101
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Gudiminchi RK, Geier M, Glieder A, Camattari A. Screening for cytochrome P450 expression inPichia pastoriswhole cells by P450-carbon monoxide complex determination. Biotechnol J 2012; 8:146-52. [DOI: 10.1002/biot.201200185] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2012] [Revised: 07/11/2012] [Accepted: 10/15/2012] [Indexed: 12/17/2022]
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102
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Geier M, Braun A, Emmerstorfer A, Pichler H, Glieder A. Production of human cytochrome P450 2D6 drug metabolites with recombinant microbes - a comparative study. Biotechnol J 2012; 7:1346-58. [DOI: 10.1002/biot.201200187] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2012] [Revised: 07/31/2012] [Accepted: 08/24/2012] [Indexed: 01/11/2023]
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103
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104
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Harreither W, Felice AKG, Paukner R, Gorton L, Ludwig R, Sygmund C. Recombinantly produced cellobiose dehydrogenase fromCorynascus thermophilusfor glucose biosensors and biofuel cells. Biotechnol J 2012; 7:1359-66. [DOI: 10.1002/biot.201200049] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2012] [Revised: 06/05/2012] [Accepted: 07/17/2012] [Indexed: 11/10/2022]
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105
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Wallner S, Winkler A, Riedl S, Dully C, Horvath S, Gruber K, Macheroux P. Catalytic and structural role of a conserved active site histidine in berberine bridge enzyme. Biochemistry 2012; 51:6139-47. [PMID: 22757961 PMCID: PMC3413249 DOI: 10.1021/bi300411n] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
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Berberine bridge enzyme (BBE) is a paradigm for the class
of bicovalently
flavinylated oxidases, which catalyzes the oxidative cyclization of
(S)-reticuline to (S)-scoulerine.
His174 was identified as an important active site residue because
of its role in the stabilization of the reduced state of the flavin
cofactor. It is also strictly conserved in the family of BBE-like
oxidases. Here, we present a detailed biochemical and structural characterization
of a His174Ala variant supporting its importance during catalysis
and for the structural organization of the active site. Substantial
changes in all kinetic parameters and a decrease in midpoint potential
were observed for the BBE His174Ala variant protein. Moreover, the
crystal structure of the BBE His174Ala variant showed significant
structural rearrangements compared to wild-type enzyme. On the basis
of our findings, we propose that His174 is part of a hydrogen bonding
network that stabilizes the negative charge at the N1–C2=O
locus via interaction with the hydroxyl group at C2′ of the
ribityl side chain of the flavin cofactor. Hence, replacement of this
residue with alanine reduces the stabilizing effect for the transiently
formed negative charge and results in drastically decreased kinetic
parameters as well as a lower midpoint redox potential.
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Affiliation(s)
- Silvia Wallner
- Institute of Biochemistry, Graz University of Technology, Petersgasse 12/2, A-8010 Graz, Austria
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106
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Deletion of the Pichia pastoris KU70 homologue facilitates platform strain generation for gene expression and synthetic biology. PLoS One 2012; 7:e39720. [PMID: 22768112 PMCID: PMC3387205 DOI: 10.1371/journal.pone.0039720] [Citation(s) in RCA: 183] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2012] [Accepted: 05/25/2012] [Indexed: 12/16/2022] Open
Abstract
Targeted gene replacement to generate knock-outs and knock-ins is a commonly used method to study the function of unknown genes. In the methylotrophic yeast Pichia pastoris, the importance of specific gene targeting has increased since the genome sequencing projects of the most commonly used strains have been accomplished, but rapid progress in the field has been impeded by inefficient mechanisms for accurate integration. To improve gene targeting efficiency in P. pastoris, we identified and deleted the P. pastoris KU70 homologue. We observed a substantial increase in the targeting efficiency using the two commonly known and used integration loci HIS4 and ADE1, reaching over 90% targeting efficiencies with only 250-bp flanking homologous DNA. Although the ku70 deletion strain was noted to be more sensitive to UV rays than the corresponding wild-type strain, no lethality, severe growth retardation or loss of gene copy numbers could be detected during repetitive rounds of cultivation and induction of heterologous protein production. Furthermore, we demonstrated the use of the ku70 deletion strain for fast and simple screening of genes in the search of new auxotrophic markers by targeting dihydroxyacetone synthase and glycerol kinase genes. Precise knock-out strains for the well-known P. pastoris AOX1, ARG4 and HIS4 genes and a whole series of expression vectors were generated based on the wild-type platform strain, providing a broad spectrum of precise tools for both intracellular and secreted production of heterologous proteins utilizing various selection markers and integration strategies for targeted or random integration of single and multiple genes. The simplicity of targeted integration in the ku70 deletion strain will further support protein production strain generation and synthetic biology using P. pastoris strains as platform hosts.
