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Zhang S, Liu J, Xiao Z, Tan X, Wang Y, Zhao Y, Jiang N, Shan Y. Systems Metabolic Engineering of Saccharomyces cerevisiae for the High-Level Production of (2 S)-Eriodictyol. J Fungi (Basel) 2024; 10:119. [PMID: 38392791 PMCID: PMC10890390 DOI: 10.3390/jof10020119] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2023] [Revised: 01/21/2024] [Accepted: 01/30/2024] [Indexed: 02/24/2024] Open
Abstract
(2S)-eriodictyol (ERD) is a flavonoid widely found in citrus fruits, vegetables, and important medicinal plants with neuroprotective, cardioprotective, antidiabetic, and anti-obesity effects. However, the microbial synthesis of ERD is limited by complex metabolic pathways and often results in a low production performance. Here, we engineered Saccharomyces cerevisiae by fine-tuning the metabolism of the ERD synthesis pathway. The results showed that the ERD titer was effectively increased, and the intermediate metabolites levels were reduced. First, we successfully reconstructed the de novo synthesis pathway of p-coumaric acid in S. cerevisiae and fine-tuned the metabolic pathway using promoter engineering and terminator engineering for the high-level production of (2S)-naringenin. Subsequently, the synthesis of ERD was achieved by introducing the ThF3'H gene from Tricyrtis hirta. Finally, by multiplying the copy number of the ThF3'H gene, the production of ERD was further increased, reaching 132.08 mg L-1. Our work emphasizes the importance of regulating the metabolic balance to produce natural products in microbial cell factories.
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Affiliation(s)
- Siqi Zhang
- Longping Branch, College of Biology, Hunan University, Changsha 410125, China
- Agriculture Product Processing Institute, Hunan Academy of Agricultural Sciences, Changsha 410125, China
- Hunan Key Lab of Fruits & Vegetables Storage, Processing, Quality and Safety, Hunan Agricultural Products Processing Institute, Changsha 410125, China
| | - Juan Liu
- Longping Branch, College of Biology, Hunan University, Changsha 410125, China
- Agriculture Product Processing Institute, Hunan Academy of Agricultural Sciences, Changsha 410125, China
- Hunan Key Lab of Fruits & Vegetables Storage, Processing, Quality and Safety, Hunan Agricultural Products Processing Institute, Changsha 410125, China
- Department of Life Sciences, Chalmers University of Technology, SE412 96 Gothenburg, Sweden
| | - Zhiqiang Xiao
- Longping Branch, College of Biology, Hunan University, Changsha 410125, China
- Agriculture Product Processing Institute, Hunan Academy of Agricultural Sciences, Changsha 410125, China
- Hunan Key Lab of Fruits & Vegetables Storage, Processing, Quality and Safety, Hunan Agricultural Products Processing Institute, Changsha 410125, China
| | - Xinjia Tan
- Longping Branch, College of Biology, Hunan University, Changsha 410125, China
- Agriculture Product Processing Institute, Hunan Academy of Agricultural Sciences, Changsha 410125, China
- Hunan Key Lab of Fruits & Vegetables Storage, Processing, Quality and Safety, Hunan Agricultural Products Processing Institute, Changsha 410125, China
| | - Yongtong Wang
- Longping Branch, College of Biology, Hunan University, Changsha 410125, China
- Agriculture Product Processing Institute, Hunan Academy of Agricultural Sciences, Changsha 410125, China
- Hunan Key Lab of Fruits & Vegetables Storage, Processing, Quality and Safety, Hunan Agricultural Products Processing Institute, Changsha 410125, China
| | - Yifei Zhao
- Longping Branch, College of Biology, Hunan University, Changsha 410125, China
- Agriculture Product Processing Institute, Hunan Academy of Agricultural Sciences, Changsha 410125, China
- Hunan Key Lab of Fruits & Vegetables Storage, Processing, Quality and Safety, Hunan Agricultural Products Processing Institute, Changsha 410125, China
| | - Ning Jiang
- Longping Branch, College of Biology, Hunan University, Changsha 410125, China
- Agriculture Product Processing Institute, Hunan Academy of Agricultural Sciences, Changsha 410125, China
- Hunan Key Lab of Fruits & Vegetables Storage, Processing, Quality and Safety, Hunan Agricultural Products Processing Institute, Changsha 410125, China
| | - Yang Shan
- Longping Branch, College of Biology, Hunan University, Changsha 410125, China
- Agriculture Product Processing Institute, Hunan Academy of Agricultural Sciences, Changsha 410125, China
- Hunan Key Lab of Fruits & Vegetables Storage, Processing, Quality and Safety, Hunan Agricultural Products Processing Institute, Changsha 410125, China
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2
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Lei Q, Ma J, Du G, Zhou J, Guan X. Efficient expression of a cytokine combination in Saccharomyces cerevisiae for cultured meat production. Food Res Int 2023; 170:113017. [PMID: 37316083 DOI: 10.1016/j.foodres.2023.113017] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2023] [Revised: 05/16/2023] [Accepted: 05/19/2023] [Indexed: 06/16/2023]
Abstract
Cultured meat technology is a novel and promising alternative strategy for meat production, and it provides an efficient, safe, and sustainable way to supply animal protein. Cytokines play an important role in promoting the rapid proliferation of cells, but the high cost and potential food safety concerns of commercial cytokines have hindered their application in large-scale cultured meat production. Herein, Saccharomyces cerevisiae C800 was used as a starting strain in which four cytokines were exogenously expressed simultaneously using the Cre-loxP system, including long-chain human insulin growth factor-1, platelet-derived growth factor-BB, basic fibroblast growth factor, and epidermal growth factor. Through promoter optimization, endogenous protease knockout, genomic co-expression, expression frame gene order optimization, and fermentation optimization, a recombinant strain CPK2B2 co-expressing four cytokines was obtained with a yield of 18.35 mg/L. After cell lysis and filter sterilization, the CPK2B2 lysate was directly added to the culture medium of porcine muscle satellite cells (MuSCs). CPK2B2 lysate promoted the growth of MuSCs and increased the proportion of G2/S cells and EdU+ cells significantly, indicating its efficacy in promoting cell proliferation. This study provides a simple and cost-saving strategy by using S. cerevisiae to produce a recombinant cytokine combination for cultured meat production.
