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Li B, Huang LG, Yang YF, Chen YY, Zhou XJ, Liu ZQ, Zheng YG. Metabolic engineering and pathway construction for O-acetyl-L-homoserine production in Escherichia coli. 3 Biotech 2023; 13:173. [PMID: 37188286 PMCID: PMC10170018 DOI: 10.1007/s13205-023-03564-5] [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: 10/31/2022] [Accepted: 04/15/2023] [Indexed: 05/17/2023] Open
Abstract
O-Acetyl-L-homoserine (OAH) is a potentially important platform metabolic intermediate for the production of homoserine lactone, methionine, 1,4-butanediol and 1,3-propanediol which have giant market value. Currently, multiple strategies have been adopted to explore sustainable production of OAH. However, the production of OAH by consuming cheap bio-based feedstocks with Escherichia coli as the chassis is still in its infancy. Construction of high yield OAH-producing strains is of great significance in industry. In this study, we introduced an exogenous metA from Bacillus cereus (metXbc) and engineered an OAH-producing strain by combinatorial metabolic engineering. Initially, exogenous metXs/metA were screened and used to reconstruct an initial biosynthesis pathway of OAH in E. coli. Subsequently, the disruption of degradation and competitive pathways combined with optimal expression of metXbc were carried out, accumulating 5.47 g/L OAH. Meanwhile, the homoserine pool was enriched by overexpressing metL with producing 7.42 g/L OAH. Lastly, the carbon flux of central carbon metabolism was redistributed to balance the metabolic flux of homoserine and acetyl coenzyme A (acetyl-CoA) in OAH biosynthesis with accumulating 8.29 g/L OAH. The engineered strain produced 24.33 g/L OAH with a yield of 0.23 g/g glucose in fed-batch fermentation. By these strategies, the key nodes for OAH synthesis were clarified and corresponding strategies were proposed. This study would lay a foundation for OAH bioproduction. Supplementary Information The online version contains supplementary material available at 10.1007/s13205-023-03564-5.
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Affiliation(s)
- Bo Li
- Key Laboratory of Bioorganic Synthesis of Zhejiang Province, College of Biotechnology and Bioengineering, Zhejiang University of Technology, 18 Chaowang Road, Hangzhou, 310014 People’s Republic of China
- The National and Local Joint Engineering Research Center for Biomanufacturing of Chiral Chemicals, Zhejiang University of Technology, 18 Chaowang Road, Hangzhou, 310014 People’s Republic of China
| | - Liang-Gang Huang
- Key Laboratory of Bioorganic Synthesis of Zhejiang Province, College of Biotechnology and Bioengineering, Zhejiang University of Technology, 18 Chaowang Road, Hangzhou, 310014 People’s Republic of China
- The National and Local Joint Engineering Research Center for Biomanufacturing of Chiral Chemicals, Zhejiang University of Technology, 18 Chaowang Road, Hangzhou, 310014 People’s Republic of China
| | - Yu-Feng Yang
- Key Laboratory of Bioorganic Synthesis of Zhejiang Province, College of Biotechnology and Bioengineering, Zhejiang University of Technology, 18 Chaowang Road, Hangzhou, 310014 People’s Republic of China
- The National and Local Joint Engineering Research Center for Biomanufacturing of Chiral Chemicals, Zhejiang University of Technology, 18 Chaowang Road, Hangzhou, 310014 People’s Republic of China
| | - Yuan-Yuan Chen
- Key Laboratory of Bioorganic Synthesis of Zhejiang Province, College of Biotechnology and Bioengineering, Zhejiang University of Technology, 18 Chaowang Road, Hangzhou, 310014 People’s Republic of China
