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Gasparek M, Steel H, Papachristodoulou A. Deciphering mechanisms of production of natural compounds using inducer-producer microbial consortia. Biotechnol Adv 2023; 64:108117. [PMID: 36813010 DOI: 10.1016/j.biotechadv.2023.108117] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2022] [Revised: 02/03/2023] [Accepted: 02/06/2023] [Indexed: 02/22/2023]
Abstract
Living organisms produce a wide range of metabolites. Because of their potential antibacterial, antifungal, antiviral, or cytostatic properties, such natural molecules are of high interest to the pharmaceutical industry. In nature, these metabolites are often synthesized via secondary metabolic biosynthetic gene clusters that are silent under the typical culturing conditions. Among different techniques used to activate these silent gene clusters, co-culturing of "producer" species with specific "inducer" microbes is a particularly appealing approach due to its simplicity. Although several "inducer-producer" microbial consortia have been reported in the literature and hundreds of different secondary metabolites with attractive biopharmaceutical properties have been described as a result of co-cultivating inducer-producer consortia, less attention has been devoted to the understanding of the mechanisms and possible means of induction for production of secondary metabolites in co-cultures. This lack of understanding of fundamental biological functions and inter-species interactions significantly limits the diversity and yield of valuable compounds using biological engineering tools. In this review, we summarize and categorize the known physiological mechanisms of production of secondary metabolites in inducer-producer consortia, and then discuss approaches that could be exploited to optimize the discovery and production of secondary metabolites.
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Affiliation(s)
- Miroslav Gasparek
- Department of Engineering Science, University of Oxford, Parks Road, Oxford OX1 3PJ, United Kingdom.
| | - Harrison Steel
- Department of Engineering Science, University of Oxford, Parks Road, Oxford OX1 3PJ, United Kingdom
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2
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Jeeva P, Jayaprakash SR, Jayaraman G. Hyaluronic acid production is enhanced by harnessing the heme-induced respiration in recombinant Lactococcus lactis cultures. Biochem Eng J 2022. [DOI: 10.1016/j.bej.2022.108428] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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3
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Refactoring transcription factors for metabolic engineering. Biotechnol Adv 2022; 57:107935. [PMID: 35271945 DOI: 10.1016/j.biotechadv.2022.107935] [Citation(s) in RCA: 36] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2021] [Revised: 02/04/2022] [Accepted: 03/03/2022] [Indexed: 12/19/2022]
Abstract
Due to the ability to regulate target metabolic pathways globally and dynamically, metabolic regulation systems composed of transcription factors have been widely used in metabolic engineering and synthetic biology. This review introduced the categories, action principles, prediction strategies, and related databases of transcription factors. Then, the application of global transcription machinery engineering technology and the transcription factor-based biosensors and quorum sensing systems are overviewed. In addition, strategies for optimizing the transcriptional regulatory tools' performance by refactoring transcription factors are summarized. Finally, the current limitations and prospects of constructing various regulatory tools based on transcription factors are discussed. This review will provide theoretical guidance for the rational design and construction of transcription factor-based metabolic regulation systems.
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4
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Wang Y, Li Q, Tian P, Tan T. Charting the landscape of RNA polymerases to unleash their potential in strain improvement. Biotechnol Adv 2021; 54:107792. [PMID: 34216775 DOI: 10.1016/j.biotechadv.2021.107792] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2021] [Revised: 05/28/2021] [Accepted: 06/26/2021] [Indexed: 11/19/2022]
Abstract
One major mission of microbial cell factory is overproduction of desired chemicals. To this end, it is necessary to orchestrate enzymes that affect metabolic fluxes. However, only modification of a small number of enzymes in most cases cannot maximize desired metabolites, and global regulation is required. Of myriad enzymes influencing global regulation, RNA polymerase (RNAP) may be the most versatile enzyme in biological realm because it not only serves as the workhorse of central dogma but also participates in a plethora of biochemical events. In fact, recent years have witnessed extensive exploitation of RNAPs for phenotypic engineering. While a few impressive reviews showcase the structures and functionalities of RNAPs, this review not only summarizes the state-of-the-art advance in the structures of RNAPs but also points out their enormous potentials in metabolic engineering and synthetic biology. This review aims to provide valuable insights for strain improvement.
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Affiliation(s)
- Ye Wang
- Beijing Key Laboratory of Bioprocess, College of Life Science and Technology, Beijing University of Chemical Technology, Beijing 100029, PR China
| | - Qingyang Li
- School of Food Science and Engineering, South China University of Technology, Guangzhou 510641, PR China
| | - Pingfang Tian
- Beijing Key Laboratory of Bioprocess, College of Life Science and Technology, Beijing University of Chemical Technology, Beijing 100029, PR China.
| | - Tianwei Tan
- Beijing Key Laboratory of Bioprocess, College of Life Science and Technology, Beijing University of Chemical Technology, Beijing 100029, PR China
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5
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Biopolymer production by halotolerant bacteria isolated from Caatinga biome. Braz J Microbiol 2021; 52:547-559. [PMID: 33491139 DOI: 10.1007/s42770-021-00426-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2020] [Accepted: 01/06/2021] [Indexed: 12/21/2022] Open
Abstract
Saline environments are extreme habitats with a high diversity of microorganisms source of a myriad of biomolecules. These microorganisms are assigned as extremophiles recognized to be producers of new natural compounds, which can be synthesized by helping to survive under harshness and extreme conditions. In Brazil, in the saline and semi-arid region of Areia Branca (Caatinga biome), halotolerant bacteria (able to growth at high NaCl concentrations) were isolated from rhizosphere of native plants Blutaparon portulacoides and Spergularia sp. and their biopolymer production was studied. A total of 25 bacterial isolates were identified at genus level based on 16S rRNA gene sequence analysis. Isolates were mainly Gram-positive bacteria from Bacillaceae, Staphylococcaceae, Microbacteriaceae, and Bacillales XII incertae sedis families, affiliates to Bacillus, Staphylococcus, Curtobacterium, and Exiguobacterium genera, respectively. One of the Gram-negative isolates was identified as member of the Pseudomonadaceae family, genus Pseudomonas. All the identified strains were halotolerant bacteria with optimum growth at 0.6-2.0 M salt concentrations. Assays for biopolymer production showed that the halotolerant strains are a rich source of compounds as polyhydroxyalkanoates (PHA), biodegradable biopolymer, such as poly(3-hydroxybutyrate) (PHB) produced from low-cost substrates, and exopolysaccharides (EPS), such as hyaluronic acid (HA), metabolite of great interest to the cosmetic and pharmaceutical industry. Also, eight bacterial EPS extracts showed immunostimulatory activity, promising results that can be used in biomedical applications. Overall, our findings demonstrate that these biomolecules can be produced in culture medium with 0.6-2.0 M NaCl concentrations, relevant feature to avoid costly production processes. This is the first report of biopolymer-producing bacteria from a saline region of Caatinga biome that showed important biological activities.
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6
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Wang Y, Hu L, Huang H, Wang H, Zhang T, Chen J, Du G, Kang Z. Eliminating the capsule-like layer to promote glucose uptake for hyaluronan production by engineered Corynebacterium glutamicum. Nat Commun 2020; 11:3120. [PMID: 32561727 PMCID: PMC7305114 DOI: 10.1038/s41467-020-16962-7] [Citation(s) in RCA: 39] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2019] [Accepted: 06/01/2020] [Indexed: 02/06/2023] Open
Abstract
Hyaluronan is widely used in cosmetics and pharmaceutics. Development of robust and safe cell factories and cultivation approaches to efficiently produce hyaluronan is of many interests. Here, we describe the metabolic engineering of Corynebacterium glutamicum and application of a fermentation strategy to manufacture hyaluronan with different molecular weights. C. glutamicum is engineered by combinatorial overexpression of type I hyaluronan synthase, enzymes of intermediate metabolic pathways and attenuation of extracellular polysaccharide biosynthesis. The engineered strain produces 34.2 g L−1 hyaluronan in fed-batch cultures. We find secreted hyaluronan encapsulates C. glutamicum, changes its cell morphology and inhibits metabolism. Disruption of the encapsulation with leech hyaluronidase restores metabolism and leads to hyper hyaluronan productions of 74.1 g L−1. Meanwhile, the molecular weight of hyaluronan is also highly tunable. These results demonstrate combinatorial optimization of cell factories and the extracellular environment is efficacious and likely applicable for the production of other biopolymers. Bioproduction of hyaluronan needs increases in yield and greater diversity of the molecular weights. Here, the author increases hyaluronan production and diversifies the molecular weights through engineering the hyaluronan biosynthesis pathway and disruption of Corynebacterium glutamicum encapsulation caused by secreted hyaluronan.