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Affiliation(s)
- Qingzi Lei
- Science Center for Future Foods, Jiangnan University, 1800 Lihu Road, Wuxi, Jiangsu 214122, China; Engineering Research Center of Ministry of Education on Food Synthetic Biotechnology, Jiangnan University, 1800 Lihu Road, Wuxi, Jiangsu 214122, China
| | - Jun Ma
- Science Center for Future Foods, Jiangnan University, 1800 Lihu Road, Wuxi, Jiangsu 214122, China; Engineering Research Center of Ministry of Education on Food Synthetic Biotechnology, Jiangnan University, 1800 Lihu Road, Wuxi, Jiangsu 214122, China
| | - Guocheng Du
- Science Center for Future Foods, Jiangnan University, 1800 Lihu Road, Wuxi, Jiangsu 214122, China; Engineering Research Center of Ministry of Education on Food Synthetic Biotechnology, Jiangnan University, 1800 Lihu Road, Wuxi, Jiangsu 214122, China
| | - Jingwen Zhou
- Science Center for Future Foods, Jiangnan University, 1800 Lihu Road, Wuxi, Jiangsu 214122, China; Engineering Research Center of Ministry of Education on Food Synthetic Biotechnology, Jiangnan University, 1800 Lihu Road, Wuxi, Jiangsu 214122, China.
| | - Xin Guan
- Science Center for Future Foods, Jiangnan University, 1800 Lihu Road, Wuxi, Jiangsu 214122, China; Engineering Research Center of Ministry of Education on Food Synthetic Biotechnology, Jiangnan University, 1800 Lihu Road, Wuxi, Jiangsu 214122, China.
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3
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Zhao X, Yu H, Liang Q, Zhou J, Li J, Du G, Chen J. Stepwise Optimization of Inducible Expression System for the Functional Secretion of Horseradish Peroxidase in Saccharomyces cerevisiae. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2023; 71:4059-4068. [PMID: 36821527 DOI: 10.1021/acs.jafc.2c09117] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/18/2023]
Abstract
Horseradish peroxidase (HRP) is a plant-derived glycoprotein that can be developed as a food additive to cross-link proteins or biopolymers. Although Saccharomyces cerevisiae has advantages in the production of food-grade HRP, the low expressional level and inefficient secretion hindered its application values. After comparing the effects of constitutive and inducible expression on cell growth, the strength of HRP expression was roughly tuned by replacing core regions of the promoter in the GAL80-knockout strain and further finely tuned by terminator screening. Additionally, the most suitable signal peptide was selected, and the pre-peptide with pro-peptides was modified to balance the transport of HRP in the endoplasmic reticulum. The extracellular HRP activity of the best strain reached 13 506 U/L at the fermenter level, 330-fold higher than the previous result of 41 U/L in S. cerevisiae. The strategy can be applied to alleviate the inhibition of cell growth caused by the expression of toxic proteins and improve their secretion.
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Affiliation(s)
- Xinrui Zhao
- Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, 1800 Lihu Road, Wuxi, Jiangsu 214122, China
- Science Center for Future Foods, Jiangnan University, 1800 Lihu Road, Wuxi, Jiangsu 214122, China
- Jiangsu Province Engineering Research Center of Food Synthetic Biotechnology, Jiangnan University, 1800 Lihu Road, Wuxi, Jiangsu 214122, China
- Engineering Research Center of Ministry of Education on Food Synthetic Biotechnology, Jiangnan University, 1800 Lihu Road, Wuxi, Jiangsu 214122, China
| | - Haibo Yu
- Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, 1800 Lihu Road, Wuxi, Jiangsu 214122, China
- Science Center for Future Foods, Jiangnan University, 1800 Lihu Road, Wuxi, Jiangsu 214122, China
| | - Qingfeng Liang
- Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, 1800 Lihu Road, Wuxi, Jiangsu 214122, China
| | - Jingwen Zhou
- Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, 1800 Lihu Road, Wuxi, Jiangsu 214122, China
- Science Center for Future Foods, Jiangnan University, 1800 Lihu Road, Wuxi, Jiangsu 214122, China
- Jiangsu Province Engineering Research Center of Food Synthetic Biotechnology, Jiangnan University, 1800 Lihu Road, Wuxi, Jiangsu 214122, China
- Engineering Research Center of Ministry of Education on Food Synthetic Biotechnology, Jiangnan University, 1800 Lihu Road, Wuxi, Jiangsu 214122, China
| | - Jianghua Li
- Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, 1800 Lihu Road, Wuxi, Jiangsu 214122, China
- Science Center for Future Foods, Jiangnan University, 1800 Lihu Road, Wuxi, Jiangsu 214122, China
- Jiangsu Province Engineering Research Center of Food Synthetic Biotechnology, Jiangnan University, 1800 Lihu Road, Wuxi, Jiangsu 214122, China
- Engineering Research Center of Ministry of Education on Food Synthetic Biotechnology, Jiangnan University, 1800 Lihu Road, Wuxi, Jiangsu 214122, China
| | - Guocheng Du
- Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, 1800 Lihu Road, Wuxi, Jiangsu 214122, China