- The National and Local Joint Engineering Research Center for Biomanufacturing of Chiral Chemicals, Zhejiang University of Technology, 18 Chaowang Road, Hangzhou, 310014 People’s Republic of China
| | - Xiao-Jie Zhou
- Key Laboratory of Bioorganic Synthesis of Zhejiang Province, College of Biotechnology and Bioengineering, Zhejiang University of Technology, 18 Chaowang Road, Hangzhou, 310014 People’s Republic of China
- The National and Local Joint Engineering Research Center for Biomanufacturing of Chiral Chemicals, Zhejiang University of Technology, 18 Chaowang Road, Hangzhou, 310014 People’s Republic of China
| | - Zhi-Qiang Liu
- Key Laboratory of Bioorganic Synthesis of Zhejiang Province, College of Biotechnology and Bioengineering, Zhejiang University of Technology, 18 Chaowang Road, Hangzhou, 310014 People’s Republic of China
- The National and Local Joint Engineering Research Center for Biomanufacturing of Chiral Chemicals, Zhejiang University of Technology, 18 Chaowang Road, Hangzhou, 310014 People’s Republic of China
| | - Yu-Guo Zheng
- Key Laboratory of Bioorganic Synthesis of Zhejiang Province, College of Biotechnology and Bioengineering, Zhejiang University of Technology, 18 Chaowang Road, Hangzhou, 310014 People’s Republic of China
- The National and Local Joint Engineering Research Center for Biomanufacturing of Chiral Chemicals, Zhejiang University of Technology, 18 Chaowang Road, Hangzhou, 310014 People’s Republic of China
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2
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Xiong Z, Zhang X, White JC, Liu L, Sun W, Zhang S, Zeng J, Deng S, Liu D, Zhao X, Wu F, Zhao Q, Xing B. Transcriptome Analysis Reveals the Growth Promotion Mechanism of Enteropathogenic Escherichia coli Induced by Black Phosphorus Nanosheets. ACS NANO 2023; 17:3574-3586. [PMID: 36602915 DOI: 10.1021/acsnano.2c09964] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
With the extensive production and application of black phosphorus (BP) nanosheets, release to the environment is inevitable, which raises concerns about the fate and effects of this two-dimensional (2D) material on sensitive receptors such as environmental microbes. Although the bacterial toxicity of BP nanosheets has been demonstrated, whether the biological response differs in pathogenic and nonpathogenic strains of a microorganism is unknown. Here, enteropathogenic Escherichia coli (EPEC) and nonpathogenic Escherichia coli DH5α (E. coli DH5α), Escherichia coli k12 (E. coli k12), and Bacillus tropicus (B. tropicus) are used to comparatively study the microbial toxicity of BP nanosheets. Upon exposure to BP nanosheets across a range of doses from 10 to 100 μg mL-1 for 12 h, EPEC experienced enhanced growth and E. coli DH5α and E. coli k12 were not affected, whereas B. tropicus exhibited clear toxicity. By combining transcriptome sequencing, proteome analysis, and other sensitive biological techniques, the mechanism of BP-induced growth promotion for EPEC was uncovered. Briefly, BP nanosheets activate the antioxidation system to resist oxidative stress, promote protein synthesis and secretion to attenuate membrane damage, enhance the energy supply, and activate growth-related pathways. None of these impacts were evident with nonpathogenic strains. By describing the mechanism of strain-dependent microbial effects, this study not only highlights the potential risks of BP nanosheets to the environment and to human health but also calls attention to the importance of model strain selection when evaluating the hazard and toxicity of emerging nanomaterials.