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107
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Characterization of the two Neurospora crassa cellobiose dehydrogenases and their connection to oxidative cellulose degradation. Appl Environ Microbiol 2012; 78:6161-71. [PMID: 22729546 DOI: 10.1128/aem.01503-12] [Citation(s) in RCA: 94] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
The genome of Neurospora crassa encodes two different cellobiose dehydrogenases (CDHs) with a sequence identity of only 53%. So far, only CDH IIA, which is induced during growth on cellulose and features a C-terminal carbohydrate binding module (CBM), was detected in the secretome of N. crassa and preliminarily characterized. CDH IIB is not significantly upregulated during growth on cellulosic material and lacks a CBM. Since CDH IIB could not be identified in the secretome, both CDHs were recombinantly produced in Pichia pastoris. With the cytochrome domain-dependent one-electron acceptor cytochrome c, CDH IIA has a narrower and more acidic pH optimum than CDH IIB. Interestingly, the catalytic efficiencies of both CDHs for carbohydrates are rather similar, but CDH IIA exhibits 4- to 5-times-higher apparent catalytic constants (k(cat) and K(m) values) than CDH IIB for most tested carbohydrates. A third major difference is the 65-mV-lower redox potential of the heme b cofactor in the cytochrome domain of CDH IIA than CDH IIB. To study the interaction with a member of the glycoside hydrolase 61 family, the copper-dependent polysaccharide monooxygenase GH61-3 (NCU02916) from N. crassa was expressed in P. pastoris. A pH-dependent electron transfer from both CDHs via their cytochrome domains to GH61-3 was observed. The different properties of CDH IIA and CDH IIB and their effect on interactions with GH61-3 are discussed in regard to the proposed in vivo function of the CDH/GH61 enzyme system in oxidative cellulose hydrolysis.
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108
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Kittl R, Gonaus C, Pillei C, Haltrich D, Ludwig R. Constitutive expression of Botrytis aclada laccase in Pichia pastoris. Bioengineered 2012; 3:232-5. [PMID: 22705842 DOI: 10.4161/bioe.20037] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
The heterologous expression of laccases is important for their large-scale production and genetic engineering--a prerequisite for industrial application. Pichia pastoris is the preferred expression host for fungal laccases. The recently cloned laccase from the ascomycete Botrytis aclada (BaLac) has been efficiently expressed in P. pastoris under the control of the inducible alcohol oxidase (AOX1) promoter. In this study, we compare these results to the constitutive expression in the same organism using the glyceraldehyde-3-phosphate dehydrogenase (GAP) promoter. The results show that the amounts of BaLac produced with the GAP system (517 mgL(-1)) and the AOX1 system (495 mgL(-1)) are comparable. The constitutive expression is, however, faster, and the specific activity of BaLac in the culture supernatant is higher (41.3 Umg(-1) GAP, 14.2 Umg(-1) AOX1). In microtiter plates, the constitutive expression provides a clear advantage due to easy manipulation (simple medium, no methanol feeding) and fast enzyme production (high-throughput screening assays can already be performed after 48 h).
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Affiliation(s)
- Roman Kittl
- Food Biotechnology Laboratory, Department of Food Sciences and Technology, University of Natural Resources and Life Sciences, Vienna, Austria
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109
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Mellitzer A, Weis R, Glieder A, Flicker K. Expression of lignocellulolytic enzymes in Pichia pastoris. Microb Cell Fact 2012; 11:61. [PMID: 22583625 PMCID: PMC3503753 DOI: 10.1186/1475-2859-11-61] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2011] [Accepted: 04/21/2012] [Indexed: 12/12/2022] Open
Abstract
BACKGROUND Sustainable utilization of plant biomass as renewable source for fuels and chemical building blocks requires a complex mixture of diverse enzymes, including hydrolases which comprise the largest class of lignocellulolytic enzymes. These enzymes need to be available in large amounts at a low price to allow sustainable and economic biotechnological processes.Over the past years Pichia pastoris has become an attractive host for the cost-efficient production and engineering of heterologous (eukaryotic) proteins due to several advantages. RESULTS In this paper codon optimized genes and synthetic alcohol oxidase 1 promoter variants were used to generate Pichia pastoris strains which individually expressed cellobiohydrolase 1, cellobiohydrolase 2 and beta-mannanase from Trichoderma reesei and xylanase A from Thermomyces lanuginosus. For three of these enzymes we could develop strains capable of secreting gram quantities of enzyme per liter in fed-batch cultivations. Additionally, we compared our achieved yields of secreted enzymes and the corresponding activities to literature data. CONCLUSION In our experiments we could clearly show the importance of gene optimization and strain characterization for successfully improving secretion levels. We also present a basic guideline how to correctly interpret the interplay of promoter strength and gene dosage for a successful improvement of the secretory production of lignocellulolytic enzymes in Pichia pastoris.
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Affiliation(s)
- Andrea Mellitzer
- Institute of Molecular Biotechnology, Graz University of Technology, Graz, Austria
| | | | - Anton Glieder
- ACIB GmbH, Austrian Centre of Industrial Biotechnology, Graz, Austria
| | - Karlheinz Flicker
- ACIB GmbH, Austrian Centre of Industrial Biotechnology, Graz, Austria
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110
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Krainer FW, Dietzsch C, Hajek T, Herwig C, Spadiut O, Glieder A. Recombinant protein expression in Pichia pastoris strains with an engineered methanol utilization pathway. Microb Cell Fact 2012; 11:22. [PMID: 22330134 PMCID: PMC3295664 DOI: 10.1186/1475-2859-11-22] [Citation(s) in RCA: 132] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2011] [Accepted: 02/13/2012] [Indexed: 11/12/2022] Open
Abstract
UNLABELLED ΒACKGROUND: The methylotrophic yeast Pichia pastoris has become an important host organism for recombinant protein production and is able to use methanol as a sole carbon source. The methanol utilization pathway describes all the catalytic reactions, which happen during methanol metabolism. Despite the importance of certain key enzymes in this pathway, so far very little is known about possible effects of overexpressing either of these key enzymes on the overall energetic behavior, the productivity and the substrate uptake rate in P. pastoris strains. RESULTS A fast and easy-to-do approach based on batch cultivations with methanol pulses was used to characterize different P. pastoris strains. A strain with MutS phenotype was found to be superior over a strain with Mut+ phenotype in both the volumetric productivity and the efficiency in expressing recombinant horseradish peroxidase C1A. Consequently, either of the enzymes dihydroxyacetone synthase, transketolase or formaldehyde dehydrogenase, which play key roles in the methanol utilization pathway, was co-overexpressed in MutS strains harboring either of the reporter enzymes horseradish peroxidase or Candida antarctica lipase B. Although the co-overexpression of these enzymes did not change the stoichiometric yields of the recombinant MutS strains, significant changes in the specific growth rate, the specific substrate uptake rate and the specific productivity were observed. Co-overexpression of dihydroxyacetone synthase yielded a 2- to 3-fold more efficient conversion of the substrate methanol into product, but also resulted in a reduced volumetric productivity. Co-overexpression of formaldehyde dehydrogenase resulted in a 2-fold more efficient conversion of the substrate into product and at least similar volumetric productivities compared to strains without an engineered methanol utilization pathway, and thus turned out to be a valuable strategy to improve recombinant protein production. CONCLUSIONS Co-overexpressing enzymes of the methanol utilization pathway significantly affected the specific growth rate, the methanol uptake and the specific productivity of recombinant P. pastoris MutS strains. A recently developed methodology to determine strain specific parameters based on dynamic batch cultivations proved to be a valuable tool for fast strain characterization and thus early process development.