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Affiliation(s)
- Yang Wang
- The Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry of Education, Jiangnan University, 214122, Wuxi, China.,The Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, 214122, Wuxi, China
| | - Litao Hu
- The Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry of Education, Jiangnan University, 214122, Wuxi, China.,The Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, 214122, Wuxi, China
| | - Hao Huang
- The Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, 214122, Wuxi, China
| | - Hao Wang
- The Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, 214122, Wuxi, China
| | | | - Jian Chen
- The Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry of Education, Jiangnan University, 214122, Wuxi, China.,The Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, 214122, Wuxi, China
| | - Guocheng Du
- The Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry of Education, Jiangnan University, 214122, Wuxi, China.,The Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, 214122, Wuxi, China
| | - Zhen Kang
- The Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry of Education, Jiangnan University, 214122, Wuxi, China. .,The Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, 214122, Wuxi, China.
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7
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Coussement P, Bauwens D, Peters G, Maertens J, De Mey M. Mapping and refactoring pathway control through metabolic and protein engineering: The hexosamine biosynthesis pathway. Biotechnol Adv 2020; 40:107512. [DOI: 10.1016/j.biotechadv.2020.107512] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2019] [Revised: 08/07/2019] [Accepted: 09/30/2019] [Indexed: 01/14/2023]
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8
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Woo JE, Seong HJ, Lee SY, Jang YS. Metabolic Engineering of Escherichia coli for the Production of Hyaluronic Acid From Glucose and Galactose. Front Bioeng Biotechnol 2019; 7:351. [PMID: 31824939 PMCID: PMC6881274 DOI: 10.3389/fbioe.2019.00351] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2019] [Accepted: 11/06/2019] [Indexed: 11/17/2022] Open
Abstract
Hyaluronic acid is a glycosaminoglycan biopolymer widely present throughout connective and epithelial tissue, and has been of great interest for medical and cosmetic applications. In the microbial production of hyaluronic acid, it has not been established to utilize galactose enabling to be converted to UDP-glucuronic acid, which is a precursor for hyaluronic acid biosynthesis. In this study, we engineered Escherichia coli to produce hyaluronic acid from glucose and galactose. The galactose-utilizing Leloir pathway was activated by knocking out the galR and galS genes encoding the transcriptional repressors. Also, the hasA gene from Streptococcus zooepidemicus was introduced for the expression of hyaluronic acid synthase. The consumption rates of glucose and galactose were modulated by knockout of the pfkA and zwf genes, which encode 6-phosphofructokinase I and glucose-6-phosphate dehydrogenase, respectively. Furthermore, the precursor biosynthesis pathway for hyaluronic acid production was manipulated by separately overexpressing the gene clusters galU-ugd and glmS-glmM-glmU, which enable the production of UDP-glucuronic acid and UDP-N-acetyl-glucosamine, respectively. Batch culture of the final engineered strain produced 29.98 mg/L of hyaluronic acid from glucose and galactose. As a proof of concept, this study demonstrated the production of hyaluronic acid from glucose and galactose in the engineered E. coli.
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Affiliation(s)
- Ji Eun Woo
- Department of Agricultural Chemistry and Food Science Technology, Division of Applied Life Science (BK21 Plus Program), Institute of Agriculture & Life Science (IALS), Gyeongsang National University, Jinju, South Korea
| | - Hyeon Jeong Seong
- Department of Agricultural Chemistry and Food Science Technology, Division of Applied Life Science (BK21 Plus Program), Institute of Agriculture & Life Science (IALS), Gyeongsang National University, Jinju, South Korea
| | - Sang Yup Lee
- Department of Chemical and Biomolecular Engineering (BK21 Plus Program), BioProcess Engineering Research Center, Center for Systems and Synthetic Biotechnology, Institute for the BioCentury, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, South Korea
| | - Yu-Sin Jang
- Department of Agricultural Chemistry and Food Science Technology, Division of Applied Life Science (BK21 Plus Program), Institute of Agriculture & Life Science (IALS), Gyeongsang National University, Jinju, South Korea
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9
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Niu FX, Huang YB, Ji LN, Liu JZ. Genomic and transcriptional changes in response to pinene tolerance and overproduction in evolved Escherichia coli. Synth Syst Biotechnol 2019; 4:113-119. [PMID: 31198860 PMCID: PMC6556621 DOI: 10.1016/j.synbio.2019.05.001] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2019] [Revised: 05/19/2019] [Accepted: 05/19/2019] [Indexed: 01/01/2023] Open
Abstract
α-Pinene is an important monoterpene, which is widely used as a flavoring agent and in fragrances, pharmaceuticals and biofuels. Although an evolved strain Escherichia coli YZFP, which had higher tolerance to pinene and titer, has been successfully used to produce high levels of pinene, the pinene titer is much lower than that of hemiterpene (isoprene) and sesquiterpenes (farnesene) to date. Moreover, the overall cellular physiological and metabolic changes caused by higher tolerance to pinene and overproduction of pinene remains unclear. To reveal the mechanism of Escherichia coli YZFP with the higher tolerance to pinene and titer, a comparative genomics and transcriptional level analyses combining with CRISPR activation (CRISPRa) and interference (CRISPRi) were carried out. The results show that the tolerance to pinene and the overproduction of pinene in E. coli may be associated with: 1) the mutations of the DXP pathway genes, the rpoA and some membrane protein genes, and their upregulations of transcription levels; and 2) the mutations of some genes and their downregulation of transcriptional levels. These comparative omics analyses provided some genetic modification strategies to further improve pinene production. Overexpression of the mutated cbpA, tabA, pitA, rpoA, sufBCDS, mutS, ispH, oppF, dusB, dnaK, dxs, dxr and flgFGH genes further improved pinene production. This study also demonstrated that combining comparative omics analysis with CRISPRa and CRISPRi is an efficient technology to quickly find a new metabolic engineering strategy. A genomics and transcriptional level analyses combining with CRISPRa and CRISPRi was carried out. The mechanism of the tolerance to pinene and overproduction of pinene was obtained. Some target genes difficultly found by rational analysis were identified. Combining comparative omics analysis with CRISPRa/i is an efficient technology for metabolic engineering.
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Affiliation(s)
- Fu-Xing Niu
- Institute of Synthetic Biology, MOE Key Laboratory of Bioinorganic and Synthetic Chemistry, School of Life Sciences, Sun Yat-Sen University, Guangzhou 510275, China
| | - Yuan-Bin Huang
- Institute of Synthetic Biology, MOE Key Laboratory of Bioinorganic and Synthetic Chemistry, School of Life Sciences, Sun Yat-Sen University, Guangzhou 510275, China
| | - Liang-Nian Ji
- Institute of Synthetic Biology, MOE Key Laboratory of Bioinorganic and Synthetic Chemistry, School of Life Sciences, Sun Yat-Sen University, Guangzhou 510275, China
| | - Jian-Zhong Liu
- Institute of Synthetic Biology, MOE Key Laboratory of Bioinorganic and Synthetic Chemistry, School of Life Sciences, Sun Yat-Sen University, Guangzhou 510275, China
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10
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McKenna R, Lombana TN, Yamada M, Mukhyala K, Veeravalli K. Engineered sigma factors increase full-length antibody expression in Escherichia coli. Metab Eng 2019; 52:315-323. [DOI: 10.1016/j.ymben.2018.12.009] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2018] [Revised: 12/26/2018] [Accepted: 12/27/2018] [Indexed: 12/24/2022]
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11
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Zhou Z, Li Q, Huang H, Wang H, Wang Y, Du G, Chen J, Kang Z. A microbial-enzymatic strategy for producing chondroitin sulfate glycosaminoglycans. Biotechnol Bioeng 2018; 115:1561-1570. [PMID: 29484646 DOI: 10.1002/bit.26577] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2017] [Revised: 02/14/2018] [Accepted: 02/18/2018] [Indexed: 01/11/2023]
Abstract
Chondroitin sulfate has been widely used in both medical and clinical applications. Commercial chondroitin sulfate has been mainly acquired from animal tissue extraction. Here we report a new two-step biological strategy for producing chondroitin sulfate A and chondroitin sulfate C. First, the chondroitin biosynthesis pathway in a recombinant Bacillus subtilis strain using sucrose as carbon source was systematically optimized and the titer of chondroitin was significantly enhanced to 7.15 g/L. Then, specific sulfation transformation systems were successfully constructed and optimized by combining the purified aryl sulfotransferase IV (ASST IV), chondroitin 4-sulfotransferase (C4ST) and chondroitin 6-sulfotransferase (C6ST). Chondroitin sulfate A and C were enzymatically transformed from chondroitin at conversion rates of 98% and 96%, respectively. The present biological strategy has great potential to be scaled up for biosynthesis of chondroitin sulfate A and C from cheap carbon sources.