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Affiliation(s)
- Zhiqiang Xiong
- National-Regional Joint Engineering Research Center for Soil Pollution Control and Remediation in South China, Guangdong Key Laboratory of Integrated Agro-environmental Pollution Control and Management, Institute of Eco-environmental and Soil Sciences, Guangdong Academy of Sciences, Guangzhou 510650, China
- Key Laboratory of Pollution Ecology and Environmental Engineering, Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang 110016, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Xuejiao Zhang
- National-Regional Joint Engineering Research Center for Soil Pollution Control and Remediation in South China, Guangdong Key Laboratory of Integrated Agro-environmental Pollution Control and Management, Institute of Eco-environmental and Soil Sciences, Guangdong Academy of Sciences, Guangzhou 510650, China
- Key Laboratory of Pollution Ecology and Environmental Engineering, Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang 110016, China
| | - Jason C White
- Department of Analytical Chemistry, The Connecticut Agricultural Experiment Station, New Haven, Connecticut 06504, United States
| | - Liwei Liu
- Li Dak Sum Marine Biopharmaceutical Research Center, Department of Marine Pharmacy, College of Food and Pharmaceutical Sciences, Ningbo University, Ningbo, Zhejiang 315832, China
| | - Weimin Sun
- National-Regional Joint Engineering Research Center for Soil Pollution Control and Remediation in South China, Guangdong Key Laboratory of Integrated Agro-environmental Pollution Control and Management, Institute of Eco-environmental and Soil Sciences, Guangdong Academy of Sciences, Guangzhou 510650, China
| | - Siyu Zhang
- Key Laboratory of Pollution Ecology and Environmental Engineering, Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang 110016, China
| | - Jin Zeng
- Key Laboratory of Pollution Ecology and Environmental Engineering, Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang 110016, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Shuo Deng
- Key Laboratory of Pollution Ecology and Environmental Engineering, Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang 110016, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Daxu Liu
- Key Laboratory of Pollution Ecology and Environmental Engineering, Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang 110016, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Xiaoli Zhao
- State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012, China
| | - Fengchang Wu
- State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012, China
| | - Qing Zhao
- National-Regional Joint Engineering Research Center for Soil Pollution Control and Remediation in South China, Guangdong Key Laboratory of Integrated Agro-environmental Pollution Control and Management, Institute of Eco-environmental and Soil Sciences, Guangdong Academy of Sciences, Guangzhou 510650, China
- Key Laboratory of Pollution Ecology and Environmental Engineering, Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang 110016, China
| | - Baoshan Xing
- Stockbridge School of Agriculture, University of Massachusetts, Amherst, Massachusetts 01003, United States
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Key amino acid residues in homoserine-acetyltransferase from M. tuberculosis give insight into the evolution of MetX family of enzymes - HAT, SAT and HST. Biochimie 2021; 189:13-25. [PMID: 34090964 DOI: 10.1016/j.biochi.2021.05.016] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2021] [Revised: 05/23/2021] [Accepted: 05/30/2021] [Indexed: 11/22/2022]
Abstract
Multiple sequence alignment of homoserine-acetyltransferases, serine-acetyltransferases and homoserine-succinyltransferases show they all belong to MetX family, having evolved from a common ancestor by conserving the catalytic site and substrate binding residues. The discrimination in the substrate selection arises due to the presence of substrate-specific residues lining the substrate-binding pocket. Mutation of Ala59 and Gly62 to Gly and Pro respectively in homoserine-acetyltransferase from M. tuberculosis resulted in a serine-acetyltransferase like enzyme as it acetylated both l-homoserine and l-serine. Homoserine-acetyltransferase from M. tuberculosis when mutated at positon 322 where Leu was converted to Arg, resulted in succinylation over acetylation of l-homoserine. Our studies establish the importance of the substrate binding residues in determining the type of activity possessed by MetX family, despite all of them having the same catalytic triad Ser-Asp-His. Hence key residues at the substrate binding pocket dictate whether the given enzyme shows predominant transferase or hydrolase activity.
