase
  • Fig. 8 is a graph showing the temperature stability of the pectin lyase.
  • Fig. 9 is a graph showing the K,,, and V ⁇ of the pectin lyase.
  • Donor organism mRNA was isolated from Aspergillus aculeatus. CBS 101.43, grown in a soy-containing fermentation medium with agitation to ensure sufficient aeration.Mycelia were harvested after 3-5 days* growth, immediately frozen in liquid nitrogen and stored at -80°C.
  • Yeast strains The Saccharomyces cerevisiae strain used was yNG231 (MAT alpha, leu2, ura3-52, his4-539, pep4-delta 1, cir+) or JG169 (MAT ; ura 3-52; leu 2-3, 112; his 3-D200; pep 4-113; prcl::HIS3; prbl:: LEU2 ; cir+) .
  • Plasmid Construction of an expression plasmid The commercially available plasmid pYES II (Invitrogen) was cut with Spel, filled in with Klenow DNA polymerase + dNTP and cut with Clal. The DNA was size fractionated on an agarose gel, and a fragment of about 2000 bp was purified by electroelution. The same plasmid was cut with Clal/PvuII, and a fragment of about 3400 bp was purified by electroelution. The two fragments were ligated to a blunt-ended Sphl/EcoRI fragment containing the yeast TPI promoter. This fragment was isolated from a plasmid in which the TPI promoter from S_;_ cerevisiae (cf. T.
  • RNA extraction buffer (4 M GuSCN, 0.5% Na-laurylsarcosine, 25 mM Na-citrate, pH 7.0, 0.1 M ⁇ -mercaptoethanol) . The mixture was stirred for 30 min.
  • RNA pellet was transferred into an Eppendorf tube, suspended in 500 ⁇ l TE, pH 7.6 (if difficult, heat occasionally for 5 min at 65°C) , phenol extracted and precipitated with ethanol for 12 h at - 20 °C (2.5 vols EtOH, 0.1 vol 3M NaAc, pH 5.2). The RNA was collected by centrifugation, washed in 70% EtOH, and resuspended in a minimum volume of DEPC-DIW. The RNA concentration was determined by measuring OD 260/280 .
  • poly(A) + RNAs were isolated by oligo(dT)-cellulose affinity chromatography (Aviv & Leder, 1972). Typically, 0.2 g of oligo(dT) cellulose (Boehringer Mannheim) was preswollen in 10 ml of 1 x column loading buffer (20 mM Tris-Cl, pH 7.6, 0.5 M NaCl, 1 mM EDTA, 0.1% SDS) , loaded onto a DEPC-treated, plugged plastic column (Poly Prep Chromatography Column, Bio Rad) , and equilibrated with 20 ml 1 x loading buffer.
  • 1 x column loading buffer (20 mM Tris-Cl, pH 7.6, 0.5 M NaCl, 1 mM EDTA, 0.1% SDS
  • RNA sample was heated at 65°C for 8 min., quenched on ice for 5 min, and after addition of 1 vol 2 x column loading buffer to the RNA sample loaded onto the column.
  • the eluate was collected and reloaded 2-3 times by heating the sample as above and quenching on ice prior to each loading.
  • the oligo(dT) column was washed with 10 vols of 1 x loading buffer, then with 3 vols of medium salt buffer (20 mM Tris-Cl, pH 7.6, 0.1 M NaCl, 1 mM EDTA, 0.1% SDS), followed by elution of the poly(A) + RNA with 3 vols of elution buffer (10 mM Tris-Cl, pH 7.6, 1 mM EDTA, 0.05% SDS) preheated to + 65°C, by collecting 500 ⁇ l fractions. The OD 260 was read for each collected fraction, and the mRNA containing fractions were pooled and ethanol precipitated at - 20°C for 12 h.
  • the poly(A) + RNA was collected by centrifugation, resuspended in DEPC-DIW and stored in 5-10 ⁇ g aliquots at - 80°C.
  • Double-stranded cDNA was synthesized from 5 ⁇ g of A. aculeatus poly(A) + RNA by the RNase H method (Gubler & Hoffman 1983, Sambrook et al., 1989) using the hair ⁇ pin modification.