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Affiliation(s)
- Zhengxiong Zhou
- The Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi, China
- The Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi, China
| | - Qing Li
- The Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi, China
- The Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi, China
| | - Hao Huang
- The Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi, China
- The Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi, China
| | - Hao Wang
- The Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi, China
- The Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi, China
| | - Yang Wang
- The Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi, China
- The Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi, China
| | - Guocheng Du
- The Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi, China
- The Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi, China
| | - Jian Chen
- The Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi, China
- Synergetic Innovation Center of Food Safety and Nutrition, Jiangnan University, Wuxi, Jiangsu, China
| | - Zhen Kang
- The Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi, China
- The Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi, China
- Synergetic Innovation Center of Food Safety and Nutrition, Jiangnan University, Wuxi, Jiangsu, China
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12
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Evolutionary engineering of industrial microorganisms-strategies and applications. Appl Microbiol Biotechnol 2018; 102:4615-4627. [DOI: 10.1007/s00253-018-8937-1] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2017] [Revised: 03/13/2018] [Accepted: 03/13/2018] [Indexed: 10/17/2022]
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13
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Dostálová H, Holátko J, Busche T, Rucká L, Rapoport A, Halada P, Nešvera J, Kalinowski J, Pátek M. Assignment of sigma factors of RNA polymerase to promoters in Corynebacterium glutamicum. AMB Express 2017. [PMID: 28651382 PMCID: PMC5483222 DOI: 10.1186/s13568-017-0436-8] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Corynebacterium glutamicum is an important industrial producer of various amino acids and other metabolites. The C. glutamicum genome encodes seven sigma subunits (factors) of RNA polymerase: the primary sigma factor SigA (σA), the primary-like σB and five alternative sigma factors (σC, σD, σE, σH and σM). We have developed in vitro and in vivo methods to assign particular sigma factors to individual promoters of different classes. In vitro transcription assays and measurements of promoter activity using the overexpression of a single sigma factor gene and the transcriptional fusion of the promoter to the gfpuv reporter gene enabled us to reliably define the sigma factor dependency of promoters. To document the strengths of these methods, we tested examples of respective promoters for each C. glutamicum sigma factor. Promoters of the rshA (anti-sigma for σH) and trxB1 (thioredoxin) genes were found to be σH-dependent, whereas the promoter of the sigB gene (sigma factor σB) was σE- and σH-dependent. It was confirmed that the promoter of the cg2556 gene (iron-regulated membrane protein) is σC-dependent as suggested recently by other authors. The promoter of cmt1 (trehalose corynemycolyl transferase) was found to be clearly σD-dependent. No σM-dependent promoter was identified. The typical housekeeping promoter P2sigA (sigma factor σA) was proven to be σA-dependent but also recognized by σB. Similarly, the promoter of fba (fructose-1,6-bisphosphate aldolase) was confirmed to be σB-dependent but also functional with σA. The study provided demonstrations of the broad applicability of the developed methods and produced original data on the analyzed promoters.
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14
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Cheng F, Luozhong S, Guo Z, Yu H, Stephanopoulos G. Enhanced Biosynthesis of Hyaluronic Acid Using Engineered Corynebacterium glutamicum Via Metabolic Pathway Regulation. Biotechnol J 2017; 12. [PMID: 28869338 DOI: 10.1002/biot.201700191] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2017] [Revised: 08/27/2017] [Indexed: 11/07/2022]
Abstract
Hyaluronic acid (HA) is a polysaccharide used in many industries such as medicine, surgery, cosmetics, and food. To avoid potential pathogenicity caused by its native producer, Streptococcus, efforts have been made to create a recombinant host for HA production. In this work, a GRAS (generally recognized as safe) strain, Corynebacterium glutamicum, is engineered for enhanced biosynthesis of HA via metabolic pathway regulation. Five enzymes (HasA-HasE) involved in the HA biosynthetic pathway are highlighted, and eight diverse operon combinations, including HasA, HasAB, HasAC, HasAD, HasAE, HasABC, HasABD, and HasABE, are compared. HasAB and HasABC are found to be optimal for HA biosynthesis in C. glutamicum. To meet the energy demand for HA synthesis, the metabolic pathway that produces lactate is blocked by knocking out the lactate dehydrogenase (LDH) gene using single crossover homologous recombination. Engineered C. glutamicum/Δldh-AB is superior and had a significantly higher HA titer than C. glutamicum/Δldh-ABC. Batch and fed-batch cultures of C. glutamicum/Δldh-AB are performed in a 5-L fermenter. Using glucose feeding, the maximum HA titer reached 21.6 g L-1 , more than threefolds of that of the wild-type Streptococcus. This work provides an efficient, safe, and novel recombinant HA producer, C. glutamicum/Δldh-AB, via metabolic pathway regulation.
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Affiliation(s)
- Fangyu Cheng
- Key Laboratory for Industrial Biocatalysis of the Ministry of Education, Department of Chemical Engineering, Tsinghua University, Beijing 100084, P. R. China
- Center for Synthetic and Systems Biology, Tsinghua University, Beijing 100084, P. R. China
| | - Sijin Luozhong
- Key Laboratory for Industrial Biocatalysis of the Ministry of Education, Department of Chemical Engineering, Tsinghua University, Beijing 100084, P. R. China
- Center for Synthetic and Systems Biology, Tsinghua University, Beijing 100084, P. R. China
| | - Zhigang Guo
- Key Laboratory for Industrial Biocatalysis of the Ministry of Education, Department of Chemical Engineering, Tsinghua University, Beijing 100084, P. R. China
| | - Huimin Yu
- Key Laboratory for Industrial Biocatalysis of the Ministry of Education, Department of Chemical Engineering, Tsinghua University, Beijing 100084, P. R. China
- Center for Synthetic and Systems Biology, Tsinghua University, Beijing 100084, P. R. China
| | - Gregory Stephanopoulos
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
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15
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Enabling tools for high-throughput detection of metabolites: Metabolic engineering and directed evolution applications. Biotechnol Adv 2017; 35:950-970. [PMID: 28723577 DOI: 10.1016/j.biotechadv.2017.07.005] [Citation(s) in RCA: 79] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2017] [Revised: 06/07/2017] [Accepted: 07/11/2017] [Indexed: 12/21/2022]
Abstract
Within the Design-Build-Test Cycle for strain engineering, rapid product detection and selection strategies remain challenging and limit overall throughput. Here we summarize a wide variety of modalities that transduce chemical concentrations into easily measured absorbance, luminescence, and fluorescence signals. Specifically, we cover protein-based biosensors (including transcription factors), nucleic acid-based biosensors, coupled enzyme reactions, bioorthogonal chemistry, and fluorescent and chromogenic dyes and substrates as modalities for detection. We focus on the use of these methods for strain engineering and enzyme discovery and conclude with remarks on the current and future state of biosensor development for application in the metabolic engineering field.
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16
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Liu Y, Zhuang Y, Ding D, Xu Y, Sun J, Zhang D. Biosensor-Based Evolution and Elucidation of a Biosynthetic Pathway in Escherichia coli. ACS Synth Biol 2017; 6:837-848. [PMID: 28121425 DOI: 10.1021/acssynbio.6b00328] [Citation(s) in RCA: 50] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The successful evolution of metabolite-producing microbes requires a high-throughput screening method to obtain the desired properties within a short time. In this study, we developed a transcription-factor-driven device that combines a metabolite-responsive element and a selection module. This device was able to specifically sense intracellular l-phenylalanine (l-Phe) and convert this signal into an observable phenotype. Applying this device, we successfully improved l-Phe production by screening hyperproducing phenotypes from a ribonucleotide binding site library and a random mutagenesis library. In addition, several site mutations introduced by random mutagenesis were identified and elucidated to facilitate the improvement of l-Phe production. Our results present a paradigm for screening of compounds that are not easily observable to raise the yield of targeted compounds from a large candidate library. This approach may guide further applications in rewiring metabolic circuits and facilitate the directed evolution of recombinant strains.