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Matos D, Sá C, Cardoso P, Pires A, Figueira E. Rhizobium sensing of airborne saturated aldehydes of different sizes modulates the response to Cd exposure. JOURNAL OF HAZARDOUS MATERIALS 2020; 395:122629. [PMID: 32311516 DOI: 10.1016/j.jhazmat.2020.122629] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/07/2020] [Revised: 03/30/2020] [Accepted: 03/31/2020] [Indexed: 06/11/2023]
Abstract
α,β-unsaturated aldehydes are generally reported as being toxic, however for saturated aldehydes information is scarce. Here we report the effects on growth and biochemical endpoints related to oxidative stress of Rhizobium colonies under airborne exposure to C6 to C13 saturated aliphatic aldehydes and exposed or not to Cd. Smaller aldehydes (C6 to C10) and larger aldehydes (C11 to C13) had distinct effects on cell biochemistry. Smaller aldehydes reduced and larger ones increased lipid peroxidation. The activity of superoxide dismutase was also decreased by smaller aldehydes and increased by the larger ones. Thus, even an exposure at a distance to saturated aldehydes is able to influence the biochemical status of bacterial cells, and the effects appear to be dependent on the size and thus on distinct properties (e.g. volatility and liposolubility). Moreover, some aldehydes (the smaller saturated ones) may even have a beneficial effect, that switches when cells are in oxidative stress (exposed to Cd). This influence can be used in different contexts, by increasing the resilience of bacterial communities to environmental contaminants with oxidizing effect or by sensitizing bacteria to antimicrobial agents.
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Affiliation(s)
- Diana Matos
- Department of Biology, University of Aveiro, Aveiro, Portugal
| | - Carina Sá
- Department of Biology, University of Aveiro, Aveiro, Portugal
| | - Paulo Cardoso
- Department of Biology & CESAM, University of Aveiro, Aveiro, Portugal
| | - Adília Pires
- Department of Biology & CESAM, University of Aveiro, Aveiro, Portugal
| | - Etelvina Figueira
- Department of Biology & CESAM, University of Aveiro, Aveiro, Portugal.
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5
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Jiang X, Dulubova I, Reisman SA, Hotema M, Lee CYI, Liu L, McCauley L, Trevino I, Ferguson DA, Eken Y, Wilson AK, Wigley WC, Visnick M. A novel series of cysteine-dependent, allosteric inverse agonists of the nuclear receptor RORγt. Bioorg Med Chem Lett 2020; 30:126967. [PMID: 32005415 DOI: 10.1016/j.bmcl.2020.126967] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2019] [Revised: 01/10/2020] [Accepted: 01/11/2020] [Indexed: 12/22/2022]
Abstract
Inhibition of the nuclear receptor Retinoic Acid Receptor-Related Orphan Receptor γt (RORγt) is a promising strategy for the treatment of autoimmune diseases. In this paper, we describe a series of allosteric, cysteine-dependent, inverse agonists of RORγt. Site-directed mutagenesis and molecular dynamics simulations are supportive of a mechanism of action through specific binding to Cys476 on alpha helix 11 of the ligand binding domain (LBD). Representative compounds in the series selectively inhibit RORγt, potently suppress interleukin-17A (IL-17A) production by human CD4+ T cells, and inhibit T helper 17 (Th17) differentiation from human naïve CD4+ T cells. The advanced compound 13 is orally bioavailable and active at a dose of 3 mg/kg in a murine collagen-induced model of rheumatoid arthritis. Collectively, these data are supportive of the development of compound 13 in autoimmune diseases.