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Affiliation(s)
- Florian W Krainer
- Graz University of Technology, Institute of Molecular Biotechnology, Graz, Austria
| | - Christian Dietzsch
- Oliver Spadiut, Vienna University of Technology, Institute of Chemical Engineering, Research Area Biochemical Engineering, Gumpendorfer Strasse 1a, A-1060 Vienna, Austria
| | - Tanja Hajek
- Graz University of Technology, Institute of Molecular Biotechnology, Graz, Austria
| | - Christoph Herwig
- Oliver Spadiut, Vienna University of Technology, Institute of Chemical Engineering, Research Area Biochemical Engineering, Gumpendorfer Strasse 1a, A-1060 Vienna, Austria
| | - Oliver Spadiut
- Oliver Spadiut, Vienna University of Technology, Institute of Chemical Engineering, Research Area Biochemical Engineering, Gumpendorfer Strasse 1a, A-1060 Vienna, Austria
| | - Anton Glieder
- Austrian Centre of Industrial Biotechnology (ACIB GmbH), Graz, Austria
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111
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Sygmund C, Gutmann A, Krondorfer I, Kujawa M, Glieder A, Pscheidt B, Haltrich D, Peterbauer C, Kittl R. Simple and efficient expression of Agaricus meleagris pyranose dehydrogenase in Pichia pastoris. Appl Microbiol Biotechnol 2011; 94:695-704. [PMID: 22080342 PMCID: PMC3315643 DOI: 10.1007/s00253-011-3667-7] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2011] [Revised: 09/24/2011] [Accepted: 10/22/2011] [Indexed: 11/26/2022]
Abstract
Pyranose dehydrogenase (PDH) is a fungal flavin-dependent sugar oxidoreductase that is highly interesting for applications in organic synthesis or electrochemistry. The low expression levels of the filamentous fungus Agaricus meleagris as well as the demand for engineered PDH make heterologous expression necessary. Recently, Aspergillus species were described to efficiently secrete recombinant PDH. Here, we evaluate recombinant protein production with expression hosts more suitable for genetic engineering. Expression in Escherichia coli resulted in no soluble or active PDH. Heterologous expression in the methylotrophic yeast Pichia pastoris was investigated using two different signal sequences as well as a codon-optimized sequence. A 96-well plate activity screening for transformants of all constructs was established and the best expressing clone was used for large-scale production in 50-L scale, which gave a volumetric yield of 223 mg L−1 PDH or 1,330 U L−1 d−1 in space–time yield. Purification yielded 13.4 g of pure enzyme representing 95.8% of the initial activity. The hyperglycosylated recombinant enzyme had a 20% lower specific activity than the native enzyme; however, the kinetic properties were essentially identical. This study demonstrates the successful expression of PDH in the eukaryotic host organism P. pastoris paving the way for protein engineering. Additionally, the feasibility of large-scale production of the enzyme with this expression system together with a simplified purification scheme for easy high-yield purification is shown.