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Affiliation(s)
- Yongfei Liu
- Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin 300308, China
- Key
Laboratory of Systems Microbial Biotechnology, Chinese Academy of Sciences, Tianjin 300308, China
| | - Yinyin Zhuang
- Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin 300308, China
| | - Dongqin Ding
- Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin 300308, China
- Key
Laboratory of Systems Microbial Biotechnology, Chinese Academy of Sciences, Tianjin 300308, China
| | - Yiran Xu
- Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin 300308, China
| | - Jibin Sun
- Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin 300308, China
- Key
Laboratory of Systems Microbial Biotechnology, Chinese Academy of Sciences, Tianjin 300308, China
| | - Dawei Zhang
- Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin 300308, China
- Key
Laboratory of Systems Microbial Biotechnology, Chinese Academy of Sciences, Tianjin 300308, China
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Becker J, Wittmann C. Systems metabolic engineering of Escherichia coli for the heterologous production of high value molecules — a veteran at new shores. Curr Opin Biotechnol 2016; 42:178-188. [DOI: 10.1016/j.copbio.2016.05.004] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2016] [Revised: 05/19/2016] [Accepted: 05/21/2016] [Indexed: 12/13/2022]
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Guo Y, Dong Y, Hong X, Pang X, Chen D, Chen X. Directed Evolution of Dunaliella salina Ds-26-16 and Salt-Tolerant Response in Escherichia coli. Int J Mol Sci 2016; 17:ijms17111813. [PMID: 27801872 PMCID: PMC5133814 DOI: 10.3390/ijms17111813] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2016] [Revised: 10/17/2016] [Accepted: 10/25/2016] [Indexed: 12/02/2022] Open
Abstract
Identification and evolution of salt tolerant genes are crucial steps in developing salt tolerant crops or microorganisms using biotechnology. Ds-26-16, a salt tolerant gene that was isolated from Dunaliella salina, encodes a transcription factor that can confer salt tolerance to a number of organisms including Escherichia coli (E. coli), Haematococcus pluvialis and tobacco. To further improve its salt tolerance, a random mutagenesis library was constructed using deoxyinosine triphosphate-mediated error-prone PCR technology, and then screened using an E. coli expression system that is based on its broad-spectrum salt tolerance. Seven variants with enhanced salt tolerance were obtained. Variant EP-5 that contained mutation S32P showed the most improvement with the E. coli transformant enduring salt concentrations up to 1.54 M, in comparison with 1.03 M for the wild type gene. Besides, Ds-26-16 and EP-5 also conferred E. coli transformant tolerance to freezing, cold, heat, Cu2+ and alkaline. Homology modeling revealed that mutation S32P in EP-5 caused the conformational change of N- and C-terminal α-helixes. Expression of Ds-26-16 and EP-5 maintained normal cellular morphology, increased the intracellular antioxidant enzymatic activity, reduced malondialdehyde content, and stimulated Nitric Oxide synthesis, thus enhancing salt tolerance to E. coli transformants.
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Affiliation(s)
- Yuan Guo
- Department of Biochemistry and Molecular Biology, College of Life Sciences, Nankai University, No. 94 Weijin Rd., Tianjin 300071, China.
| | - Yanping Dong
- Department of Biochemistry and Molecular Biology, College of Life Sciences, Nankai University, No. 94 Weijin Rd., Tianjin 300071, China.
| | - Xiao Hong
- Department of Genetics and Cell Biology, College of Life Sciences, Nankai University, No. 94 Weijin Rd., Tianjin 300071, China.
| | - Xiaonan Pang
- Department of Genetics and Cell Biology, College of Life Sciences, Nankai University, No. 94 Weijin Rd., Tianjin 300071, China.
| | - Defu Chen
- Department of Genetics and Cell Biology, College of Life Sciences, Nankai University, No. 94 Weijin Rd., Tianjin 300071, China.
| | - Xiwen Chen
- Department of Biochemistry and Molecular Biology, College of Life Sciences, Nankai University, No. 94 Weijin Rd., Tianjin 300071, China.
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de Oliveira JD, Carvalho LS, Gomes AMV, Queiroz LR, Magalhães BS, Parachin NS. Genetic basis for hyper production of hyaluronic acid in natural and engineered microorganisms. Microb Cell Fact 2016; 15:119. [PMID: 27370777 PMCID: PMC4930576 DOI: 10.1186/s12934-016-0517-4] [Citation(s) in RCA: 67] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2016] [Accepted: 06/22/2016] [Indexed: 11/10/2022] Open
Abstract
Hyaluronic acid, or HA, is a rigid and linear biopolymer belonging to the class of the glycosaminoglycans, and composed of repeating units of the monosaccharides glucuronic acid and N-acetylglucosamine. HA has multiple important functions in the human body, due to its properties such as bio-compatibility, lubricity and hydrophilicity, it is widely applied in the biomedical, food, health and cosmetic fields. The growing interest in this molecule has motivated the discovery of new ways of obtaining it. Traditionally, HA has been extracted from rooster comb-like animal tissues. However, due to legislation laws HA is now being produced by bacterial fermentation using Streptococcus zooepidemicus, a natural producer of HA, despite it being a pathogenic microorganism. With the expansion of new genetic engineering technologies, the use of organisms that are non-natural producers of HA has also made it possible to obtain such a polymer. Most of the published reviews have focused on HA formulation and its effects on different body tissues, whereas very few of them describe the microbial basis of HA production. Therefore, for the first time this review has compiled the molecular and genetic bases for natural HA production in microorganisms together with the main strategies employed for heterologous production of HA.
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Affiliation(s)
- Juliana Davies de Oliveira
- Pós-Graduação em Ciências Genômicas e Biotecnologia, Universidade Católica de Brasília, Brasília, DF, CEP 70.790-160, Brazil
| | - Lucas Silva Carvalho
- Integra Bioprocessos e Análises, Campus Universitário Darcy Ribeiro, Edifício CDT, Sala AT-36/37, Brasília, DF, CEP 70.904-970, Brazil
| | - Antônio Milton Vieira Gomes
- Grupo de Engenharia Metabólica Aplicada a Bioprocessos, Instituto de Ciências Biológicas, Universidade de Brasília, Brasília, DF, CEP 70.790-900, Brazil
| | - Lúcio Rezende Queiroz
- Grupo de Engenharia Metabólica Aplicada a Bioprocessos, Instituto de Ciências Biológicas, Universidade de Brasília, Brasília, DF, CEP 70.790-900, Brazil
| | - Beatriz Simas Magalhães
- Pós-Graduação em Ciências Genômicas e Biotecnologia, Universidade Católica de Brasília, Brasília, DF, CEP 70.790-160, Brazil.,Integra Bioprocessos e Análises, Campus Universitário Darcy Ribeiro, Edifício CDT, Sala AT-36/37, Brasília, DF, CEP 70.904-970, Brazil
| | - Nádia Skorupa Parachin
- Grupo de Engenharia Metabólica Aplicada a Bioprocessos, Instituto de Ciências Biológicas, Universidade de Brasília, Brasília, DF, CEP 70.790-900, Brazil.