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Affiliation(s)
- Xin Jiang
- Reata Pharmaceuticals, Inc., 2801 Gateway Drive, Suite 150, Irving, TX 75063, USA
| | - Irina Dulubova
- Reata Pharmaceuticals, Inc., 2801 Gateway Drive, Suite 150, Irving, TX 75063, USA
| | - Scott A Reisman
- Reata Pharmaceuticals, Inc., 2801 Gateway Drive, Suite 150, Irving, TX 75063, USA
| | - Martha Hotema
- Reata Pharmaceuticals, Inc., 2801 Gateway Drive, Suite 150, Irving, TX 75063, USA
| | - Chun-Yue I Lee
- Reata Pharmaceuticals, Inc., 2801 Gateway Drive, Suite 150, Irving, TX 75063, USA
| | - Liping Liu
- Reata Pharmaceuticals, Inc., 2801 Gateway Drive, Suite 150, Irving, TX 75063, USA
| | - Lyndsey McCauley
- Reata Pharmaceuticals, Inc., 2801 Gateway Drive, Suite 150, Irving, TX 75063, USA
| | - Isaac Trevino
- Reata Pharmaceuticals, Inc., 2801 Gateway Drive, Suite 150, Irving, TX 75063, USA
| | - Deborah A Ferguson
- Reata Pharmaceuticals, Inc., 2801 Gateway Drive, Suite 150, Irving, TX 75063, USA
| | - Yigitcan Eken
- Department of Chemistry, Michigan State University, 578 South Shaw Lane, East Lansing, MI 48824, USA
| | - Angela K Wilson
- Department of Chemistry, Michigan State University, 578 South Shaw Lane, East Lansing, MI 48824, USA
| | - W Christian Wigley
- Reata Pharmaceuticals, Inc., 2801 Gateway Drive, Suite 150, Irving, TX 75063, USA
| | - Melean Visnick
- Reata Pharmaceuticals, Inc., 2801 Gateway Drive, Suite 150, Irving, TX 75063, USA.
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6
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Matos D, Sá C, Cardoso P, Pires A, Rocha SM, Figueira E. The role of volatiles in Rhizobium tolerance to cadmium: Effects of aldehydes and alcohols on growth and biochemical endpoints. ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2019; 186:109759. [PMID: 31606646 DOI: 10.1016/j.ecoenv.2019.109759] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/21/2019] [Revised: 09/30/2019] [Accepted: 10/02/2019] [Indexed: 06/10/2023]
Abstract
Rhizobia have a significant agronomic and environmental role and are eminent contributors to soil fertility. However, this group of microorganisms are affected by various environmental stresses, such as Cd contamination. High Cd concentrations change bacterial metabolism. During this metabolic shift, bacteria alter their volatilome (the set of volatile metabolites synthesized by an organism). In the presence of Cd, peak areas of saturated aldehydes and alcohols were previously reported to increase, and the consequences of this increase to cells are poorly known. In this study, Rhizobium sp. strain E20-8 cells were exposed to Cd and aldehydes or their conjugated alcohols. Exposure to Cd (100 μM) inhibited cell growth and induced several biomarkers of oxidative stress. The present study also evidenced the higher toxicity of most aldehydes relatively to the corresponding alcohol in the presence of Cd, suggesting that reduction of aldehydes into alcohols may be an effective mechanism to restrain aldehydes toxicity in Rhizobium cells under Cd toxicity. Nonetheless, the protective effect was dependent on the pair aldehyde-respective alcohol considered and it differed between Cd stressed and non-stressed cells. Differences in the ability to convert aldehydes to alcohols may emerge as a new feature helping explain the oxidative tolerance variability among bacteria.
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Affiliation(s)
- Diana Matos
- Department of Biology, University of Aveiro, Aveiro, Portugal
| | - Carina Sá
- Department of Biology, University of Aveiro, Aveiro, Portugal
| | - Paulo Cardoso
- Department of Biology & CESAM, University of Aveiro, Aveiro, Portugal
| | - Adília Pires
- Department of Biology & CESAM, University of Aveiro, Aveiro, Portugal
| | - Sílvia M Rocha
- Department of Chemistry & QOPNA/LAQV-REQUIMTE, University of Aveiro, Aveiro, Portugal
| | - Etelvina Figueira
- Department of Biology & CESAM, University of Aveiro, Aveiro, Portugal.