- Science Center for Future Foods, Jiangnan University, 1800 Lihu Road, Wuxi, Jiangsu 214122, China
- Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry of Education, Jiangnan University, 1800 Lihu Road, Wuxi, Jiangsu 214122, China
- Jiangsu Province Engineering Research Center of Food Synthetic Biotechnology, Jiangnan University, 1800 Lihu Road, Wuxi, Jiangsu 214122, China
- Engineering Research Center of Ministry of Education on Food Synthetic Biotechnology, Jiangnan University, 1800 Lihu Road, Wuxi, Jiangsu 214122, China
| | - Jian Chen
- Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, 1800 Lihu Road, Wuxi, Jiangsu 214122, China
- Science Center for Future Foods, Jiangnan University, 1800 Lihu Road, Wuxi, Jiangsu 214122, China
- Jiangsu Province Engineering Research Center of Food Synthetic Biotechnology, Jiangnan University, 1800 Lihu Road, Wuxi, Jiangsu 214122, China
- Engineering Research Center of Ministry of Education on Food Synthetic Biotechnology, Jiangnan University, 1800 Lihu Road, Wuxi, Jiangsu 214122, China
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4
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Ito Y, Ishigami M, Terai G, Nakamura Y, Hashiba N, Nishi T, Nakazawa H, Hasunuma T, Asai K, Umetsu M, Ishii J, Kondo A. A streamlined strain engineering workflow with genome-wide screening detects enhanced protein secretion in Komagataella phaffii. Commun Biol 2022; 5:561. [PMID: 35676418 PMCID: PMC9177720 DOI: 10.1038/s42003-022-03475-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2021] [Accepted: 05/11/2022] [Indexed: 11/26/2022] Open
Abstract
Expression of secreted recombinant proteins burdens the protein secretion machinery, limiting production. Here, we describe an approach to improving protein production by the non-conventional yeast Komagataella phaffii comprised of genome-wide screening for effective gene disruptions, combining them in a single strain, and recovering growth reduction by adaptive evolution. For the screen, we designed a multiwell-formatted, streamlined workflow to high-throughput assay of secretion of a single-chain small antibody, which is cumbersome to detect but serves as a good model of proteins that are difficult to secrete. Using the consolidated screening system, we evaluated >19,000 mutant strains from a mutant library prepared by a modified random gene-disruption method, and identified six factors for which disruption led to increased antibody production. We then combined the disruptions, up to quadruple gene knockouts, which appeared to contribute independently, in a single strain and observed an additive effect. Target protein and promoter were basically interchangeable for the effects of knockout genes screened. We finally used adaptive evolution to recover reduced cell growth by multiple gene knockouts and examine the possibility for further enhancing protein secretion. Our successful, three-part approach holds promise as a method for improving protein production by non-conventional microorganisms.
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Affiliation(s)
- Yoichiro Ito
- Engineering Biology Research Center, Kobe University, Kobe, Japan
- Graduate School of Science, Technology and Innovation, Kobe University, Kobe, Japan
| | - Misa Ishigami
- Technology Research Association of Highly Efficient Gene Design (TRAHED), Kobe, Japan
| | - Goro Terai
- Department of Computational Biology and Medical Sciences, Graduate School of Frontier Sciences, University of Tokyo, Chiba, Japan
| | - Yasuyuki Nakamura
- Engineering Biology Research Center, Kobe University, Kobe, Japan
- Graduate School of Science, Technology and Innovation, Kobe University, Kobe, Japan
| | - Noriko Hashiba
- Technology Research Association of Highly Efficient Gene Design (TRAHED), Kobe, Japan
| | - Teruyuki Nishi
- Graduate School of Science, Technology and Innovation, Kobe University, Kobe, Japan
- Bio-Pharma Research Laboratories, Kaneka Corporation, Takasago, Japan
| | - Hikaru Nakazawa
- Department of Biomolecular Engineering, Graduate School of Engineering, Tohoku University, Sendai, Japan
| | - Tomohisa Hasunuma
- Engineering Biology Research Center, Kobe University, Kobe, Japan
- Graduate School of Science, Technology and Innovation, Kobe University, Kobe, Japan
| | - Kiyoshi Asai
- Department of Computational Biology and Medical Sciences, Graduate School of Frontier Sciences, University of Tokyo, Chiba, Japan
| | - Mitsuo Umetsu
- Department of Biomolecular Engineering, Graduate School of Engineering, Tohoku University, Sendai, Japan
| | - Jun Ishii
- Engineering Biology Research Center, Kobe University, Kobe, Japan.
- Graduate School of Science, Technology and Innovation, Kobe University, Kobe, Japan.
| | - Akihiko Kondo
- Engineering Biology Research Center, Kobe University, Kobe, Japan.
- Graduate School of Science, Technology and Innovation, Kobe University, Kobe, Japan.
- Department of Chemical Science and Engineering, Graduate School of Engineering, Kobe University, Kobe, Japan.