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Affiliation(s)
- Christoph Sygmund
- Department of Food Sciences and Technology, University of Natural Resources and Applied Life Sciences (BOKU), Muthgasse 11, 1190 Vienna, Austria
| | - Alexander Gutmann
- Austrian Centre of Industrial Biotechnology (ACIB), Petersgasse 14, 8010 Graz, Austria
| | - Iris Krondorfer
- Department of Food Sciences and Technology, University of Natural Resources and Applied Life Sciences (BOKU), Muthgasse 11, 1190 Vienna, Austria
| | - Magdalena Kujawa
- Department of Food Sciences and Technology, University of Natural Resources and Applied Life Sciences (BOKU), Muthgasse 11, 1190 Vienna, Austria
- Austrian Centre of Industrial Biotechnology (ACIB), Petersgasse 14, 8010 Graz, Austria
| | - Anton Glieder
- Austrian Centre of Industrial Biotechnology (ACIB), Petersgasse 14, 8010 Graz, Austria
| | - Beate Pscheidt
- Austrian Centre of Industrial Biotechnology (ACIB), Petersgasse 14, 8010 Graz, Austria
| | - Dietmar Haltrich
- Department of Food Sciences and Technology, University of Natural Resources and Applied Life Sciences (BOKU), Muthgasse 11, 1190 Vienna, Austria
| | - Clemens Peterbauer
- Department of Food Sciences and Technology, University of Natural Resources and Applied Life Sciences (BOKU), Muthgasse 11, 1190 Vienna, Austria
| | - Roman Kittl
- Department of Food Sciences and Technology, University of Natural Resources and Applied Life Sciences (BOKU), Muthgasse 11, 1190 Vienna, Austria
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112
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Mellitzer A, Glieder A, Weis R, Reisinger C, Flicker K. Sensitive high-throughput screening for the detection of reducing sugars. Biotechnol J 2011; 7:155-62. [DOI: 10.1002/biot.201100001] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2011] [Revised: 02/04/2011] [Accepted: 02/20/2011] [Indexed: 11/09/2022]
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113
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Qin X, Qian J, Xiao C, Zhuang Y, Zhang S, Chu J. Reliable high-throughput approach for screening of engineered constitutive promoters in the yeast Pichia pastoris. Lett Appl Microbiol 2011; 52:634-41. [PMID: 21449926 DOI: 10.1111/j.1472-765x.2011.03051.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
AIMS To develop a reliable and sensitive high-throughput approach for the screening of engineered constitutive promoters in the yeast Pichia pastoris. METHODS AND RESULTS The yeast-enhanced green fluorescent protein (yEGFP) was used as the reporter to monitor the promoter strength. After eliminating the interfering components (yeast extract and tryptone) with fluorescence signal from the medium, a high-throughput screening approach was established and optimized to obtain a low standard deviation of cell density (6.9%) and fluorescence (7.4%) in 48-deep-well microplates. Then, 300 clones containing GAP promoter (P(GAP)) variants were screened, exhibiting a wide range in fluorescent intensity from about 8% to 218% of that obtained with P(GAP). Six representative clones with unique promoter sequence were picked for further characterization. A good correlation between yEGFP fluorescence in microplates and shake flasks was observed. Furthermore, the high correlation between fluorescence and transcript levels confirmed that expression was transcriptionally controlled. CONCLUSIONS We developed a reliable high-throughput screening approach that can be used to select engineered constitutive promoters of varying strengths. SIGNIFICANCE AND IMPACT OF THE STUDY This approach is expected to accelerate the selection of constitutive promoters in P. pastoris and can also be applied for the screening of other constitutive expression clones.
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Affiliation(s)
- X Qin
- State Key Laboratory of Bioreactor Engineering, East China University of Science & Technology, Shanghai, China
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114
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Abad S, Nahalka J, Winkler M, Bergler G, Speight R, Glieder A, Nidetzky B. High-level expression of Rhodotorula gracilis D-amino acid oxidase in Pichia pastoris. Biotechnol Lett 2010; 33:557-63. [PMID: 21053050 DOI: 10.1007/s10529-010-0456-9] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2010] [Accepted: 10/22/2010] [Indexed: 12/01/2022]
Abstract
By combining gene design and heterologous over-expression of Rhodotorula gracilis D-amino acid oxidase (RgDAO) in Pichia pastoris, enzyme production was enhanced by one order of magnitude compared to literature benchmarks, giving 350 kUnits/l of fed-batch bioreactor culture with a productivity of 3.1 kUnits/l h. P. pastoris cells permeabilized by freeze-drying and incubation in 2-propanol (10% v/v) produce a highly active (1.6 kUnits/g dry matter) and stable oxidase preparation. Critical bottlenecks in the development of an RgDAO catalyst for industrial applications have been eliminated.
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Affiliation(s)
- Sandra Abad
- Austrian Centre of Industrial Biotechnology, Petersgasse 14, Graz, 8010, Austria
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115
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High-throughput screening and selection of yeast cell lines expressing monoclonal antibodies. J Ind Microbiol Biotechnol 2010; 37:961-71. [DOI: 10.1007/s10295-010-0746-1] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2010] [Accepted: 05/06/2010] [Indexed: 12/27/2022]
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116
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Cambon E, Piamtongkam R, Bordes F, Duquesne S, Laguerre S, Nicaud JM, Marty A. A new Yarrowia lipolytica expression system: An efficient tool for rapid and reliable kinetic analysis of improved enzymes. Enzyme Microb Technol 2010. [DOI: 10.1016/j.enzmictec.2010.06.001] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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117
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Ruth C, Zuellig T, Mellitzer A, Weis R, Looser V, Kovar K, Glieder A. Variable production windows for porcine trypsinogen employing synthetic inducible promoter variants in Pichia pastoris. SYSTEMS AND SYNTHETIC BIOLOGY 2010; 4:181-91. [PMID: 21886682 DOI: 10.1007/s11693-010-9057-0] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/16/2009] [Accepted: 05/03/2010] [Indexed: 11/26/2022]
Abstract
Natural tools for recombinant protein production show technological limitations. Available natural promoters for gene expression in Pichia pastoris are either constitutive, weak or require the use of undesirable substances or procedures for induction. Here we show the application of deletion variants based on the well known methanol inducible AOX1 promoter and small synthetic promoters, where cis-acting elements were fused to core promoter fragments. They enable differently regulated target protein expression and at the same time to replace methanol induction by a glucose or glycerol feeding strategy. Trypsinogen, the precursor of the serine protease trypsin, was expressed using these different promoters. Depending on the applied promoter the production window (i.e. the time of increasing product concentration) changed significantly. In fedbatch processes trypsinogen yields before induction with methanol were up to 10 times higher if variants of the AOX1 promoter were applied. In addition, the starting point of autoproteolytic product degradation can be predetermined by the promoter choice.