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Zou R, Shi W, Tao J, Li H, Lin X, Yang S, Hua P. SIRT5 and post-translational protein modifications: A potential therapeutic target for myocardial ischemia-reperfusion injury with regard to mitochondrial dynamics and oxidative metabolism. Eur J Pharmacol 2018; 818:410-418. [DOI: 10.1016/j.ejphar.2017.11.005] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2017] [Revised: 10/23/2017] [Accepted: 11/01/2017] [Indexed: 11/27/2022]
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8
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Shim J, Shin Y, Lee I, Kim SY. l-Methionine Production. ADVANCES IN BIOCHEMICAL ENGINEERING/BIOTECHNOLOGY 2016; 159:153-177. [DOI: 10.1007/10_2016_30] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
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Wang H, Wang F, Wang W, Yao X, Wei D, Cheng H, Deng Z. Improving the expression of recombinant proteins in E. coli BL21 (DE3) under acetate stress: an alkaline pH shift approach. PLoS One 2014; 9:e112777. [PMID: 25402470 PMCID: PMC4234529 DOI: 10.1371/journal.pone.0112777] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2014] [Accepted: 10/20/2014] [Indexed: 11/23/2022] Open
Abstract
Excess acetate has long been an issue for the production of recombinant proteins in E. coli cells. Recently, improvements in acetate tolerance have been achieved through the use of genetic strategies and medium supplementation with certain amino acids and pyrimidines. The aim of our study was to evaluate an alternative to improve the acetate tolerance of E. coli BL21 (DE3), a popular strain used to express recombinant proteins. In this work we reported the cultivation of BL21 (DE3) in complex media containing acetate at high concentrations. In the presence of 300 mM acetate, compared with pH 6.5, pH 7.5 improved cell growth by approximately 71%, reduced intracellular acetate by approximately 50%, and restored the expression of glutathione S-transferase (GST), green fluorescent protein (GFP) and cytochrome P450 monooxygenase (CYP). Further experiments showed that alkaline pHs up to 8.5 had little inhibition in the expression of GST, GFP and CYP. In addition, the detrimental effect of acetate on the reduction of 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) by the cell membrane, an index of cellular metabolic capacity, was substantially alleviated by a shift to alkaline pH values of 7.5–8.0. Thus, we suggest an approach of cultivating E. coli BL21 (DE3) at pH 8.0±0.5 to minimize the effects caused by acetate stress. The proposed strategy of an alkaline pH shift is a simple approach to solving similar bioprocessing problems in the production of biofuels and biochemicals from sugars.
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Affiliation(s)
- Hengwei Wang
- Innovation & Application Institute (IAI), Zhejiang Ocean University, Zhoushan, China
- State Key Laboratory of Microbial Metabolism, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, China
| | - Fengqing Wang
- New World Institute of Biotechnology, State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai, China
| | - Wei Wang
- New World Institute of Biotechnology, State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai, China
| | - Xueling Yao
- New World Institute of Biotechnology, State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai, China
| | - Dongzhi Wei
- New World Institute of Biotechnology, State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai, China
| | - Hairong Cheng
- State Key Laboratory of Microbial Metabolism, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, China
- * E-mail:
| | - Zixin Deng
- State Key Laboratory of Microbial Metabolism, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, China
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Improved thermostability and acetic acid tolerance of Escherichia coli via directed evolution of homoserine o-succinyltransferase. Appl Environ Microbiol 2008; 74:7660-8. [PMID: 18978085 DOI: 10.1128/aem.00654-08] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
In Escherichia coli, growth is limited at elevated temperatures mainly because of the instability of a single enzyme, homoserine o-succinyltransferase (MetA), the first enzyme in the methionine biosynthesis pathway. The metA gene from the thermophile Geobacillus kaustophilus cloned into the E. coli chromosome was found to enhance the growth of the host strain at elevated temperature (44 degrees C), thus confirming the limited growth of E. coli due to MetA instability. In order to improve E. coli growth at higher temperatures, we used random mutagenesis to obtain a thermostable MetA(E. coli) protein. Sequencing of the thermotolerant mutant showed five amino acid substitutions: S61T, E213V, I229T, N267D, and N271K. An E. coli strain with the mutated metA gene chromosomally inserted showed accelerated growth over a temperature range of 34 to 44 degrees C. We used the site-directed metA mutants to identify two amino acid residues responsible for the sensitivity of MetA(E. coli) to both heat and acids. Replacement of isoleucine 229 with threonine and asparagine 267 with aspartic acid stabilized the protein. The thermostable MetA(E. coli) enzymes showed less aggregation in vivo at higher temperature, as well as upon acetic acid treatment. The data presented here are the first to show improved E. coli growth at higher temperatures solely due to MetA stabilization and provide new knowledge for designing E. coli strains that grow at higher temperatures, thus reducing the cooling cost of bioprocesses.