  • the poly(A) + RNA (5 ⁇ g in 5 ⁇ l of DEPC-treated water) was heated at 70°C for 8 min., quenched on ice, and combined in a final volume of 50 ⁇ l with reverse transcriptase buffer (50 mM Tris-Cl, pH 8.3, 75 mM KCl, 3 mM MgC12, 10 mM DTT, Bethesda Research Laboratories) containing 1 mM each dNTP (Pharmacia) , 40 units of human placental ribonuclease inhibitor (RNasin, Promega) , 10 ⁇ g of oligo(dT) 12 . 18 primer (Pharmacia) and 1000 units of Superscript II RNase H- reverse transcriptase (Bethesda Research Laboratories) . First-strand cDNA was synthesized by incubating the reaction mixture at 45°C for 1 h.
  • reverse transcriptase buffer 50 mM Tris-Cl, pH 8.
  • Second strand synthesis After synthesis 30 ⁇ l of 10 mM Tris- Cl, pH 7.5, 1 mM EDTA was added, and the mRNA:cDNA hybrids were ethanol precipitated for 12 h at - 20°C by addition of 40 ⁇ g glycogen carrier (Boehringer Mannheim) 0.2 vols 10 M NH 4 Ac and 2.5 vols 96% EtOH.
  • 40 ⁇ g glycogen carrier Boehringer Mannheim
  • Second strand cDNA synthesis was performed by incubating the reaction tube at 16°C for 3 h, and the reaction was stopped by addition of EDTA to 20 mM final concentration followed by phenol extraction.
  • Mung bean nuclease treatment The double-stranded (ds) cDNA was ethanol precipitated at - 20°C for 12 h by addition of 2 vols of 96% EtOH, 0.1 vol 3 M NaAc, pH 5.2, recovered by centrifugation, washed in 70% EtOH, dried (SpeedVac) , and resuspended in 30 ⁇ l of Mung bean nuclease buffer (30 mM NaAc, pH 4.6, 300 mM NaCl, 1 mM ZnS04 , 0.35 mM DTT, 2% glycerol) containing 36 units of Mung bean nuclease (Bethesda Research Laboratories) .
  • the single-stranded hair-pin DNA was clipped by incubating the reaction at 30°C for 30 min, followed by addition of 70 ⁇ l 10 mM Tris-Cl, pH 7.5, 1 mM EDTA, phenol extraction, and ethanol precipitation with 2 vols of 96% EtOH and 0.1 vol 3M NaAc, pH 5.2 at - 20°C for 12 h.
  • T4 DNA polymerase The ds cDNA was blunt- ended with T4 DNA polymerase in 50 ⁇ l of T4 DNA polymerase buffer (20 mM Tris-acetate, pH 7.9, 10 mM MgAc, 50 mM KAc, 1 mM DTT) containing 0.5 mM each dNTP and 7.5 units of T4 DNA polymerase (Invitrogen) by incubating the reaction mixture at + 37°C for 15 min. The reaction was stopped by addition of EDTA to 20 mM final concentration, followed by phenol extraction and ethanol precipitation.
  • T4 DNA polymerase buffer 20 mM Tris-acetate, pH 7.9, 10 mM MgAc, 50 mM KAc, 1 mM DTT
  • Adaptor ligation and size selection After the fill-in reaction the cDNA was ligated to non-palindromic BstX I adaptors (1 ⁇ g/ ⁇ l, Invitrogen) in 30 ⁇ l of ligation buffer (50 mM Tris-Cl, pH 7.8, 10 mM MgC12, 10 mM DTT, 1 mM ATP, 25 ⁇ g/ml bovine serum albumin) containing 600 pmol BstX I adaptors and 5 units of T4 ligase (Invitrogen) by incubating the reaction mix at + 16°C for 12 h.
  • ligation buffer 50 mM Tris-Cl, pH 7.8, 10 mM MgC12, 10 mM DTT, 1 mM ATP, 25 ⁇ g/ml bovine serum albumin
  • the reaction was stopped by heating at + 70°C for 5 min, and the adapted cDNA was size-fractionated by agarose gel electrophoresis (0.8% HSB-agarose, FMC) to separate unligated adaptors and small cDNAs.
  • the cDNA was size-selected with a cut-off at 0.7 kb, and the cDNA was electroeluted from the agarose gel in 10 mM Tris-Cl, pH 7.5, 1 mM EDTA for 1 h at 100 volts, phenol extracted and ethanol precipitated at - 20°C for 12 h as above.
  • a large-scale ligation was set up in 40 ⁇ l of ligation buffer containing 9 units of T4 ligase, and the reaction was incubated at + 16°C for 12 h.
  • the ligation reaction was stopped by heating at 70°C for 5 min, ethanol precipitated at - 20°C for 12 h, recovered by centrifugation and resuspended in 10 ⁇ l DIW.
  • One ⁇ l aliquots were transformed into electrocompetent E. coli 1061 cells using the same electroporation conditions as above, and the transformed cells were titered and the library plated on LB + ampicillin plates with 5000-7000 c.f.u./plate. To each plate was added 3 ml of medium.