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118
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Combined use of fluorescent dyes and flow cytometry to quantify the physiological state of Pichia pastoris during the production of heterologous proteins in high-cell-density fed-batch cultures. Appl Environ Microbiol 2010; 76:4486-96. [PMID: 20472737 DOI: 10.1128/aem.02475-09] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Matching both the construction of a recombinant strain and the process design with the characteristics of the target protein has the potential to significantly enhance bioprocess performance, robustness, and reproducibility. The factors affecting the physiological state of recombinant Pichia pastoris Mut(+) (methanol utilization-positive) strains and their cell membranes were quantified at the individual cell level using a combination of staining with fluorescent dyes and flow cytometric enumeration. Cell vitalities were found to range from 5 to 95% under various process conditions in high-cell-density fed-batch cultures, with strains producing either porcine trypsinogen or horseradish peroxidase extracellularly. Impaired cell vitality was observed to be the combined effect of production of recombinant protein, low pH, and high cell density. Vitality improved when any one of these stress factors was excluded. At a pH value of 4, which is commonly applied to counter proteolysis, recombinant strains exhibited severe physiological stress, whereas strains without heterologous genes were not affected. Physiologically compromised cells were also found to be increasingly sensitive to methanol when it accumulated in the culture broth. The magnitude of the response varied when different reporters were combined with either the native AOX1 promoter or its d6* variant, which differ in both strength and regulation. Finally, the quantitative assessment of the physiology of individual cells enables the implementation of innovative concepts in bioprocess development. Such concepts are in contrast to the frequently used paradigm, which always assumes a uniform cell population, because differentiation between the individual cells is not possible with methods commonly used.
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119
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Abad S, Nahalka J, Bergler G, Arnold SA, Speight R, Fotheringham I, Nidetzky B, Glieder A. Stepwise engineering of a Pichia pastoris D-amino acid oxidase whole cell catalyst. Microb Cell Fact 2010; 9:24. [PMID: 20420682 PMCID: PMC2873405 DOI: 10.1186/1475-2859-9-24] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2009] [Accepted: 04/26/2010] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Trigonopsis variabilis D-amino acid oxidase (TvDAO) is a well characterized enzyme used for cephalosporin C conversion on industrial scale. However, the demands on the enzyme with respect to activity, operational stability and costs also vary with the field of application. Processes that use the soluble enzyme suffer from fast inactivation of TvDAO while immobilized oxidase preparations raise issues related to expensive carriers and catalyst efficiency. Therefore, oxidase preparations that are more robust and active than those currently available would enable a much broader range of economically viable applications of this enzyme in fine chemical syntheses. A multi-step engineering approach was chosen here to develop a robust and highly active Pichia pastoris TvDAO whole-cell biocatalyst. RESULTS As compared to the native T. variabilis host, a more than seven-fold enhancement of the intracellular level of oxidase activity was achieved in P. pastoris through expression optimization by codon redesign as well as efficient subcellular targeting of the enzyme to peroxisomes. Multi copy integration further doubled expression and the specific activity of the whole cell catalyst. From a multicopy production strain, about 1.3 x 103 U/g wet cell weight (wcw) were derived by standard induction conditions feeding pure methanol. A fed-batch cultivation protocol using a mixture of methanol and glycerol in the induction phase attenuated the apparent toxicity of the recombinant oxidase to yield final biomass concentrations in the bioreactor of >or= 200 g/L compared to only 117 g/L using the standard methanol feed. Permeabilization of P. pastoris using 10% isopropanol yielded a whole-cell enzyme preparation that showed 49% of the total available intracellular oxidase activity and was notably stabilized (by three times compared to a widely used TvDAO expressing Escherichia coli strain) under conditions of D-methionine conversion using vigorous aeration. CONCLUSIONS Stepwise optimization using a multi-level engineering approach has delivered a new P. pastoris whole cell TvDAO biocatalyst showing substantially enhanced specific activity and stability under operational conditions as compared to previously reported preparations of the enzyme. The production of the oxidase through fed-batch bioreactor culture and subsequent cell permeabilization is high-yielding and efficient. Therefore this P. pastoris catalyst has been evaluated for industrial purposes.
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Affiliation(s)
- Sandra Abad
- Austrian Centre of Industrial Biotechnology, Graz University of Technology, Petersgasse 14, 8010 Graz, Austria
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120
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Abad S, Kitz K, Hörmann A, Schreiner U, Hartner FS, Glieder A. Real-time PCR-based determination of gene copy numbers inPichia pastoris. Biotechnol J 2010; 5:413-20. [DOI: 10.1002/biot.200900233] [Citation(s) in RCA: 99] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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121
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Fernández L, Jiao N, Soni P, Gumulya Y, de Oliveira LG, Reetz MT. An efficient method for mutant library creation inPichia pastorisuseful in directed evolution. BIOCATAL BIOTRANSFOR 2010. [DOI: 10.3109/10242420903505834] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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122
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Microlitre/millilitre shaken bioreactors in fermentative and biotransformation processes – a review. BIOCATAL BIOTRANSFOR 2009. [DOI: 10.1080/10242420600667684] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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123
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Winkler A, Motz K, Riedl S, Puhl M, Macheroux P, Gruber K. Structural and mechanistic studies reveal the functional role of bicovalent flavinylation in berberine bridge enzyme. J Biol Chem 2009; 284:19993-20001. [PMID: 19457868 DOI: 10.1074/jbc.m109.015727] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Berberine bridge enzyme (BBE) is a member of the recently discovered family of bicovalently flavinylated proteins. In this group of enzymes, the FAD cofactor is linked via its 8alpha-methyl group and the C-6 atom to conserved histidine and cysteine residues, His-104 and Cys-166 for BBE, respectively. 6-S-Cysteinylation has recently been shown to have a significant influence on the redox potential of the flavin cofactor; however, 8alpha-histidylation evaded a closer characterization due to extremely low expression levels upon substitution. Co-overexpression of protein disulfide isomerase improved expression levels and allowed isolation and purification of the H104A protein variant. To gain more insight into the functional role of the unusual dual mode of cofactor attachment, we solved the x-ray crystal structures of two mutant proteins, H104A and C166A BBE, each lacking one of the covalent linkages. Information from a structure of wild type enzyme in complex with the product of the catalyzed reaction is combined with the kinetic and structural characterization of the protein variants to demonstrate the importance of the bicovalent linkage for substrate binding and efficient oxidation. In addition, the redox potential of the flavin cofactor is enhanced additively by the dual mode of cofactor attachment. The reduced level of expression for the H104A mutant protein and the difficulty of isolating even small amounts of the protein variant with both linkages removed (H104A-C166A) also points toward a possible role of covalent flavinylation during protein folding.