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5
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Sharma J, Kumar V, Prasad R, Gaur NA. Engineering of Saccharomyces cerevisiae as a consolidated bioprocessing host to produce cellulosic ethanol: Recent advancements and current challenges. Biotechnol Adv 2022; 56:107925. [DOI: 10.1016/j.biotechadv.2022.107925] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2021] [Revised: 01/24/2022] [Accepted: 02/06/2022] [Indexed: 01/01/2023]
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6
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Han L, Cui W, Lin Q, Chen Q, Suo F, Ma K, Wang Y, Hao W, Cheng Z, Zhou Z. Efficient Overproduction of Active Nitrile Hydratase by Coupling Expression Induction and Enzyme Maturation via Programming a Controllable Cobalt-Responsive Gene Circuit. Front Bioeng Biotechnol 2020; 8:193. [PMID: 32266230 PMCID: PMC7105576 DOI: 10.3389/fbioe.2020.00193] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2019] [Accepted: 02/27/2020] [Indexed: 11/13/2022] Open
Abstract
A robust and portable expression system is of great importance in enzyme production, metabolic engineering, and synthetic biology, which maximizes the performance of the engineered system. In this study, a tailor-made cobalt-induced expression system (CIES) was developed for low-cost and eco-friendly nitrile hydratase (NHase) production. First, the strong promoter Pveg from Bacillus subtilis, the Ni(II)/Co(II) responsive repressor RcnR, and its operator were reorganized to construct a CIES. In this system, the expression of reporter green fluorescent protein (GFP) was specifically triggered by Co(II) over a broad range of concentration. The performance of the cobalt-induced system was evolved to version 2.0 (CIES 2.0) for adaptation to different concentrations of Co(II) through programming a homeostasis system that rebalances cobalt efflux and influx with RcnA and NiCoT, respectively. Harnessing these synthetic platforms, the induced expression of NHase was coupled with enzyme maturation by Co(II) in a synchronizable manner without requiring additional inducers, which is a unique feature relative to other induced systems for production of NHase. The yield of NHase was 111.2 ± 17.9 U/ml using CIES and 114.9 ± 1.4 U/ml using CIES 2.0, which has a producing capability equivalent to that of commonly used isopropyl thiogalactoside (IPTG)-induced systems. In a scale-up system using a 5-L fermenter, the yielded enzymatic activity reached 542.2 ± 42.8 U/ml, suggesting that the designer platform for NHase is readily applied to the industry. The design of CIES in this study not only provided a low-cost and eco-friendly platform to overproduce NHase but also proposed a promising pipeline for development of synthetic platforms for expression of metalloenzymes.
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Affiliation(s)
- Laichuang Han
- Key Laboratory of Industrial Biotechnology, School of Biotechnology, Jiangnan University, Jiangsu, China
| | - Wenjing Cui
- Key Laboratory of Industrial Biotechnology, School of Biotechnology, Jiangnan University, Jiangsu, China
| | - Qiao Lin
- Key Laboratory of Industrial Biotechnology, School of Biotechnology, Jiangnan University, Jiangsu, China
| | - Qiaoqing Chen
- Key Laboratory of Industrial Biotechnology, School of Biotechnology, Jiangnan University, Jiangsu, China
| | - Feiya Suo
- Key Laboratory of Industrial Biotechnology, School of Biotechnology, Jiangnan University, Jiangsu, China
| | - Ke Ma
- Key Laboratory of Industrial Biotechnology, School of Biotechnology, Jiangnan University, Jiangsu, China
| | - Yang Wang
- Key Laboratory of Industrial Biotechnology, School of Biotechnology, Jiangnan University, Jiangsu, China
| | - Wenliang Hao
- Key Laboratory of Industrial Biotechnology, School of Biotechnology, Jiangnan University, Jiangsu, China
| | - Zhongyi Cheng
- Key Laboratory of Industrial Biotechnology, School of Biotechnology, Jiangnan University, Jiangsu, China
| | - Zhemin Zhou
- Key Laboratory of Industrial Biotechnology, School of Biotechnology, Jiangnan University, Jiangsu, China
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7
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Rantasalo A, Landowski CP, Kuivanen J, Korppoo A, Reuter L, Koivistoinen O, Valkonen M, Penttilä M, Jäntti J, Mojzita D. A universal gene expression system for fungi. Nucleic Acids Res 2019; 46:e111. [PMID: 29924368 PMCID: PMC6182139 DOI: 10.1093/nar/gky558] [Citation(s) in RCA: 50] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2018] [Accepted: 06/07/2018] [Indexed: 12/02/2022] Open
Abstract
Biotechnological production of fuels, chemicals and proteins is dependent on efficient production systems, typically genetically engineered microorganisms. New genome editing methods are making it increasingly easy to introduce new genes and functionalities in a broad range of organisms. However, engineering of all these organisms is hampered by the lack of suitable gene expression tools. Here, we describe a synthetic expression system (SES) that is functional in a broad spectrum of fungal species without the need for host-dependent optimization. The SES consists of two expression cassettes, the first providing a weak, but constitutive level of a synthetic transcription factor (sTF), and the second enabling strong, at will tunable expression of the target gene via an sTF-dependent promoter. We validated the SES functionality in six yeast and two filamentous fungi species in which high (levels beyond organism-specific promoters) as well as adjustable expression levels of heterologous and native genes was demonstrated. The SES is an unprecedentedly broadly functional gene expression regulation method that enables significantly improved engineering of fungi. Importantly, the SES system makes it possible to take in use novel eukaryotic microbes for basic research and various biotechnological applications.