  • the bacteria were scraped off, 1 ml glycerol was added and stored at -80°C as pools. The remaining 2 ml were used for DNA isolation. If the amount of DNA was insufficient to give the required number of yeast transformants, large scale DNA was prepared from 500 ml medium (TB) inoculated with 50 ⁇ l of -80°C bacterial stock propagated overnight.
  • TB medium
  • yeast transformants To ensure that all the bacterial clones were tested in yeast, a number of yeast transformants 5 times larger than the number of bacterial clones in the original pools was set as the limit.
  • One ⁇ l aliquots of purified plasmid DNA (100 ng/ ⁇ l) from individual pools were electroporated (200 ⁇ , 1.5 kV, 25 ⁇ F) into 40 ⁇ l competent S. cerevisiae JG 169 cells (OD600 1.5 in 500 ml YPD, washed twice in cold DIW, once in cold 1 M sorbitol, resuspended in 0.5 ml 1 M sorbitol, Becker & Guarante, 1991) .
  • the vector pHD414 is a derivative of the plasmid p775 (described in EP 238 023) .
  • pHD 414 has a string of unique restriction sites between the promoter and the terminator.
  • the plasmid was constructed by removal of an approximately 200 bp long fragment (containing undesirable RE sites) at the 3'end of the terminator, and subsequent removal of an approximately 250 bp long fragment at the 5'end of the promoter, also containing undesirable sites.
  • the 200 bp region was removed by cleavage with Narl (positioned in the pUC vector) and Xbal (just 3' to the terminator), subsequent filling in the generated ends with Klenow DNA polymerase +dNTP, purification of the vector fragment on gel and religation of the vector fragment.
  • This plasmid was called pHD413.
  • pHD413 was cut with Stul (positioned in the 5'end of the promoter) and PvuII (in the pUC vector) , fractionated on gel and religated.
  • the plasmid pHD 414 is shown in Fig. 2.
  • YPD 10 g yeast extract, 20 g peptone, H 2 0 to 810 ml. Autoclaved, 90 ml 20% glucose (sterile filtered) added.
  • SC-URA 90 ml 10 x Basal salt, 22.5 ml 20% casamino acids, 9 ml 1% tryptophan, H 2 0 ad 806 ml, autoclaved, 3.6 ml 5% threonine and 90 ml 20% glucose or 20% galactose added.
  • SC-H broth 7.5 g/1 yeast nitrogen base without amino acids, 11.3 g/1 succinic acid, 6.8 g/1 NaOH, 5.6 g/1 casamino acids without vitamins, 0.1 g/1 tryptophan.
  • SC-H agar 7.5 g/1 yeast nitrogen base without amino acids, 11.3 g/1 succinic acid, 6.8 g/1 NaOH, 5.6 g/1 casamino acids without vitamins, 0.1 g/1 tryptophan, and 20 g/1 agar (Bacto) .
  • YNB-l agar 3.3 g/1 KH 2 P0 4 , 16.7 g/1 agar, pH adjusted to 7. Autoclaved for 20 min. at 121°C. After autoclaving, 25 ml of a 13.6% yeast nitrogen base without amino acids, 25 ml of a 40% glucose solution, 1.5 ml of a 1% L-leucine solution and 1.5 ml of a 1% histidine solution were added per 450 ml agar.
  • YNB-l broth Composition as YNB-l agar, but without the agar.
  • Pectin overlayer gel 1% agarose, 1% pectin (DE 35%) in a buffer with an appropriate pH. The gel was boiled and then cooled to 55°C before the overlayer was poured onto agar plates.
  • SDS-PAGE electrophoresis was performed in a Mini-Leak 4 electrophoresis unit (Kem-En-Tec, Copenhagen) as a modified version of the Laemli procedure [Laemmli, 1970; Christgau, 1991]. Briefly, the separation gel was cast with 12% acrylamide; 0.2% BIS acrylamide; 0.1% SDS; 0.375 M Tris pH 8.8; 0.04% APS (ammonium-persulphate) & 0.04% TEMED.
  • the stacking gel was cast with 4.5% w/w Acrylamide; 0.075% BIS-acrylamide; 0.1% SDS; 66.5 mM Tris pH 6.8; 0.4% w/w APS (ammonium persulphate) & 0.4% TEMED.