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11
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Zubieta C, Arkus KAJ, Cahoon RE, Jez JM. A single amino acid change is responsible for evolution of acyltransferase specificity in bacterial methionine biosynthesis. J Biol Chem 2008; 283:7561-7. [PMID: 18216013 DOI: 10.1074/jbc.m709283200] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Bacteria and yeast rely on either homoserine transsuccinylase (HTS, metA) or homoserine transacetylase (HTA; met2) for the biosynthesis of methionine. Although HTS and HTA catalyze similar chemical reactions, these proteins are typically unrelated in both sequence and three-dimensional structure. Here we present the 2.0 A resolution x-ray crystal structure of the Bacillus cereus metA protein in complex with homoserine, which provides the first view of a ligand bound to either HTA or HTS. Surprisingly, functional analysis of the B. cereus metA protein shows that it does not use succinyl-CoA as a substrate. Instead, the protein catalyzes the transacetylation of homoserine using acetyl-CoA. Therefore, the B. cereus metA protein functions as an HTA despite greater than 50% sequence identity with bona fide HTS proteins. This result emphasizes the need for functional confirmation of annotations of enzyme function based on either sequence or structural comparisons. Kinetic analysis of site-directed mutants reveals that the B. cereus metA protein and the E. coli HTS share a common catalytic mechanism. Structural and functional examination of the B. cereus metA protein reveals that a single amino acid in the active site determines acetyl-CoA (Glu-111) versus succinyl-CoA (Gly-111) specificity in the metA-like of acyltransferases. Switching of this residue provides a mechanism for evolving substrate specificity in bacterial methionine biosynthesis. Within this enzyme family, HTS and HTA activity likely arises from divergent evolution in a common structural scaffold with conserved catalytic machinery and homoserine binding sites.
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Affiliation(s)
- Chloe Zubieta
- Donald Danforth Plant Science Center, St. Louis, Missouri 63132, USA
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12
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Ziegler K, Yusupov M, Bishop B, Born TL. Substrate analysis of homoserine acyltransferase from Bacillus cereus. Biochem Biophys Res Commun 2007; 361:510-5. [PMID: 17662245 PMCID: PMC2043379 DOI: 10.1016/j.bbrc.2007.07.044] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2007] [Accepted: 07/12/2007] [Indexed: 11/19/2022]
Abstract
Substrate specificity within the family of enzymes designated as homoserine transsuccinylases is variable, with some organisms utilizing succinyl-CoA and other organisms utilizing acetyl-CoA. In this study it is shown that the enzyme from Bacillus cereus uses acetyl-CoA as its acyl donor, but its catalytic rate is significantly lower than other HTS family members. BcHTS is inactivated by both iodoacetamide and diethyl pyrocarbonate and the enzyme can be partially protected from inactivation by the presence of succinyl-CoA. This leads to the conclusion that BcHTS can bind both acetyl-CoA and succinyl-CoA and suggests that it may represent an intermediate between the succinate-transferring HTS family members and the acetate-transferring HTS family members. The B. cereus enzyme was unable to rescue growth of an Escherichia coli strain lacking a functional transsuccinylase, however.
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Affiliation(s)
- Katharine Ziegler
- Department of Chemistry and Biochemistry, George Mason University, 10900 University Blvd, Manassas, VA 20110, USA
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