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Cheng F, Gong Q, Yu H, Stephanopoulos G. High-titer biosynthesis of hyaluronic acid by recombinantCorynebacterium glutamicum. Biotechnol J 2016; 11:574-84. [DOI: 10.1002/biot.201500404] [Citation(s) in RCA: 49] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2015] [Revised: 10/09/2015] [Accepted: 12/18/2015] [Indexed: 12/19/2022]
Affiliation(s)
- Fangyu Cheng
- Key Laboratory for Industrial Biocatalysis of the Ministry of Education, Department of Chemical Engineering, Tsinghua University; Beijing China
| | - Qianying Gong
- College of Life Science and Technology, Beijing University of Chemical Technology; Beijing China
| | - Huimin Yu
- Key Laboratory for Industrial Biocatalysis of the Ministry of Education, Department of Chemical Engineering, Tsinghua University; Beijing China
| | - Gregory Stephanopoulos
- Department of Chemical Engineering, Massachusetts Institute of Technology; Cambridge MA USA
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Building cellular pathways and programs enabled by the genetic diversity of allo-genomes and meta-genomes. Curr Opin Biotechnol 2015; 36:16-31. [DOI: 10.1016/j.copbio.2015.08.005] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2015] [Revised: 08/06/2015] [Accepted: 08/09/2015] [Indexed: 12/21/2022]
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22
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Zhang F, Qian X, Si H, Xu G, Han R, Ni Y. Significantly improved solvent tolerance of Escherichia coli by global transcription machinery engineering. Microb Cell Fact 2015; 14:175. [PMID: 26542360 PMCID: PMC4635540 DOI: 10.1186/s12934-015-0368-4] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2015] [Accepted: 09/26/2015] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Escherichia coli has emerged as a promising platform microorganism to produce biofuels and fine chemicals of industrial interests. Certain obstacles however remain to be overcome, among which organic-solvent tolerance is a crucial one. RESULTS We used global transcription machinery engineering (gTME) to improve the organic-solvent tolerance (OST) of E. coli JM109. A mutant library of σ(70) encoded by rpoD was screened under cyclohexane pressure. E. coli JM109 strain harboring σ(70) mutant C9 was identified with capability of tolerating 69 % cyclohexane. The rpoD mutant contains three amino-acid substitutes and a stop-codon mutation, resulting a truncated sequence containing regions σ(1.1) and σ(1.2). Total protein difference produced by E. coli JM109 strain harboring C9 was examined with 2D-PAGE, and 204 high-abundant proteins showed over twofold variation under different solvent stress. CONCLUSIONS Our results show that several genes (gapA, sdhB, pepB and dppA) play critical roles in enhanced solvent tolerance of E. coli, mainly involving in maintaining higher intracellular energy level under solvent stress. Global transcription machinery engineering is therefore a feasible and efficient approach for engineering strain with enhanced OST-phenotype.
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Affiliation(s)
- Fa Zhang
- The Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, 214122, Wuxi, Jiangsu, China.
| | - Xiaohong Qian
- The Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, 214122, Wuxi, Jiangsu, China.
| | - Haiming Si
- The Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, 214122, Wuxi, Jiangsu, China.
| | - Guochao Xu
- The Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, 214122, Wuxi, Jiangsu, China.
| | - Ruizhi Han
- The Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, 214122, Wuxi, Jiangsu, China.
| | - Ye Ni
- The Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, 214122, Wuxi, Jiangsu, China.
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Liu W, Jiang R. Combinatorial and high-throughput screening approaches for strain engineering. Appl Microbiol Biotechnol 2015; 99:2093-104. [DOI: 10.1007/s00253-015-6400-0] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2014] [Revised: 01/09/2015] [Accepted: 01/10/2015] [Indexed: 12/31/2022]
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24
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Tripathi L, Zhang Y, Lin Z. Bacterial sigma factors as targets for engineered or synthetic transcriptional control. Front Bioeng Biotechnol 2014; 2:33. [PMID: 25232540 PMCID: PMC4153023 DOI: 10.3389/fbioe.2014.00033] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2014] [Accepted: 08/20/2014] [Indexed: 11/20/2022] Open
Abstract
Sigma (σ) factors are the predominant constituents of transcription regulation in bacteria. σ Factors recruit the core RNA polymerase to recognize promoters with specific DNA sequences. Recently, engineering of transcriptional regulators has become a significant tool for strain engineering. The present review summarizes the recent advances in σ factor based engineering or synthetic design. The manipulation of σ factors presents insights into the bacterial stress tolerance and metabolite productivity. We envision more synthetic design based on σ factors that can be used to tune the regulatory network of bacteria.
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Affiliation(s)
- Lakshmi Tripathi
- Department of Chemical Engineering, Tsinghua University , Beijing , China
| | - Yan Zhang
- Department of Chemical Engineering, Tsinghua University , Beijing , China
| | - Zhanglin Lin
- Department of Chemical Engineering, Tsinghua University , Beijing , China
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Liebl W, Angelov A, Juergensen J, Chow J, Loeschcke A, Drepper T, Classen T, Pietruszka J, Ehrenreich A, Streit WR, Jaeger KE. Alternative hosts for functional (meta)genome analysis. Appl Microbiol Biotechnol 2014; 98:8099-109. [PMID: 25091044 DOI: 10.1007/s00253-014-5961-7] [Citation(s) in RCA: 60] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2014] [Revised: 07/14/2014] [Accepted: 07/15/2014] [Indexed: 11/25/2022]
Abstract
Microorganisms are ubiquitous on earth, often forming complex microbial communities in numerous different habitats. Most of these organisms cannot be readily cultivated in the laboratory using standard media and growth conditions. However, it is possible to gain access to the vast genetic, enzymatic, and metabolic diversity present in these microbial communities using cultivation-independent approaches such as sequence- or function-based metagenomics. Function-based analysis is dependent on heterologous expression of metagenomic libraries in a genetically amenable cloning and expression host. To date, Escherichia coli is used in most cases; however, this has the drawback that many genes from heterologous genomes and complex metagenomes are expressed in E. coli either at very low levels or not at all. This review emphasizes the importance of establishing alternative microbial expression systems consisting of different genera and species as well as customized strains and vectors optimized for heterologous expression of membrane proteins, multigene clusters encoding protein complexes or entire metabolic pathways. The use of alternative host-vector systems will complement current metagenomic screening efforts and expand the yield of novel biocatalysts, metabolic pathways, and useful metabolites to be identified from environmental samples.
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Affiliation(s)
- Wolfgang Liebl
- Lehrstuhl für Mikrobiologie, Technische Universität München, Emil-Ramann-Str. 4, 85654, Freising, Germany,
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Cress BF, Englaender JA, He W, Kasper D, Linhardt RJ, Koffas MAG. Masquerading microbial pathogens: capsular polysaccharides mimic host-tissue molecules. FEMS Microbiol Rev 2014; 38:660-97. [PMID: 24372337 PMCID: PMC4120193 DOI: 10.1111/1574-6976.12056] [Citation(s) in RCA: 163] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2013] [Revised: 10/16/2013] [Accepted: 12/19/2013] [Indexed: 11/27/2022] Open
Abstract
The increasing prevalence of antibiotic-resistant bacteria portends an impending postantibiotic age, characterized by diminishing efficacy of common antibiotics and routine application of multifaceted, complementary therapeutic approaches to treat bacterial infections, particularly multidrug-resistant organisms. The first line of defense for most bacterial pathogens consists of a physical and immunologic barrier known as the capsule, commonly composed of a viscous layer of carbohydrates that are covalently bound to the cell wall in Gram-positive bacteria or often to lipids of the outer membrane in many Gram-negative bacteria. Bacterial capsular polysaccharides are a diverse class of high molecular weight polysaccharides contributing to virulence of many human pathogens in the gut, respiratory tree, urinary tract, and other host tissues, by hiding cell surface components that might otherwise elicit host immune response. This review highlights capsular polysaccharides that are structurally identical or similar to polysaccharides found in mammalian tissues, including polysialic acid and glycosaminoglycan capsules hyaluronan, heparosan, and chondroitin. Such nonimmunogenic coatings render pathogens insensitive to certain immune responses, effectively increasing residence time in host tissues and enabling pathologically relevant population densities to be reached. Biosynthetic pathways and capsular involvement in immune system evasion are described, providing a basis for potential therapies aimed at supplementing or replacing antibiotic treatment.
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Affiliation(s)
- Brady F Cress
- Department of Chemical and Biological Engineering, Center for Biotechnology and Interdisciplinary Studies, Rensselaer Polytechnic Institute, Troy, NY, USA
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27
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Wang H, Yang L, Wu K, Li G. Rational selection and engineering of exogenous principal sigma factor (σ(HrdB)) to increase teicoplanin production in an industrial strain of Actinoplanes teichomyceticus. Microb Cell Fact 2014; 13:10. [PMID: 24428890 PMCID: PMC3897980 DOI: 10.1186/1475-2859-13-10] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2013] [Accepted: 01/09/2014] [Indexed: 11/13/2022] Open
Abstract
Background Transcriptional engineering has presented a strong ability of phenotypic improvement in microorganisms. However, it could not be directly applied to Actinoplanes teichomyceticus L-27 because of the paucity of endogenous transcription factors in the strain. In this study, exogenous transcription factors were rationally selected and transcriptional engineering was carried out to increase the productivity of teicoplanin in L-27. Results It was illuminated that the σHrdB molecules shared strong similarity of amino acid sequences among some genera of actinomycetes. Combining this advantage with the ability of transcriptional engineering, exogenous sigma factor σHrdB molecules were rationally selected and engineered to improve L-27. hrdB genes from Actinoplanes missouriensis 431, Micromonospora aurantiaca ATCC 27029 and Salinispora arenicola CNS-205 were selected based on molecular evolutionary analysis. Random mutagenesis, DNA shuffling and point mutation were subsequently performed to generate diversified mutants. A recombinant was identified through screening program, yielding 5.3 mg/ml of teicoplanin, over 2-fold compared to that of L-27. More significantly, the engineered strain presented a good performance in 500-l pilot scale fermentation, which meant its valuable potential application in industry. Conclusions Through rational selection and engineering of exogenous transcriptional factor, we have extended the application of transcriptional engineering. To our knowledge, it is the first time to focus on the related issue. In addition, possessing the advantage of efficient metabolic perturbation in transcription level, this strategy could be useful in analyzing metabolic and physiological mechanisms of strains, especially those with the only information on taxonomy.