  • the electrode chambers are filled with running buffer : 25 mM Tris-base; 0.192 M glycine & 0.05% SDS, whereafter the samples containing sample buffer are loaded, and the gel is run at 2-4 mA/gel for over-night running and 10-30 mA/gel for fast running. The gel is subsequently removed and stained by either commassie or silver staining.
  • Isoelectric focusing is carried out on Ampholine PAG plates pH 3.5-9.5 (Pharmacia, Upsala) on a Multiphor electrophoresis unit according to the manufactures instructions. After electrophoresis the gel is either commassie stained or silver stained.
  • the gel is dipped in developer: 0.015% formaldehyde; 2% w/v Na 2 C0 3 for 30-60 sec. Then the gel is incubated in a second round of developer until satisfactory staining of the proteins has been achieved (5-15 min.). Finally the gel is incubated in preserving solution: 5% v/v acetic acid; 10% v/v ethanol; 5% v/v glycerol and air dried between two sheets of cellophane membrane.
  • Standard characterization For standard characterization of the enzyme, incubations are carried out in Eppendorf tubes comprising 1 ml of substrate.
  • the substrate is 75%DE pectin (purified from apple pectin manufactured by Herbstreith KG Pektin Fabrik) .
  • enzyme incubation is carried out at 30°C and the enzyme is inactivated at 95°C for 20 minutes. Enzyme incubations are carried out in triplicate. A blank is produced in which enzyme is added but inactivated immediately.
  • the enzyme activity is determined by measuring the increase in OD at 235 nm during the 15 minutes of incubation compared to the blank.
  • the OD at 235 reflects the amount of unsaturated galacturonic acid produced due to the action of pectin lyase.
  • the extinction coefficient for unsaturated galacturonic acid is
  • pH optimum is measured in 0.1 M citric acid/tri sodium phosphate buffers of varying pH.
  • pH stability is measured by leaving the enzyme for 1 hour in 0.1 M citric acid/tri sodium phosphate buffers of varying pH before the enzyme is used for incubation at pH 6.0.
  • Temperature optimum is measured by incubating the enzyme at varying temperatures for 15 minutes.
  • Temperature stability is measured by leaving the enzyme at various temperatures for 1 and 2 hours before incubation at 30°C.
  • Substrate stabilisation is measured by leaving the enzyme in the presence of substrate for 1 hour at a suitable temperature before incubation at 30°C.
  • HPLC-SEC Enzyme incubations for HPLC-SEC analyses are carried out by adding 0.18 ⁇ g of enzyme to 1 ml of 1% pectic substrate in 0.1 M acetate buffer pH 6.0 and incubate 0, 1, 2, 4 and 24 hours before the enzyme is inactivated. 25 ⁇ l of each sample is injected to the SEC columns (three TSK-gel columns connected in a row) and eluted with 0.4 M acetate buffer pH 3.0 at 0.8 ml/min supplied by a Dionex pump. Eluting carbohydrates are detected by a refractive index detector (Shimadzu) and the chromatograms are processed by Dionex software.
  • the SEC degradation profile of pectin lyase has been obtained for four different substrates: polygalacturonic acid (Sigma) , 35%DE apple pectin purified from apple pectin manufactured by Obipektin AG, 75%DE apple pectin, and Modified Hairy Regions (MHR) obtained from apples by the procedure described by Schols et al, 1990. Dextrans are used as molecular weight standards.
  • DNA was isolated from 20 individual clones from the library and subjected to analysis for cDNA insertion.
  • the insertion frequency was found to be >90% and the average insert size was approximately 1400bp.