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Affiliation(s)
- Andreas Winkler
- Institute of Biochemistry, Graz University of Technology, 8010 Graz, Austria
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124
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Possee RD, Hitchman RB, Richards KS, Mann SG, Siaterli E, Nixon CP, Irving H, Assenberg R, Alderton D, Owens RJ, King LA. Generation of baculovirus vectors for the high-throughput production of proteins in insect cells. Biotechnol Bioeng 2008; 101:1115-22. [PMID: 18781697 DOI: 10.1002/bit.22002] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
The baculovirus expression system is one of the most popular methods used for the production of recombinant proteins but has several complex steps which have proved inherently difficult to adapt to a multi-parallel process. We have developed a bacmid vector that does not require any form of selection pressure to separate recombinant virus from non-recombinant parental virus. The method relies on homologous recombination in insect cells between a transfer vector containing a gene to be expressed and a replication-deficient bacmid. The target gene replaces a bacterial replicon at the polyhedrin loci, simultaneously restoring a virus gene essential for replication. Therefore, only recombinant virus can replicate facilitating the rapid production of multiple recombinant viruses on automated platforms in a one-step procedure. Using this vector allowed us to automate the generation of multiple recombinant viruses with a robotic liquid handler and then rapidly screen infected insect cell supernatant for the presence of secreted proteins.
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Affiliation(s)
- Robert D Possee
- National Environmental Research Council, Centre for Hydrology & Ecology, Oxford, UK
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125
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Hartner FS, Ruth C, Langenegger D, Johnson SN, Hyka P, Lin-Cereghino GP, Lin-Cereghino J, Kovar K, Cregg JM, Glieder A. Promoter library designed for fine-tuned gene expression in Pichia pastoris. Nucleic Acids Res 2008; 36:e76. [PMID: 18539608 PMCID: PMC2475614 DOI: 10.1093/nar/gkn369] [Citation(s) in RCA: 219] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/05/2022] Open
Abstract
Although frequently used as protein production host, there is only a limited set of promoters available to drive the expression of recombinant proteins in Pichia pastoris. Fine-tuning of gene expression is often needed to maximize product yield and quality. However, for efficient knowledge-based engineering, a better understanding of promoter function is indispensable. Consequently, we created a promoter library by deletion and duplication of putative transcription factor-binding sites within the AOX1 promoter (PAOX1) sequence. This first library initially spanned an activity range between ∼6% and >160% of the wild-type promoter activity. After characterization of the promoter library employing a green fluorescent protein (GFP) variant, the new regulatory toolbox was successfully utilized in a ‘real case’, i.e. the expression of industrial enzymes. Characterization of the library under repressing, derepressing and inducing conditions displayed at least 12 cis-acting elements involved in PAOX1-driven high-level expression. Based on this deletion analysis, novel short artificial promoter variants were constructed by combining cis-acting elements with basal promoter. In addition to improving yields and quality of heterologous protein production, the new PAOX1 synthetic promoter library constitutes a basic toolbox to fine-tune gene expression in metabolic engineering and sequential induction of protein expression in synthetic biology.
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Affiliation(s)
- Franz S Hartner
- Institute of Molecular Biotechnology, Graz University of Technology, Graz, Austria
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126
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Liu Z, Pscheidt B, Avi M, Gaisberger R, Hartner FS, Schuster C, Skranc W, Gruber K, Glieder A. Laboratory Evolved Biocatalysts for Stereoselective Syntheses of Substituted Benzaldehyde Cyanohydrins. Chembiochem 2008; 9:58-61. [DOI: 10.1002/cbic.200700514] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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127
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Kern A, Hartner FS, Freigassner M, Spielhofer J, Rumpf C, Leitner L, Fröhlich KU, Glieder A. Pichia pastoris "just in time" alternative respiration. MICROBIOLOGY-SGM 2007; 153:1250-1260. [PMID: 17379734 DOI: 10.1099/mic.0.2006/001404-0] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Alternative oxidases (Aox or Aod) are present in the mitochondria of plants, fungi and many types of yeast. These enzymes transfer electrons from the ubiquinol pool directly to oxygen without contributing to the proton transfer across the mitochondrial membrane. Alternative oxidases are involved in stress responses, programmed cell death and maintenance of the cellular redox balance. The alternative oxidase gene of the methylotrophic yeast Pichia pastoris was isolated and cloned to study its regulation and the effects of deregulation of the alternative respiration by overexpression or disruption of the gene. Both disruption and overexpression had negative effects on the biomass yield; however, the growth rate and substrate uptake rate of the strain overexpressing the alternative oxidase were slightly increased. These effects were even more pronounced when higher glucose concentrations were used. The occurrence of free intracellular radicals and cell death phenomena was investigated using dihydrorhodamine 123 and the TUNEL test. The results suggest a major contribution of the alternative oxidase to P. pastoris cell viability. The negative effects of deregulated alternative respiration clearly indicated the importance of precise regulation of the alternative oxidase in this yeast.