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Affiliation(s)
| | - Liu Yang
- School of Food and Bioengineering, Qilu University of Technology, Jinan 250353, PR China.
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Marcheschi RJ, Gronenberg LS, Liao JC. Protein engineering for metabolic engineering: current and next-generation tools. Biotechnol J 2013; 8:545-55. [PMID: 23589443 DOI: 10.1002/biot.201200371] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2012] [Revised: 03/07/2013] [Accepted: 03/20/2013] [Indexed: 11/10/2022]
Abstract
Protein engineering in the context of metabolic engineering is increasingly important to the field of industrial biotechnology. As the demand for biologically produced food, fuels, chemicals, food additives, and pharmaceuticals continues to grow, the ability to design and modify proteins to accomplish new functions will be required to meet the high productivity demands for the metabolism of engineered organisms. We review advances in selecting, modeling, and engineering proteins to improve or alter their activity. Some of the methods have only recently been developed for general use and are just beginning to find greater application in the metabolic engineering community. We also discuss methods of generating random and targeted diversity in proteins to generate mutant libraries for analysis. Recent uses of these techniques to alter cofactor use; produce non-natural amino acids, alcohols, and carboxylic acids; and alter organism phenotypes are presented and discussed as examples of the successful engineering of proteins for metabolic engineering purposes.
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Affiliation(s)
- Ryan J Marcheschi
- Department of Chemical and Biomolecular Engineering, University of California, Los Angeles, CA, USA
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29
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Skretas G, Kolisis FN. Combinatorial approaches for inverse metabolic engineering applications. Comput Struct Biotechnol J 2013; 3:e201210021. [PMID: 24688681 PMCID: PMC3962077 DOI: 10.5936/csbj.201210021] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2012] [Revised: 02/11/2013] [Accepted: 02/17/2013] [Indexed: 11/22/2022] Open
Abstract
Traditional metabolic engineering analyzes biosynthetic and physiological pathways, identifies bottlenecks, and makes targeted genetic modifications with the ultimate goal of increasing the production of high-value products in living cells. Such efforts have led to the development of a variety of organisms with industrially relevant properties. However, there are a number of cellular phenotypes important for research and the industry for which the rational selection of cellular targets for modification is not easy or possible. In these cases, strain engineering can be alternatively carried out using “inverse metabolic engineering”, an approach that first generates genetic diversity by subjecting a population of cells to a particular mutagenic process, and then utilizes genetic screens or selections to identify the clones exhibiting the desired phenotype. Given the availability of an appropriate screen for a particular property, the success of inverse metabolic engineering efforts usually depends on the level and quality of genetic diversity which can be generated. Here, we review classic and recently developed combinatorial approaches for creating such genetic diversity and discuss the use of these methodologies in inverse metabolic engineering applications.
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Affiliation(s)
- Georgios Skretas
- Institute of Biology, Medicinal Chemistry and Biotechnology, National Hellenic Research Foundation, Athens, Greece
| | - Fragiskos N Kolisis
- Biotechnology Laboratory, School of Chemical Engineering, National Technical University of Athens - Zografou Campus, Athens, Greece
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30
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McKee AE, Rutherford BJ, Chivian DC, Baidoo EK, Juminaga D, Kuo D, Benke PI, Dietrich JA, Ma SM, Arkin AP, Petzold CJ, Adams PD, Keasling JD, Chhabra SR. Manipulation of the carbon storage regulator system for metabolite remodeling and biofuel production in Escherichia coli. Microb Cell Fact 2012; 11:79. [PMID: 22694848 PMCID: PMC3460784 DOI: 10.1186/1475-2859-11-79] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2012] [Accepted: 05/24/2012] [Indexed: 12/17/2022] Open
Abstract
Background Microbial engineering strategies that elicit global metabolic perturbations have the capacity to increase organism robustness for targeted metabolite production. In particular, perturbations to regulators of cellular systems that impact glycolysis and amino acid production while simultaneously decreasing fermentation by-products such as acetate and CO2 make ideal targets. Intriguingly, perturbation of the Carbon Storage Regulator (Csr) system has been previously implicated in large changes in central carbon metabolism in E. coli. Therefore, we hypothesized that perturbation of the Csr system through the CsrA-CsrB ribonucleoprotein complex might increase production of biofuels and their intermediates from heterologous pathways. Results We engaged the CsrA-CsrB ribonucleoprotein complex of E. coli via overexpression of CsrB. CsrB is a 350-nucleotide non-coding RNA that antagonizes CsrA, an RNA-binding protein that regulates translation of specific mRNA targets. By using shotgun proteomics and targeted metabolomics we established that elevation of CsrB levels leads to alterations in metabolite and protein levels in glycolysis, the TCA cycle and amino acid levels. Consequently, we show that such changes can be suitably applied to improve the production of desired compounds through the native fatty acid and heterologous n-butanol and isoprenoid pathways by up to two-fold. We also observed concomitant decreases in undesirable fermentation by-products such as acetate and CO2. Conclusions We have demonstrated that simple engineering of the RNA-based Csr global regulatory system constitutes a novel approach to obtaining pathway-independent improvements within engineered hosts. Additionally, since Csr is conserved across most prokaryotic species, this approach may also be amenable to a wide variety of production hosts.
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31
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Gustafsson C, Minshull J, Govindarajan S, Ness J, Villalobos A, Welch M. Engineering genes for predictable protein expression. Protein Expr Purif 2012; 83:37-46. [PMID: 22425659 DOI: 10.1016/j.pep.2012.02.013] [Citation(s) in RCA: 112] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2011] [Revised: 02/27/2012] [Accepted: 02/28/2012] [Indexed: 10/28/2022]
Abstract
The DNA sequence used to encode a polypeptide can have dramatic effects on its expression. Lack of readily available tools has until recently inhibited meaningful experimental investigation of this phenomenon. Advances in synthetic biology and the application of modern engineering approaches now provide the tools for systematic analysis of the sequence variables affecting heterologous expression of recombinant proteins. We here discuss how these new tools are being applied and how they circumvent the constraints of previous approaches, highlighting some of the surprising and promising results emerging from the developing field of gene engineering.
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32
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DeAngelis PL. Glycosaminoglycan polysaccharide biosynthesis and production: today and tomorrow. Appl Microbiol Biotechnol 2012; 94:295-305. [PMID: 22391966 DOI: 10.1007/s00253-011-3801-6] [Citation(s) in RCA: 96] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2011] [Revised: 11/29/2011] [Accepted: 12/01/2011] [Indexed: 10/28/2022]
Abstract
Glycosaminoglycans [GAGs] are essential heteropolysaccharides in vertebrate tissues that are also, in certain cases, employed as virulence factors by microbes. Hyaluronan [HA], heparin, and chondroitin sulfate [CS] are GAGs currently used in various medical applications and together are multi-billion dollar products thus targets for production by animal-free manufacture. By using bacteria as the source of GAGs, the pathogen's sword may be converted into a plowshare to help avoid potential liabilities springing from the use of animal-derived GAGs including adventitious agents (e.g., prions, pathogens), antigenicity, degradation of the environment, and depletion of endangered species. HA from microbes, which have a chemical structure identical to human HA, has already been commercialized and sold at the ton-scale. Substantial progress towards microbial heparin and CS has been made, but these vertebrate polymers are more complicated structurally than the unsulfated bacterial polysaccharide precursors thus require additional processing steps. This review provides an overview of GAG structure, medical applications, microbial biosynthesis, and the state of bacterial GAG production systems. Representatives of all glycosyltransferase enzymes that polymerize the sugar chains of the three main GAGs have been identified and serve as the core technology to harness, but the proteins involved in sugar precursor formation and chain export steps of biosynthesis are also essential to the GAG production process. In addition, this review discusses future directions and potential important issues. Overall, this area is poised to make great headway to produce safer (both increased purity and more secure supply chains) non-animal GAG-based therapeutics.