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Affiliation(s)
- Anssi Rantasalo
- VTT Technical Research Centre of Finland, Espoo, P.O. Box 1000, FI-02044 VTT, Finland
| | | | - Joosu Kuivanen
- VTT Technical Research Centre of Finland, Espoo, P.O. Box 1000, FI-02044 VTT, Finland
| | - Annakarin Korppoo
- VTT Technical Research Centre of Finland, Espoo, P.O. Box 1000, FI-02044 VTT, Finland
| | - Lauri Reuter
- VTT Technical Research Centre of Finland, Espoo, P.O. Box 1000, FI-02044 VTT, Finland
| | - Outi Koivistoinen
- VTT Technical Research Centre of Finland, Espoo, P.O. Box 1000, FI-02044 VTT, Finland
| | - Mari Valkonen
- VTT Technical Research Centre of Finland, Espoo, P.O. Box 1000, FI-02044 VTT, Finland
| | - Merja Penttilä
- VTT Technical Research Centre of Finland, Espoo, P.O. Box 1000, FI-02044 VTT, Finland
| | - Jussi Jäntti
- VTT Technical Research Centre of Finland, Espoo, P.O. Box 1000, FI-02044 VTT, Finland
| | - Dominik Mojzita
- VTT Technical Research Centre of Finland, Espoo, P.O. Box 1000, FI-02044 VTT, Finland
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8
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Matsuyama T. Recent developments in terminator technology in Saccharomyces cerevisiae. J Biosci Bioeng 2019; 128:655-661. [PMID: 31324384 DOI: 10.1016/j.jbiosc.2019.06.006] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2019] [Revised: 06/07/2019] [Accepted: 06/07/2019] [Indexed: 11/26/2022]
Abstract
Metabolically engineered microorganisms that produce useful organic compounds will be helpful for realizing a sustainable society. The budding yeast Saccharomyces cerevisiae has high utility as a metabolic engineering platform because of its high fermentation ability, non-pathogenicity, and ease of handling. When producing yeast strains that produce exogenous compounds, it is a prerequisite to control the expression of exogenous enzyme-encoding genes. Terminator region in a gene expression cassette, as well as promoter region, could be used to improve metabolically engineered yeasts by increasing or decreasing the expression of the target enzyme-encoding genes. The findings on terminators have grown rapidly in the last decade, so an overview of these findings should provide a foothold for new developments.
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9
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Strategies for gene disruption and expression in filamentous fungi. Appl Microbiol Biotechnol 2019; 103:6041-6059. [DOI: 10.1007/s00253-019-09953-2] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2019] [Revised: 05/24/2019] [Accepted: 05/28/2019] [Indexed: 02/02/2023]
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10
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Gene expression engineering in fungi. Curr Opin Biotechnol 2019; 59:141-149. [PMID: 31154079 DOI: 10.1016/j.copbio.2019.04.007] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2018] [Revised: 03/27/2019] [Accepted: 04/24/2019] [Indexed: 02/03/2023]
Abstract
Fungi are a highly diverse group of microbial species that possess a plethora of biotechnologically useful metabolic and physiological properties. Important enablers for fungal biology studies and their biotechnological use are well-performing gene expression tools. Different types of gene expression tools exist; however, typically they are at best only functional in one or a few closely related species. This has hampered research and development of industrially relevant production systems. Here, we review operational principles and concepts of fungal gene expression tools. We present an overview on tools that utilize endogenous fungal promoters and modified hybrid expression systems composed of engineered promoters and transcription factors. Finally, we review synthetic expression tools that are functional across a broad range of fungal species.
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11
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Zhang B, Yu M, Zhou Y, Ye BC. Improvement of L-ornithine production by attenuation of argF in engineered Corynebacterium glutamicum S9114. AMB Express 2018; 8:26. [PMID: 29478233 PMCID: PMC6890880 DOI: 10.1186/s13568-018-0557-8] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2018] [Accepted: 02/12/2018] [Indexed: 12/31/2022] Open
Abstract
l-Ornithine, a non-essential amino acid, has enormous industrial applications in food, pharmaceutical, and chemical industries. Currently, l-ornithine production is focused on microorganism fermentation using Escherichia coli or Corynebacterium glutamicum. In C. glutamicum, development of high l-ornithine producing C. glutamicum was achieved by deletion of argF, but was accompanied by growth deficiency and arginine auxotrophy. l-Arginine has been routinely added to solve this problem; however, this increases production cost and causes feedback inhibition of N-acetyl-l-glutamate kinase activity. To avoid the drawbacks of growth disturbance due to disruption of ArgF, strategies were adopted to attenuate its expression. Firstly, ribosome binding site substitution and start codon replacement were introduced to construct recombinant C. glutamiucm strains, which resulted in an undesirable l-ornithine production titer. Then, we inserted a terminator (rrnB) between argD and argF, which significantly improved l-ornithine production and relieved growth disturbance. Transcription analysis confirmed that a terminator can be used to downregulate expression of argF and simultaneously improve the transcriptional level of genes in front of argF. Using disparate terminators to attenuate expression of argF, an optimal strain (CO-9) with a T4 terminator produced 6.1 g/L of l-ornithine, which is 42.8% higher than that produced by strain CO-1, and is 11.2-fold higher than that of the parent CO strain. Insertion of terminators with gradient termination intensity can be a stable and powerful method to exert precise control of the expression level of argF in the development of l-ornithine producing strains, with potential applications in metabolic engineering and synthetic biology.
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12
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Wei L, Wang Z, Zhang G, Ye B. Characterization of Terminators in Saccharomyces cerevisiae and an Exploration of Factors Affecting Their Strength. Chembiochem 2017; 18:2422-2427. [PMID: 29058813 DOI: 10.1002/cbic.201700516] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2017] [Indexed: 11/06/2022]
Abstract
Terminators in eukaryotes play an important role in regulating the transcription process by influencing mRNA stability, translational efficiency, and localization. Herein, the strengths of 100 natural terminators in Saccharomyces cerevisiae have been characterized by inserting each terminator downstream of the TYS1p-enhanced green fluorescent protein (eGFP) reporter gene and measuring the fluorescent intensity (FI) of eGFP. Within this library, there are 45 strong terminators, 31 moderate terminators, and 24 weak terminators. The strength of these terminators, relative to that of PGK1t standard terminator, ranges from 0.0613 to 1.8002, with a mean relative FI of 0.9945. Mutating the control elements of terminators further suggests that the efficiency element has an important effect on terminator strength. The use of strong terminators will result in an enhanced level of mRNA and protein production; this indicates that gene expression can be directly influenced by terminator selection. Pairing a terminator with an inducible promoter or a strong constitutive promoter has less effect on gene expression; however, pairing with a week promoter will significantly increase the level of gene expression. Through exchange of the reporter genes, it can be demonstrated that the terminator functions as a genetic component and is independent of the coding region. This work demonstrates that the terminator is an important regulatory element and can be considered in applications for the fine-tuning of gene expression and metabolic pathways.