  • DNA from some of the pools was transformed into yeast, and 50- 100 plates containing 200-500 yeast colonies were obtained from each pool. After 3-5 days of growth, the agar plates were replica plated onto several sets of agar plates. One set of plates was then incubated for 2-4 days at 30°C and overlayered with a pectin overlayer gel for detection of pectinolytic activity. Pectin lyase positive colonies were identified as colonies surrounded by a clearing zone.
  • the positive clones were obtained as single colonies, the cDNA inserts were amplified directly from the yeast colony using biotinylated polylinker primers, purified by magnetic beads (Dynabead M-280, Dynal) system and characterized individually by sequencing the 5' -end of each cDNA clone using the chain-termination method (Sanger et al., 1977) and the Sequenase system (United States Biochemical) .
  • the DNA sequence of the enzyme gene is shovn in claim 3.
  • pectin lyase-producing colonies was inoculated into 20 ml YNB-l broth in a 50 ml glass test tube. The tube was shaken for 2 days at 30°C. The cells were harvested by centrifugation for 10 min. at 3000 rpm.
  • the cells were resuspended in 1 ml 0.9 M sorbitol, 0.1 M EDTA, pH 7.5. The pellet was transferred to an Eppendorf tube, and spun for 30 seconds at full speed. The cells were resuspended in 0.4 ml 0.9 M sorbitol, 0.1 M EDTA, 14 mM /3-mercaptoethanol. 100 ⁇ l 2 mg/ml Zymolase was added, and the suspension was incubated at 37°C for 30 minutes and spun for 30 seconds. The pellet (spheroplasts) was resuspended in 0.4 ml TE.
  • the DNA was transformed into E.coli. by standard procedures. Two E ⁇ _ coli colonies were isolated from each of the transformations and analysed with the restriction enzymes Hindlll and Xbal which excised the DNA insert. DNA from one of these clones was retransformed into yeast strain JG169.
  • the DNA sequences of several of the positive clones were partially determined.
  • the partial DNA sequence of the pectin lyase of the invention is shown in claim 3.
  • the full DNA sequence and derived amino acid sequence of the pectin lyase is shown in the Sequence Listing as SEQ ID NO: 35 and SEQ ID NO: 36.
  • cDNA is isolated from one or more representatives of each family by digestion with Hindlll/Xbal or other appropriate restriction enzymes, size fractionation on a gel and purification and subsequently ligated to pHD414, resulting in the plasmid pPL-I. After amplification in E. coli, the plasmids are transformed into A. oryzae or __ niger according to the general procedure described below.
  • the suspension is cooled on ice and 1 ml of buffer containing 120 g of Novozym ® 234, batch 1687 is added. After 5 minutes 1 ml of 12 mg/ml BSA (Sigma type H25) is added and incubation with gentle agitation continued for 1.5-2.5 hours at 37°C until a large number of protoplasts is visible in a sample inspected under the microscope.
  • BSA Sigma type H25
  • protoplast suspension 100 ⁇ l of protoplast suspension is mixed with 5-25 ⁇ g of the appropriate DNA in 10 ⁇ l of STC.
  • Protoplasts are mixed with p3SR2 (an A. nidulans amdS gene carrying plasmid) .
  • the mixture is left at room temperature for 25 minutes.
  • the mixture is left at room temperature for 25 minutes, spun at 2500 g for 15 minutes and the pellet is resuspended in 2 ml of 1.2 M sorbitol.
  • Protoplasts are spread on the appropriate plates.
  • Each of the transformants 463A-2, 463A-3, 463A-6 and 463A-13 as well as the control strain 459B-1 (not transformed with a pectin lyase gene) were inoculated in YPD medium. After 5 days of incubation at 30°C, 25 ⁇ l of supernatant was added to 10 ⁇ l of 1% apple pectin (DE 75) in an appropriate buffer. The mixture was incubated at 30°C. Aliquots were taken at increasing intervals, diluted in water and measured at A 235 . The transformants exhibited a significant increase in A 235 compared to the control (cf. Fig. 3) . This demonstrates efficient expression of pectin lyase in A. oryzae.