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Affiliation(s)
- Paul L DeAngelis
- Department of Biochemistry and Molecular Biology, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73126, USA.
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33
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Lanza AM, Alper HS. Using transcription machinery engineering to elicit complex cellular phenotypes. Methods Mol Biol 2012; 813:229-248. [PMID: 22083746 DOI: 10.1007/978-1-61779-412-4_14] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Cellular hosts are widely used for the production of chemical compounds, including pharmaceutics, fuels, and specialty chemicals. However, common metabolic engineering techniques are limited in their capacity to elicit multigenic, complex phenotypes. These phenotypes can include non-pathway-based traits, such as tolerance and productivity. Global transcription machinery engineering (gTME) is a generic methodology for eliciting these complex cellular phenotypes. In gTME, dominant mutant alleles of a transcription-related protein are screened for their ability to reprogram cellular metabolism and regulation, resulting in a unique and desired phenotype. gTME has been successfully applied to both prokaryotic and eukaryotic systems, resulting in improved environmental tolerances, metabolite production, and substrate utilization. The underlying principle involves creating mutant libraries of transcription factors, screening for a desired phenotype, and iterating the process in a directed evolution fashion. The successes of this approach and details for its implementation and application are described here.
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Affiliation(s)
- Amanda M Lanza
- Department of Chemical Engineering, The University of Texas at Austin, Austin, TX, USA
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Zhang H, Chong H, Ching CB, Jiang R. Random mutagenesis of global transcription factor cAMP receptor protein for improved osmotolerance. Biotechnol Bioeng 2011; 109:1165-72. [DOI: 10.1002/bit.24411] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2011] [Revised: 11/07/2011] [Accepted: 12/08/2011] [Indexed: 11/08/2022]
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Restriction enzyme-free construction of random gene mutagenesis libraries in Escherichia coli. Anal Biochem 2011; 421:640-8. [PMID: 22155067 DOI: 10.1016/j.ab.2011.11.009] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2011] [Revised: 11/07/2011] [Accepted: 11/10/2011] [Indexed: 11/22/2022]
Abstract
Directed evolution relies on both random and site-directed mutagenesis of individual genes and regulatory elements to create variants with altered activity profiles for engineering applications. Central to these experiments is the construction of large libraries of related variants. However, a number of technical hurdles continue to limit routine construction of random mutagenesis libraries in Escherichia coli, in particular, inefficiencies during digestion and ligation steps. Here, we report a restriction enzyme-free approach to library generation using megaprimers termed MegAnneal. Target DNA is first exponentially amplified using error-prone polymerase chain reaction (PCR) and then linearly amplified with a single 3' primer to generate long, randomly mutated, single-stranded megaprimers. These are annealed to single-stranded dUTP-containing template plasmid and extended with T7 polymerase to create a complementary strand, and the resulting termini are ligated with T4 DNA ligase. Using this approach, we are able to reliably generate libraries of approximately 10⁷ colony-forming units (cfu)/μg DNA/transformation in a single day. We have created MegAnneal libraries based on three different single-chain antibodies and identified variants with enhanced expression and ligand-binding affinity. The key advantages of this approach include facile amplification, restriction enzyme-free library generation, and a significantly reduced risk of mutations outside the targeted region and wild-type contamination as compared with current methods.
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Makino T, Skretas G, Georgiou G. Strain engineering for improved expression of recombinant proteins in bacteria. Microb Cell Fact 2011; 10:32. [PMID: 21569582 PMCID: PMC3120638 DOI: 10.1186/1475-2859-10-32] [Citation(s) in RCA: 139] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2011] [Accepted: 05/14/2011] [Indexed: 01/17/2023] Open
Abstract
Protein expression in Escherichia coli represents the most facile approach for the preparation of non-glycosylated proteins for analytical and preparative purposes. So far, the optimization of recombinant expression has largely remained a matter of trial and error and has relied upon varying parameters, such as expression vector, media composition, growth temperature and chaperone co-expression. Recently several new approaches for the genome-scale engineering of E. coli to enhance recombinant protein expression have been developed. These methodologies now enable the generation of optimized E. coli expression strains in a manner analogous to metabolic engineering for the synthesis of low-molecular-weight compounds. In this review, we provide an overview of strain engineering approaches useful for enhancing the expression of hard-to-produce proteins, including heterologous membrane proteins.
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Affiliation(s)
- Tomohiro Makino
- Department of Chemical Engineering, The University of Texas at Austin, 78712, USA
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Krivoruchko A, Siewers V, Nielsen J. Opportunities for yeast metabolic engineering: Lessons from synthetic biology. Biotechnol J 2011; 6:262-76. [DOI: 10.1002/biot.201000308] [Citation(s) in RCA: 94] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2010] [Revised: 01/06/2011] [Accepted: 01/13/2011] [Indexed: 11/08/2022]
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Abstract
Cellular hosts are widely used for the production of chemical compounds including pharmaceutics, fuels, and specialty chemicals. Strain engineering focuses on manipulating and improving these hosts for new and enhanced functionalities including increased titers and better bioreactor performance. These tasks have traditionally been accomplished using a combination of random mutation, screening and selection, and metabolic engineering. However, common metabolic engineering techniques are limited in their capacity to elicit multigenic, complex phenotypes. These phenotypes can also include nonpathway-based traits such as tolerance and productivity. Global transcription machinery engineering (gTME) is a generic methodology for engineering strains with these complex cellular phenotypes. In gTME, dominant mutant alleles of a transcription-related protein are screened for their ability to reprogram cellular metabolism and regulation, resulting in a unique and desired phenotype. gTME has been successfully applied to both prokaryotic and eukaryotic systems, resulting in improved environmental tolerances, metabolite production, and substrate utilization. The underlying principle involves creating mutant libraries of transcription factors, screening for a desired phenotype, and iterating the process in a directed evolution fashion. The successes of this approach and details for its implementation and application are described here.
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Affiliation(s)
- Amanda M Lanza
- Department of Chemical Engineering, The University of Texas at Austin, Austin, TX, USA
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Young E, Lee SM, Alper H. Optimizing pentose utilization in yeast: the need for novel tools and approaches. BIOTECHNOLOGY FOR BIOFUELS 2010; 3:24. [PMID: 21080929 PMCID: PMC2993683 DOI: 10.1186/1754-6834-3-24] [Citation(s) in RCA: 105] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/06/2010] [Accepted: 11/16/2010] [Indexed: 05/04/2023]
Abstract
Hexose and pentose cofermentation is regarded as one of the chief obstacles impeding economical conversion of lignocellulosic biomass to biofuels. Over time, successful application of traditional metabolic engineering strategy has produced yeast strains capable of utilizing the pentose sugars (especially xylose and arabinose) as sole carbon sources, yet major difficulties still remain for engineering simultaneous, exogenous sugar metabolism. Beyond catabolic pathways, the focus must shift towards non-traditional aspects of cellular engineering such as host molecular transport capability, catabolite sensing and stress response mechanisms. This review highlights the need for an approach termed 'panmetabolic engineering', a new paradigm for integrating new carbon sources into host metabolic pathways. This approach will concurrently optimize the interdependent processes of transport and metabolism using novel combinatorial techniques and global cellular engineering. As a result, panmetabolic engineering is a whole pathway approach emphasizing better pathways, reduced glucose-induced repression and increased product tolerance. In this paper, recent publications are reviewed in light of this approach and their potential to expand metabolic engineering tools. Collectively, traditional approaches and panmetabolic engineering enable the reprogramming of extant biological complexity and incorporation of exogenous carbon catabolism.