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Affiliation(s)
- Linna Wei
- School of Chemistry and Chemical Engineering, Key Laboratory for Green Processing of Chemical, Engineering of Xinjiang Bingtuan, Shihezi University, Shihezi, 832003, P.R. China
| | - Zhaoxia Wang
- School of Chemistry and Chemical Engineering, Key Laboratory for Green Processing of Chemical, Engineering of Xinjiang Bingtuan, Shihezi University, Shihezi, 832003, P.R. China
| | - Genlin Zhang
- School of Chemistry and Chemical Engineering, Key Laboratory for Green Processing of Chemical, Engineering of Xinjiang Bingtuan, Shihezi University, Shihezi, 832003, P.R. China
| | - Bangce Ye
- School of Chemistry and Chemical Engineering, Key Laboratory for Green Processing of Chemical, Engineering of Xinjiang Bingtuan, Shihezi University, Shihezi, 832003, P.R. China
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Song X, Liu Q, Mao J, Wu Y, Li Y, Gao K, Zhang X, Bai Y, Xu H, Qiao M. POT1-mediated δ-integration strategy for high-copy, stable expression of heterologous proteins in Saccharomyces cerevisiae. FEMS Yeast Res 2017; 17:4083647. [DOI: 10.1093/femsyr/fox064] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2017] [Accepted: 08/16/2017] [Indexed: 12/18/2022] Open
Affiliation(s)
- Xiaofei Song
- The Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, College of Life Sciences, Nankai University, No. 94 Weijin Road, Nankai District, Tianjin, China
| | - Quanli Liu
- The Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, College of Life Sciences, Nankai University, No. 94 Weijin Road, Nankai District, Tianjin, China
| | - Jiwei Mao
- The Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, College of Life Sciences, Nankai University, No. 94 Weijin Road, Nankai District, Tianjin, China
| | - Yuzhen Wu
- The Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, College of Life Sciences, Nankai University, No. 94 Weijin Road, Nankai District, Tianjin, China
| | - Yuanzi Li
- The Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, College of Life Sciences, Nankai University, No. 94 Weijin Road, Nankai District, Tianjin, China
| | - Kai Gao
- Tianjin Academy of Environmental Sciences, No. 17 Fukang Road, Nankai District, Tianjin, China
| | - Xiuming Zhang
- The Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, College of Life Sciences, Nankai University, No. 94 Weijin Road, Nankai District, Tianjin, China
| | - Yanling Bai
- The Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, College of Life Sciences, Nankai University, No. 94 Weijin Road, Nankai District, Tianjin, China
| | - Haijin Xu
- The Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, College of Life Sciences, Nankai University, No. 94 Weijin Road, Nankai District, Tianjin, China
| | - Mingqiang Qiao
- The Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, College of Life Sciences, Nankai University, No. 94 Weijin Road, Nankai District, Tianjin, China
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14
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Enhancement of protein production via the strong DIT1 terminator and two RNA-binding proteins in Saccharomyces cerevisiae. Sci Rep 2016; 6:36997. [PMID: 27845367 PMCID: PMC5109538 DOI: 10.1038/srep36997] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2016] [Accepted: 10/20/2016] [Indexed: 11/10/2022] Open
Abstract
Post-transcriptional upregulation is an effective way to increase the expression of transgenes and thus maximize the yields of target chemicals from metabolically engineered organisms. Refractory elements in the 3′ untranslated region (UTR) that increase mRNA half-life might be available. In Saccharomyces cerevisiae, several terminator regions have shown activity in increasing the production of proteins by upstream coding genes; among these terminators the DIT1 terminator has the highest activity. Here, we found in Saccharomyces cerevisiae that two resident trans-acting RNA-binding proteins (Nab6p and Pap1p) enhance the activity of the DIT1 terminator through the cis element GUUCG/U within the 3′-UTR. These two RNA-binding proteins could upregulate a battery of cell-wall–related genes. Mutagenesis of the DIT1 terminator improved its activity by a maximum of 500% of that of the standard PGK1 terminator. Further understanding and improvement of this system will facilitate inexpensive and stable production of complicated organism-derived drugs worldwide.