  • the culture supernatant from fermentation of Aspergillus oryzae expressing the recombinant enzyme is centrifuged and filtered through a 0.2 ⁇ m filter to remove the mycelia.
  • 35-50 ml of the filtered supernatant is ultrafiltrated in a Filtron ultracette or Amicon ultrafiltration device with a 10 kDa membrane to achieve 10 fold concentration.
  • This concentrate is diluted 100 times in 20 mM Tris pH 8.0 in two successive rounds of ultrafiltration in the same device and the supernatant i ⁇ concentrated to a final volume of 50 ml.
  • This ultrafiltratred sample is loaded at 2 ml/min on a Pharmacia HR16/10 Fast Flow Q Sepharose anion exchanger equilibrated in 20 mM Tris pH 8.0.
  • the column is washed with two column volumes 20 mM Tris pH 8.0, and bound proteins are eluted with a linear increasing NaCl gradient from 0 to 0.6 M NaCl in 20 mM Tris pH 8.0.
  • the pectin lyase elutes at approximately 0.3-0.4 M NaCl, and fractions containing pectin lyase activity are pooled and concentrated by ultrafiltration.
  • fractions contain some Aspergillus amylase ( ⁇ -1.4- glucanase) , and in order to achieve complete purification this material is ultrafiltrated in an Amicon ultrafiltration device with a 10 kDa membrane to achieve 10 fold concentration.
  • the concentrate is diluted 100 times in 20 mM Tris pH 7.0 in two successive round of ultrafiltration in the same device.
  • the ultrafiltrated sample is loaded at 1 ml/min onto a HR5/10 Mono Q anion exchange column (Pharmacia, Uppsala) equilibrated in 20 mM Tris, pH 7.0.
  • the column is washed with two column volumes of 20 mM Tris, pH 7.0, and bound proteins are eluted with a linear increasing salt gradient from 0 to 0.4 M NaCl in Tris, pH 7.0.
  • the pectin lyase elutes at approximately 0.15 M NaCl.
  • the pectin lyase in this fraction is more than 95% pure.
  • the purified pectin lyase is subsequently characterized with respect to molecular weight, isoelectric point, pH optimum, pH stability, temperature optimum and temperature stability, substrate stabilization, buffer influence, K,,, and specific activity. Furthermore the degradation pattern of the enzyme on different pectic substrates has been investigated by HPLC Size Exclusion Chromatography.
  • Fig. 4a illustrates the result of a silver stained SDS-PAGE gel.
  • Fig. 4b illustrates the result of a Coomassie stained IEF gel.
  • the enzyme has a molecular weight of 42 kD as estimated from SDS-PAGE gels, and an isoelectric point of 3.9.
  • the pH optimum, pH stability, temperature optimum and tempera- ture stability of the purified enzyme were determined as described above and the results are apparent from Fig. 5 to 8, respectively.
  • the enzyme has a pH optimum in the range of 4.5- 8.5, exhibits an acceptable stability in the pH range 2-8 and a temperature in the range of 30-50°C, and has a temperature optimum in the range of 30-60°C.
  • the stability of the enzyme in water and in combination with substrate, respectively, was determined as described in the Materials and Methods section above.
  • the enzyme was found to by unstable in water whereas about 41% of the enzyme activity remained when the enzyme was combined with substrate.
  • Fig. 9 illustrates the plot of the substrate concentration divided by the hydrolysis velocity (S/v) as a function of the sub ⁇ trated concentration (S) used in determining K_ and the specific activity.