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Affiliation(s)
- Alexander Kern
- Institute for Molecular Biotechnology, Graz University of Technology, Petersgasse 14/2, A-8010 Graz, Austria
| | - Franz S Hartner
- Institute for Molecular Biotechnology, Graz University of Technology, Petersgasse 14/2, A-8010 Graz, Austria
| | - Maria Freigassner
- Institute for Molecular Biotechnology, Graz University of Technology, Petersgasse 14/2, A-8010 Graz, Austria
| | - Julia Spielhofer
- Institute for Molecular Biosciences, Karl-Franzens University, Universitaetsplatz 2, A-8010 Graz, Austria
| | - Cornelia Rumpf
- Institute for Molecular Biosciences, Karl-Franzens University, Universitaetsplatz 2, A-8010 Graz, Austria
| | - Laura Leitner
- Institute for Molecular Biosciences, Karl-Franzens University, Universitaetsplatz 2, A-8010 Graz, Austria
| | - Kai-Uwe Fröhlich
- Institute for Molecular Biosciences, Karl-Franzens University, Universitaetsplatz 2, A-8010 Graz, Austria
| | - Anton Glieder
- Institute for Molecular Biotechnology, Graz University of Technology, Petersgasse 14/2, A-8010 Graz, Austria
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128
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Microtiter plates as mini-bioreactors: miniaturization of fermentation methods. Trends Microbiol 2007; 15:469-75. [DOI: 10.1016/j.tim.2007.09.004] [Citation(s) in RCA: 179] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2007] [Revised: 07/31/2007] [Accepted: 09/24/2007] [Indexed: 01/08/2023]
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129
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Bordes F, Fudalej F, Dossat V, Nicaud JM, Marty A. A new recombinant protein expression system for high-throughput screening in the yeast Yarrowia lipolytica. J Microbiol Methods 2007; 70:493-502. [PMID: 17669530 DOI: 10.1016/j.mimet.2007.06.008] [Citation(s) in RCA: 86] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2007] [Revised: 06/05/2007] [Accepted: 06/08/2007] [Indexed: 10/23/2022]
Abstract
Development of a high-throughput eukaryotic screening procedure is important to increase success in obtaining improved enzymes through directed enzyme evolution. This procedure was developed for the yeast Yarrowia lipolytica which becomes the second eukaryotic host for this purpose. The extracellular lipase Lip2 was used as expressed enzyme but this system will be easily adjusted for other enzymes. We adapted and optimized the protocol for protein expression by Y. lipolytica in 96-well microplates. Yeast transformation efficiency and expression cassette insertion were increased by constructing a strain containing a zeta docking platform for targeted integration into the genome. The coefficient of variance of the full process was reduced from 36.3% to 18.9%. The main part of the variability (11.7%) arises from the specific lipase enzyme assay whereas the coefficient of variance concerning transformation, growth and expression steps represents only 7.2%. The rate of clone with no activity was reduced from 5.8% to 0.2%. Both transformation efficiency and variability are then compatible with high-throughput screening in the yeast Y. lipolytica.
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Affiliation(s)
- Florence Bordes
- UMR5504, UMR792 Ingénierie des Systèmes Biologiques et des Procédés, CNRS, INRA, INSA, 135 Rangueil av., F-31400 Toulouse, France
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130
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Gaisberger R, Weis R, Luiten R, Skranc W, Wubbolts M, Griengl H, Glieder A. Counteracting expression deficiencies by anticipating posttranslational modification of PaHNL5-L1Q-A111G by genetic engineering. J Biotechnol 2007; 129:30-8. [PMID: 17234294 DOI: 10.1016/j.jbiotec.2006.12.003] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2005] [Revised: 08/11/2006] [Accepted: 10/09/2006] [Indexed: 10/23/2022]
Abstract
(R)-2-chloromandelic acid represents a key pharmaceutical intermediate. Its production on large scale was hampered by low turnover rates and moderate enantiomeric excess (ee) using enzyme as well as metal catalysts. The cloning and heterologous overexpression of an (R)-hydroxynitrile lyase from Prunus amygdalus opened a way to large-scale production of this compound. Especially the rationally designed mutation of alanine to glycine at amino acid position 111 of the mature protein tremendously raised the yield for enantioselective conversion of 2-chlorobenzaldehyde to (R)-2-chloromandelonitrile, which can be hydrolysed to the corresponding alpha hydroxy acid. However, expression of this mutein was less efficient than for the unmodified enzyme. Subsequent LC/MS/MS-analysis of the protein sequence revealed that mutation A111G triggered the posttranslational deamidation of the neighbouring residue asparagine (N110) to aspartic acid. This finding on the one hand could explain the decreased secretion efficiency of the mutant as compared to the wildtype enzyme, but on the other hand raised the question which of the two residues was truly accountable for the enhanced conversion. The muteins N110D, A111G and N110DA111G were constructed and compared in terms of protein productivity and performance in chemical syntheses. The expression level of the double mutein was augmented significantly and the enantioselectivity remained high. Reduced protein expression of mutein PaHNL5-L1Q-A111G was remedied by mutational anticipation of posttranslational deamidation.