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Mattam AJ, Kuila A, Suralikerimath N, Choudary N, Rao PVC, Velankar HR. Cellulolytic enzyme expression and simultaneous conversion of lignocellulosic sugars into ethanol and xylitol by a new Candida tropicalis strain. BIOTECHNOLOGY FOR BIOFUELS 2016; 9:157. [PMID: 27462368 PMCID: PMC4960679 DOI: 10.1186/s13068-016-0575-1] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/06/2016] [Accepted: 07/14/2016] [Indexed: 05/31/2023]
Abstract
BACKGROUND Lignocellulosic ethanol production involves major steps such as thermochemical pretreatment of biomass, enzymatic hydrolysis of pre-treated biomass and the fermentation of released sugars into ethanol. At least two different organisms are conventionally utilized for producing cellulolytic enzymes and for ethanol production through fermentation, whereas in the present study a single yeast isolate with the capacity to simultaneously produce cellulases and xylanases and ferment the released sugars into ethanol and xylitol has been described. RESULTS A yeast strain isolated from soil samples and identified as Candida tropicalis MTCC 25057 expressed cellulases and xylanases over a wide range of temperatures (32 and 42 °C) and in the presence of different cellulosic substrates [carboxymethylcellulose and wheat straw (WS)]. The studies indicated that the cultivation of yeast at 42 °C in pre-treated hydrolysate containing 0.5 % WS resulted in proportional expression of cellulases (exoglucanases and endoglucanases) at concentrations of 114.1 and 97.8 U g(-1) ds, respectively. A high xylanase activity (689.3 U g(-1) ds) was also exhibited by the yeast under similar growth conditions. Maximum expression of cellulolytic enzymes by the yeast occurred within 24 h of incubation. Of the sugars released from biomass after pretreatment, 49 g L(-1) xylose was aerobically converted into 15.8 g L(-1) of xylitol. In addition, 25.4 g L(-1) glucose released after the enzymatic hydrolysis of biomass was fermented by the same yeast to obtain an ethanol titer of 7.3 g L(-1). CONCLUSIONS During the present study, a new strain of C. tropicalis was isolated and found to have potential for consolidated bioprocessing (CBP) applications. The strain could grow in a wide range of process conditions (temperature, pH) and in the presence of lignocellulosic inhibitors such as furfural, HMF and acetic acid. The new yeast produced cellulolytic enzymes over a wide temperature range and in the presence of various cellulosic substrates. The cellulolytic enzymes produced by the yeast were effectively used for the hydrolysis of pretreated biomass. The released sugars, xylose and glucose were, respectively, converted into xylitol and ethanol. The potential shown by the new inhibitor tolerant cellulolytic C. tropicalis to produce ethanol or xylitol is of great industrial significance.
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Affiliation(s)
- Anu Jose Mattam
- Bioprocess Group, Hindustan Petroleum Corporation Limited, HP Green R&D Centre, KIADB Industrial Area, Tarabahalli, Devanagundi, Hoskote, Bengaluru, 560067 India
| | - Arindam Kuila
- Bioprocess Group, Hindustan Petroleum Corporation Limited, HP Green R&D Centre, KIADB Industrial Area, Tarabahalli, Devanagundi, Hoskote, Bengaluru, 560067 India
| | - Niranjan Suralikerimath
- Bioprocess Group, Hindustan Petroleum Corporation Limited, HP Green R&D Centre, KIADB Industrial Area, Tarabahalli, Devanagundi, Hoskote, Bengaluru, 560067 India
| | - Nettem Choudary
- Bioprocess Group, Hindustan Petroleum Corporation Limited, HP Green R&D Centre, KIADB Industrial Area, Tarabahalli, Devanagundi, Hoskote, Bengaluru, 560067 India
| | - Peddy V. C. Rao
- Bioprocess Group, Hindustan Petroleum Corporation Limited, HP Green R&D Centre, KIADB Industrial Area, Tarabahalli, Devanagundi, Hoskote, Bengaluru, 560067 India
| | - Harshad Ravindra Velankar
- Bioprocess Group, Hindustan Petroleum Corporation Limited, HP Green R&D Centre, KIADB Industrial Area, Tarabahalli, Devanagundi, Hoskote, Bengaluru, 560067 India
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16
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Rantasalo A, Czeizler E, Virtanen R, Rousu J, Lähdesmäki H, Penttilä M, Jäntti J, Mojzita D. Synthetic Transcription Amplifier System for Orthogonal Control of Gene Expression in Saccharomyces cerevisiae. PLoS One 2016; 11:e0148320. [PMID: 26901642 PMCID: PMC4762949 DOI: 10.1371/journal.pone.0148320] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2015] [Accepted: 01/15/2016] [Indexed: 12/26/2022] Open
Abstract
This work describes the development and characterization of a modular synthetic expression system that provides a broad range of adjustable and predictable expression levels in S. cerevisiae. The system works as a fixed-gain transcription amplifier, where the input signal is transferred via a synthetic transcription factor (sTF) onto a synthetic promoter, containing a defined core promoter, generating a transcription output signal. The system activation is based on the bacterial LexA-DNA-binding domain, a set of modified, modular LexA-binding sites and a selection of transcription activation domains. We show both experimentally and computationally that the tuning of the system is achieved through the selection of three separate modules, each of which enables an adjustable output signal: 1) the transcription-activation domain of the sTF, 2) the binding-site modules in the output promoter, and 3) the core promoter modules which define the transcription initiation site in the output promoter. The system has a novel bidirectional architecture that enables generation of compact, yet versatile expression modules for multiple genes with highly diversified expression levels ranging from negligible to very strong using one synthetic transcription factor. In contrast to most existing modular gene expression regulation systems, the present system is independent from externally added compounds. Furthermore, the established system was minimally affected by the several tested growth conditions. These features suggest that it can be highly useful in large scale biotechnology applications.