  • Km was determined to 0.163-0.354% 75% DE apple pectin and the specific activity to 35-50 ⁇ mol/min/mg enzyme protein.
  • the degradation pattern obtained from reaction with the purified pectin lyase was determined by a HPLC-SEC analysis performed as described in the Materials and Methods section above. It was observed that the pectin lyase does not degrade polygalacturonic acid and MHR, that 35% DE pectin is degraded to a limited extent only, and that 75% DE pectin is degraded to a large extent.
  • the limiting oligomer is a dimer indicating that a tetramer is the smallest substrate to be degraded. For 75% DE pectin a substantial amount remains as partly degraded polymeric material, which indicate that the pectin lyase requires a high degree of methyl esterification in order to act.
  • Apples were homogenized to produce a mash. After thermostating the mash to 20°C, The pectin lyase of example 3 was added in an amount of 100 g/1 and the viscosity was measured by means of a Brookfiled viscosimeter. The viscosity was reduced to 50% in 15 minutes compared to a control with no enzyme added, after which no further viscosity reduction took place. The results show that addition of single-component pectin lyase to apple mash results in a controlled, limited viscosity reduction.
  • Freshly pressed orange juice, pasteurized orange juice or orange juice rediluted from a concentrate were thermostated to 45°C, and the pectin lyase of example 3 was added to a concentration of 0.2-1.0 g/ton.
  • the viscosity and turbidity of the juice was measured by means of a Brookfield viscosimeter and Lange turbidity meter. The viscosity was reduced to 50% compared to a control with no enzyme added, whereas the turbidity was unchanged.
  • Reconcentrating the enzyme-treated juice resulted in a concentrate at 65° Brix which had a reduced viscosity compared to a sample which had not been treated with the enzyme.
  • pectin lyase treated orange juice may be concentrated to higher concentrations without gellification or to a conventional concentration (65° Brix) with a lower viscosity.
  • ORGANISM Aspergillus aculeatus
  • ORGANISM Aspergillus aculeatus
  • ORGANISM Aspergillus aculeatus
  • ORGANISM Aspergillus aculeatus
  • ORGANISM Aspergillus aculeatus
  • ORGANISM Aspergillus aculeatus
  • ORGANISM Aspergillus aculeatus
  • MOLECULE TYPE cDNA
  • HYPOTHETICAL NO
  • ANTT-SENSE NO
  • ORIGINAL SOURCE
  • ORGANISM Aspergillus aculeatus
  • ORGANISM Aspergillus aculeatus
  • ORGANISM Aspergillus aculeatus
  • ORGANISM Aspergillus aculeatus
  • ORGANISM Aspergillus aculeatus
  • ORGANISM Aspergillus aculeatus
  • xi SEQUENCE DESCRIPTION: SEQ ID NO: 15: CGCCGAIATG GICTGGATOG 20
  • ORGANISM Aspergillus aculeatus
  • ORGANISM Aspergillus aculeatus
  • ORGANISM Aspergillus aculeatus
  • ORGANISM Aspergillus aculeatus
  • ORGANISM Aspergillus aculeatus
  • ORGANISM Aspergillus aculeatus
  • ORGANISM Aspergillus aculeatus
  • ORGANISM Aspergillus aculeatus
  • ORGANISM Aspergillus aculeatus
  • ORGANISM Aspergillus aculeatus
  • ORGANISM Aspergillus aculeatus
  • ORGANISM Aspergillus aculeatus
  • ORGANISM A ⁇ pergillus aculeatus
  • ORGANISM Aspergillus aculeatus
  • MOLECULE TYPE cDNA
  • HYPOTHETICAL NO
  • ANTT-SENSE NO
  • ORGANISM Aspergillus aculeatus
  • ORGANISM Aspergillus aculeatus
  • ORGANISM Aspergillus aculeatus
  • GCC GCC CAG CTC GCC ACA GCT GTG AGT GTT TCC GGT GOG GCA GAG GGC 98 Ala Ala Gin I- u Ala Thr Ala Val Ser Val Ser Gly Ala Ala Glu Gly 15 20 25
  • GGC TOG TCC GAC CTG GTC ACC CTC CAG AAG AAT TAC ATC TAT CAC TTC 770 Gly Ser Ser Asp ⁇ -eu Val Thr Leu Gin Lys Asn Tyr He Tyr His Phe 240 245 250