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Affiliation(s)
- Richard Gaisberger
- Research Centre Applied Biocatalysis, Institute of Organic Chemistry, Graz University of Technology, Stremayrgasse 16, A-8010 Graz, Austria
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131
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Weis R, Gaisberger R, Gruber K, Glieder A. Serine scanning—A tool to prove the consequences of N-glycosylation of proteins. J Biotechnol 2007; 129:50-61. [PMID: 17224199 DOI: 10.1016/j.jbiotec.2006.12.001] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2005] [Revised: 08/02/2006] [Accepted: 08/15/2006] [Indexed: 11/20/2022]
Abstract
N-Glycosylation of proteins is a common posttranslational modification in eukaryotes. Often this results in enhanced protein stability through protection by the attached sugar moieties. Due to its 13 potential N-glycosylation motifs (N-X-T/S), recombinant hydroxynitrile lyase isoenzyme 5 from almonds (PaHNL5) is secreted by the heterologous host Pichia pastoris in a massively glycosylated form, and it shows extraordinary stability at low pH. The importance of N-glycosylation in general, and individual glycosylation sites in particular for stability at low pH were investigated. To identify especially important glycosylation sites asparagine from all N-X-S/T-motifs was replaced by serine. Thus, critical sites, which contributed to overall enzyme activity and/or stability, were identified individually. One glycosylation site revealed to be essential for stability at low pH. After enzymatic deglycosylation, leaving only one acetylglucosamine attached to asparagines, PaHNL5 retained most of its stability at low pH. Protonation effects in the active site as well as higher-order aggregational events upon incubation in low pH were excluded. This study provides evidence for the interconnection of N-glycosylation and stability at low pH for PaHNL5. Moreover, serine scanning was proven to be applicable for quick identification of critical glycosylation sites.
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Affiliation(s)
- Roland Weis
- Research Centre Applied Biocatalysis, Graz, Austria
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132
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Hartner FS, Glieder A. Regulation of methanol utilisation pathway genes in yeasts. Microb Cell Fact 2006; 5:39. [PMID: 17169150 PMCID: PMC1781073 DOI: 10.1186/1475-2859-5-39] [Citation(s) in RCA: 162] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2006] [Accepted: 12/14/2006] [Indexed: 11/10/2022] Open
Abstract
Methylotrophic yeasts such as Candida boidinii, Hansenula polymorpha, Pichia methanolica and Pichia pastoris are an emerging group of eukaryotic hosts for recombinant protein production with an ever increasing number of applications during the last 30 years. Their applications are linked to the use of strong methanol-inducible promoters derived from genes of the methanol utilisation pathway. These promoters are tightly regulated, highly repressed in presence of non-limiting concentrations of glucose in the medium and strongly induced if methanol is used as carbon source. Several factors involved in this tight control and their regulatory effects have been described so far. This review summarises available data about the regulation of promoters from methanol utilisation pathway genes. Furthermore, the role of cis and trans acting factors (e.g. transcription factors, glucose processing enzymes) in the expression of methanol utilisation pathway genes is reviewed both in the context of the native cell environment as well as in heterologous hosts.
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Affiliation(s)
- Franz S Hartner
- Research Centre Applied Biocatalysis GmbH, Petersgasse 14/2, 8010 Graz, Austria
| | - Anton Glieder
- Institute of Molecular Biotechnology, Graz University of Technology, Petersgasse 14/2, 8010 Graz, Austria
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133
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Winkler A, Hartner F, Kutchan TM, Glieder A, Macheroux P. Biochemical evidence that berberine bridge enzyme belongs to a novel family of flavoproteins containing a bi-covalently attached FAD cofactor. J Biol Chem 2006; 281:21276-21285. [PMID: 16728404 DOI: 10.1074/jbc.m603267200] [Citation(s) in RCA: 100] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Berberine bridge enzyme (BBE) is involved in the transformation of (S)-reticuline to (S)-scoulerine in benzophenanthridine alkaloid biosynthesis of plants. In this report, we describe the high level expression of BBE encoded by the gene from Eschscholzia californica (California poppy) in the methylotrophic yeast Pichia pastoris employing the secretory pathway of the host organism. Using a two-step chromatographic purification protocol, 120 mg of BBE could be obtained from 1 liter of fermentation culture. The purified protein exhibits a turnover number for substrate conversion of 8.2 s(-1). The recombinant enzyme is glycosylated and carries a covalently attached FAD cofactor. In addition to the previously known covalent attachment of the 8alpha-position of the flavin ring system to a histidine (His-104), we could also demonstrate that a covalent linkage between the 6-position and a thiol group of a cysteine residue (Cys-166) is present in BBE. The major evidence for the occurrence of a bi-covalently attached FAD cofactor is provided by N-terminal amino acid sequencing and mass spectrometric analysis of the isolated flavin-containing peptide. Furthermore, it could be shown that anaerobic photoirradiation leads to cleavage of the linkage between the 6-cysteinyl group yielding 6-mercaptoflavin and a peptide with the cysteine residue replaced by alanine due to breakage of the C-S bond. Overall, BBE is shown to exhibit typical flavoprotein oxidase properties as exemplified by the occurrence of an anionic flavin semiquinone species and formation of a flavin N(5)-sulfite adduct.
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Affiliation(s)
- Andreas Winkler
- Graz University of Technology, Institute of Biochemistry, Petersgasse 12/II, A-8010 Graz, Austria
| | - Franz Hartner
- Research Centre Applied Biocatalysis, c/o Graz University of Technology, Institute of Molecular Biotechnology, A-8010 Graz, Austria
| | - Toni M Kutchan
- Abteilung Naturstoff-Biotechnologie, Leibniz-Institut für Pflanzenbiochemie, D-06120 Halle/Saale, Germany
| | - Anton Glieder
- Research Centre Applied Biocatalysis, c/o Graz University of Technology, Institute of Molecular Biotechnology, A-8010 Graz, Austria
| | - Peter Macheroux
- Graz University of Technology, Institute of Biochemistry, Petersgasse 12/II, A-8010 Graz, Austria.
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