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Affiliation(s)
- Eric Young
- Department of Chemical Engineering, The University of Texas at Austin, 1 University Station, C0400, Austin, Texas 78712, USA
| | - Sun-Mi Lee
- Department of Chemical Engineering, The University of Texas at Austin, 1 University Station, C0400, Austin, Texas 78712, USA
- Water Environment Center, Korea Institute of Science and Technology, 39-1 Hawolgok-dong, Seongbuk-gu, Seoul 136-791, Korea
| | - Hal Alper
- Department of Chemical Engineering, The University of Texas at Austin, 1 University Station, C0400, Austin, Texas 78712, USA
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Dietrich JA, McKee AE, Keasling JD. High-throughput metabolic engineering: advances in small-molecule screening and selection. Annu Rev Biochem 2010; 79:563-90. [PMID: 20367033 DOI: 10.1146/annurev-biochem-062608-095938] [Citation(s) in RCA: 245] [Impact Index Per Article: 17.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Metabolic engineering for the overproduction of high-value small molecules is dependent upon techniques in directed evolution to improve production titers. The majority of small molecules targeted for overproduction are inconspicuous and cannot be readily obtained by screening. We provide a review on the development of high-throughput colorimetric, fluorescent, and growth-coupled screening techniques, enabling inconspicuous small-molecule detection. We first outline constraints on throughput imposed during the standard directed evolution workflow (library construction, transformation, and screening) and establish a screening and selection ladder on the basis of small-molecule assay throughput and sensitivity. An in-depth analysis of demonstrated screening and selection approaches for small-molecule detection is provided. Particular focus is placed on in vivo biosensor-based detection methods that reduce or eliminate in vitro assay manipulations and increase throughput. We conclude by providing our prospectus for the future, focusing on transcription factor-based detection systems as a natural microbial mode of small-molecule detection.
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Affiliation(s)
- Jeffrey A Dietrich
- UCSF-UCB Joint Graduate Group in Bioengineering, Berkeley, California 94720, USA.
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41
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Senger RS. Biofuel production improvement with genome-scale models: The role of cell composition. Biotechnol J 2010; 5:671-85. [DOI: 10.1002/biot.201000007] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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42
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Reverse biological engineering of hrdB to enhance the production of avermectins in an industrial strain of Streptomyces avermitilis. Proc Natl Acad Sci U S A 2010; 107:11250-4. [PMID: 20534557 DOI: 10.1073/pnas.1006085107] [Citation(s) in RCA: 74] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Avermectin and its analogues are produced by the actinomycete Streptomyces avermitilis and are widely used in the field of animal health, agriculture, and human health. Here we have adopted a practical approach to successfully improve avermectin production in an industrial overproducer. Transcriptional levels of the wild-type strain and industrial overproducer in production cultures were monitored using microarray analysis. The avermectin biosynthetic genes, especially the pathway-specific regulatory gene, aveR, were up-regulated in the high-producing strain. The upstream promoter region of aveR was predicted and proved to be directly recognized by sigma(hrdB) in vitro. A mutant library of hrdB gene was constructed by error-prone PCR and selected by high-throughput screening. As a result of evolved hrdB expressed in the modified avermectin high-producing strain, 6.38 g/L of avermectin B1a was produced with over 50% yield improvement, in which the transcription level of aveR was significantly increased. The relevant residues were identified to center in the conserved regions. Engineering of the hrdB gene can not only elicit the overexpression of aveR but also allows for simultaneous transcription of many other genes. The results indicate that manipulating the key genes revealed by reverse engineering can effectively improve the yield of the target metabolites, providing a route to optimize production in these complex regulatory systems.
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Enhancing stress resistance and production phenotypes through transcriptome engineering. Methods Enzymol 2010; 470:509-32. [PMID: 20946823 DOI: 10.1016/s0076-6879(10)70020-3] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/23/2023]
Abstract
As Saccharomyces cerevisiae is engineered further as a microbial factory for industrially relevant but potentially cytotoxic molecules such as ethanol, issues of cell viability arise that threaten to place a biological limit on output capacity and/or the use of less refined production conditions. Evidence suggests that one naturally evolved mode of survival in deleterious environments involves the complex, multigenic interplay between disparate stress response and homeostasis mechanisms. Rational engineering of such resistance would require a systems-level understanding of cellular behavior that is, in general, not yet available. To circumvent this limitation, we have developed a phenotype discovery approach termed global transcription machinery engineering (gTME) that allows for the generation and selection of nonphysiological traits. We alter gene expression on a genome-wide scale by selecting for dominant mutations in a randomly mutagenized general transcription factor. The gene encoding the mutated transcription factor resides on a plasmid in a strain carrying the unaltered chromosomal allele. Thus, although the dominant mutations may destroy the essential function of the plasmid-borne variant, alteration of the transcriptome with minimal perturbation to normal cellular processes is possible via the presence of the native genomic allele. Achieving a phenotype of interest involves the construction and diversity evaluation of yeast libraries harboring random sequence variants of a chosen transcription factor and the subsequent selection and validation of mutant strains. We describe the rationale and procedures associated with each step in the context of generating strains possessing enhanced ethanol tolerance.
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Application of Recombinant Fusion Proteins for Tissue Engineering. Ann Biomed Eng 2010; 38:683-93. [DOI: 10.1007/s10439-010-9935-3] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2009] [Accepted: 01/17/2010] [Indexed: 10/19/2022]
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Young E, Alper H. Synthetic biology: tools to design, build, and optimize cellular processes. J Biomed Biotechnol 2010; 2010:130781. [PMID: 20150964 PMCID: PMC2817555 DOI: 10.1155/2010/130781] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2009] [Accepted: 10/28/2009] [Indexed: 11/17/2022] Open
Abstract
The general central dogma frames the emergent properties of life, which make biology both necessary and difficult to engineer. In a process engineering paradigm, each biological process stream and process unit is heavily influenced by regulatory interactions and interactions with the surrounding environment. Synthetic biology is developing the tools and methods that will increase control over these interactions, eventually resulting in an integrative synthetic biology that will allow ground-up cellular optimization. In this review, we attempt to contextualize the areas of synthetic biology into three tiers: (1) the process units and associated streams of the central dogma, (2) the intrinsic regulatory mechanisms, and (3) the extrinsic physical and chemical environment. Efforts at each of these three tiers attempt to control cellular systems and take advantage of emerging tools and approaches. Ultimately, it will be possible to integrate these approaches and realize the vision of integrative synthetic biology when cells are completely rewired for biotechnological goals. This review will highlight progress towards this goal as well as areas requiring further research.
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Affiliation(s)
- Eric Young
- Department of Chemical Engineering, The University of Texas at Austin, 1 University Station, C0400, Austin, TX 78712, USA
| | - Hal Alper
- Department of Chemical Engineering, The University of Texas at Austin, 1 University Station, C0400, Austin, TX 78712, USA
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Identification of avermectin-high-producing strains by high-throughput screening methods. Appl Microbiol Biotechnol 2009; 85:1219-25. [PMID: 19957083 DOI: 10.1007/s00253-009-2345-5] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2009] [Revised: 11/05/2009] [Accepted: 11/07/2009] [Indexed: 10/20/2022]
Abstract
Avermectins produced by Streptomyces avermitilis are potent against a broad spectrum of nematode and arthropod parasites with low-level side effects on the host organisms. This study was designed to investigate a high-throughput screening strategy for the efficient identification of avermectin high-yield strains. The production protocol was miniaturized in 96 deep-well microplates. UV absorbance at 245 nm was used to monitor avermectin production. A good correlation between fermentation results in both 96 deep-well microplates and conventional Erlenmeyer flasks was observed. With this protocol, the production of avermectins was determined in less than 10 min for a full plate without compromising accuracy. The high-yield strain selected through this protocol was also tested in 360 m(3) batch fermentation with 1.6-fold improved outcome. Thus, the development of this protocol is expected to accelerate the selection of superior avermectin-producing strains.
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47
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Mutagenesis of the bacterial RNA polymerase alpha subunit for improvement of complex phenotypes. Appl Environ Microbiol 2009; 75:2705-11. [PMID: 19251886 DOI: 10.1128/aem.01888-08] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Combinatorial or random methods for strain engineering have been extensively used for the improvement of multigenic phenotypes and other traits for which the underlying mechanism is not fully understood. Although the preferred method has traditionally been mutagenesis and selection, our laboratory has successfully used mutant transcription factors, which direct the RNA polymerase (RNAP) during transcription, to engineer complex phenotypes in microbial cells. Here, we show that it is also possible to impart new phenotypes by altering the RNAP core enzyme itself, in particular through mutagenesis of the alpha subunit of the bacterial polymerase. We present the use of this tool for improving tolerance of Escherichia coli to butanol and other solvents and for increasing the titers of two commercially relevant products, L-tyrosine and hyaluronic acid. In addition, we explore the underlying physiological changes that give rise to the solvent-tolerant mutant.
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