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Abstract

Une enzyme, qui présente une activité de pectine lyase, réagit sur le plan immunologique avec un anticorps dirigé contre une pectine lyase purifiée provenant d'Aspergillus aculeatus, CBS 101.43. Cette enzyme se révèle utile pour dégrader des éléments de parois cellulaires végétales.
PCT/DK1994/000105 1993-02-16 1994-03-11 Enzyme presentant une activite de pectine lyase WO1994021786A1 (fr)

Priority Applications (4)

Application Number Priority Date Filing Date Title
EP94908995A EP0688359A1 (fr) 1993-02-16 1994-03-11 Enzyme presentant une activite de pectine lyase
BR9406611A BR9406611A (pt) 1993-02-16 1994-03-11 Enzima demonstrando atividade pectine liase vetor de expressão recombinante célula processo para produzir uma enzima demonstrando atividade pectina liase e preparação de enzima
AU62032/94A AU677296B2 (en) 1993-02-16 1994-03-11 An enzyme with pectin lyase activity
US08/887,365 US5858760A (en) 1993-02-16 1994-03-11 Enzyme with pectin lyase activity

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
DK017993A DK17993A (da) 1993-02-16 1993-02-16 Apparat til brug ved aftagning og påsætning af elastiske fleksible handsker
DK0279/93 1993-03-12
DK121693A DK121693D0 (fr) 1993-10-28 1993-10-28
DK1216/93 1993-10-28

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WO1994021786A1 true WO1994021786A1 (fr) 1994-09-29

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US (1) US5858760A (fr)
EP (1) EP0688359A1 (fr)
AU (1) AU677296B2 (fr)
BR (1) BR9406611A (fr)
CA (1) CA2158145A1 (fr)
WO (1) WO1994021786A1 (fr)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6419962B1 (en) * 1996-06-28 2002-07-16 Shiseido Company, Ltd. External skin treatment composition

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CA2737544A1 (fr) * 2008-09-18 2010-03-25 University Of Georgia Research Foundation, Inc. Procedes et compositions pour degrader la pectine

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0278355A2 (fr) * 1987-02-04 1988-08-17 Ciba-Geigy Ag Nouveau système d'expression
EP0353188A2 (fr) * 1988-07-28 1990-01-31 Ciba-Geigy Ag Système d'expression
EP0439997A1 (fr) * 1990-01-29 1991-08-07 Ciba-Geigy Ag Système d'expression de champignons

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5447862A (en) * 1987-02-04 1995-09-05 Ciba-Geigy Corporation Pectin lyase genes of aspergillus niger
FI83182C (fi) * 1989-12-27 1991-06-10 Kone Oy Foerfarande och anordning foer avbarkning av traed.

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0278355A2 (fr) * 1987-02-04 1988-08-17 Ciba-Geigy Ag Nouveau système d'expression
EP0353188A2 (fr) * 1988-07-28 1990-01-31 Ciba-Geigy Ag Système d'expression
EP0439997A1 (fr) * 1990-01-29 1991-08-07 Ciba-Geigy Ag Système d'expression de champignons

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6419962B1 (en) * 1996-06-28 2002-07-16 Shiseido Company, Ltd. External skin treatment composition

Also Published As

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AU6203294A (en) 1994-10-11
AU677296B2 (en) 1997-04-17
EP0688359A1 (fr) 1995-12-27
US5858760A (en) 1999-01-12
BR9406611A (pt) 1996-01-09
CA2158145A1 (fr) 1994-09-29

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