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Affiliation(s)
- Anssi Rantasalo
- VTT Technical Research Centre of Finland, P.O. Box 1000, FI-02044 VTT, Espoo, Finland
| | - Elena Czeizler
- Helsinki Institute for Information Technology HIIT, Department of Computer Science, Aalto University, P.O. Box 15400, FI-00076 Aalto, Espoo, Finland
| | - Riitta Virtanen
- VTT Technical Research Centre of Finland, P.O. Box 1000, FI-02044 VTT, Espoo, Finland
| | - Juho Rousu
- Helsinki Institute for Information Technology HIIT, Department of Computer Science, Aalto University, P.O. Box 15400, FI-00076 Aalto, Espoo, Finland
| | - Harri Lähdesmäki
- Aalto University, Department of Computer Science, P.O. Box 15400, FI-00076 Aalto, Espoo, Finland
| | - Merja Penttilä
- VTT Technical Research Centre of Finland, P.O. Box 1000, FI-02044 VTT, Espoo, Finland
| | - Jussi Jäntti
- VTT Technical Research Centre of Finland, P.O. Box 1000, FI-02044 VTT, Espoo, Finland
| | - Dominik Mojzita
- VTT Technical Research Centre of Finland, P.O. Box 1000, FI-02044 VTT, Espoo, Finland
- * E-mail:
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17
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Ito Y, Yamanishi M, Ikeuchi A, Imamura C, Matsuyama T. Combinatorial Screening for Transgenic Yeasts with High Cellulase Activities in Combination with a Tunable Expression System. PLoS One 2015; 10:e0144870. [PMID: 26692026 PMCID: PMC4687128 DOI: 10.1371/journal.pone.0144870] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2015] [Accepted: 11/24/2015] [Indexed: 01/26/2023] Open
Abstract
Combinatorial screening used together with a broad library of gene expression cassettes is expected to produce a powerful tool for the optimization of the simultaneous expression of multiple enzymes. Recently, we proposed a highly tunable protein expression system that utilized multiple genome-integrated target genes to fine-tune enzyme expression in yeast cells. This tunable system included a library of expression cassettes each composed of three gene-expression control elements that in different combinations produced a wide range of protein expression levels. In this study, four gene expression cassettes with graded protein expression levels were applied to the expression of three cellulases: cellobiohydrolase 1, cellobiohydrolase 2, and endoglucanase 2. After combinatorial screening for transgenic yeasts simultaneously secreting these three cellulases, we obtained strains with higher cellulase expressions than a strain harboring three cellulase-expression constructs within one high-performance gene expression cassette. These results show that our method will be of broad use throughout the field of metabolic engineering.
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Affiliation(s)
- Yoichiro Ito
- Matsuyama Research Group, TOYOTA Central Research and Development Laboratories Incorporation, Nagakute, Aichi, Japan
- * E-mail: (TM); (YI)
| | - Mamoru Yamanishi
- Matsuyama Research Group, TOYOTA Central Research and Development Laboratories Incorporation, Nagakute, Aichi, Japan
| | - Akinori Ikeuchi
- Biotechnology Laboratory, TOYOTA Central Research and Development Laboratories Incorporation, Nagakute, Aichi, Japan
| | - Chie Imamura
- Biotechnology Laboratory, TOYOTA Central Research and Development Laboratories Incorporation, Nagakute, Aichi, Japan
| | - Takashi Matsuyama
- Matsuyama Research Group, TOYOTA Central Research and Development Laboratories Incorporation, Nagakute, Aichi, Japan
- * E-mail: (TM); (YI)
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18
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Hasunuma T, Ishii J, Kondo A. Rational design and evolutional fine tuning of Saccharomyces cerevisiae for biomass breakdown. Curr Opin Chem Biol 2015; 29:1-9. [DOI: 10.1016/j.cbpa.2015.06.004] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2015] [Revised: 06/06/2015] [Accepted: 06/08/2015] [Indexed: 12/31/2022]
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Lambertz C, Garvey M, Klinger J, Heesel D, Klose H, Fischer R, Commandeur U. Challenges and advances in the heterologous expression of cellulolytic enzymes: a review. BIOTECHNOLOGY FOR BIOFUELS 2014; 7:135. [PMID: 25356086 PMCID: PMC4212100 DOI: 10.1186/s13068-014-0135-5] [Citation(s) in RCA: 104] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/05/2014] [Accepted: 09/03/2014] [Indexed: 05/03/2023]
Abstract
Second generation biofuel development is increasingly reliant on the recombinant expression of cellulases. Designing or identifying successful expression systems is thus of preeminent importance to industrial progress in the field. Recombinant production of cellulases has been performed using a wide range of expression systems in bacteria, yeasts and plants. In a number of these systems, particularly when using bacteria and plants, significant challenges have been experienced in expressing full-length proteins or proteins at high yield. Further difficulties have been encountered in designing recombinant systems for surface-display of cellulases and for use in consolidated bioprocessing in bacteria and yeast. For establishing cellulase expression in plants, various strategies are utilized to overcome problems, such as the auto-hydrolysis of developing plant cell walls. In this review, we investigate the major challenges, as well as the major advances made to date in the recombinant expression of cellulases across the commonly used bacterial, plant and yeast systems. We review some of the critical aspects to be considered for industrial-scale cellulase production.
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Affiliation(s)
- Camilla Lambertz
- />Institute for Molecular Biotechnology, RWTH Aachen University, Worringerweg 1, 52074 Aachen, Germany
| | - Megan Garvey
- />Institute for Molecular Biotechnology, RWTH Aachen University, Worringerweg 1, 52074 Aachen, Germany
- />Present address: School of Medicine, Deakin University, CSIRO Australian Animal Health Laboratory, 5 Portarlington Rd, Newcomb, VIC 3219 Australia
| | - Johannes Klinger
- />Institute for Molecular Biotechnology, RWTH Aachen University, Worringerweg 1, 52074 Aachen, Germany
| | - Dirk Heesel
- />Institute for Molecular Biotechnology, RWTH Aachen University, Worringerweg 1, 52074 Aachen, Germany
| | - Holger Klose
- />Institute for Molecular Biotechnology, RWTH Aachen University, Worringerweg 1, 52074 Aachen, Germany
- />Present address: Institute for Botany and Molecular Genetics, RWTH Aachen University, Worringerweg 3, 52074 Aachen, Germany
| | - Rainer Fischer
- />Institute for Molecular Biotechnology, RWTH Aachen University, Worringerweg 1, 52074 Aachen, Germany
- />Fraunhofer Institute for Molecular Biology and Applied Ecology, Forckenbeckstrasse 6, 52074 Aachen, Germany
| | - Ulrich Commandeur
- />Institute for Molecular Biotechnology, RWTH Aachen University, Worringerweg 1, 52074 Aachen, Germany
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