1
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Zhang W, Liu K, Kong F, Ye T, Wang T. Multiple Functions of Compatible Solute Ectoine and Strategies for Constructing Overproducers for Biobased Production. Mol Biotechnol 2024; 66:1772-1785. [PMID: 37488320 DOI: 10.1007/s12033-023-00827-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2023] [Accepted: 07/14/2023] [Indexed: 07/26/2023]
Abstract
Ectoine and its derivative 5-hydroxyectoine are compatible solutes initially found in the hyperhalophilic bacterium Ectothiorhodospira halochloris, which inhabits the desert in Egypt. The habitat of ectoine producers implies the primary function of ectoine as a cytoprotectant against harsh conditions such as high salinity, drought, and high radiation. More extensive and in-depth studies have revealed the multiple functions of ectoine in its native producer bacterial cells and other types of cells and its biomolecular components (such as proteins and DNA) as a general protective agent. Its chemical properties as a bio-based amino acid derivative make it attractive for basic scientific research and related industries, such as the food/agricultural industry, cosmetic manufacturing, biologics, and therapeutic agent preparation. This article first discusses the functions and applications of ectoine and 5-hydroxyectoine. Subsequently, more emphasis was placed on advances in bio-based ectoine and/or 5-hydroxyectoine production. Strategies for developing more robust cell factories for highly efficient ectoine and/or 5-hydroxyectoine production are further discussed. We hope this review will provide a valuable reference for studies on the bio-based production of ectoine and 5-hydroxyectoine.
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Affiliation(s)
- Wei Zhang
- College of Life Sciences, Xinyang Normal University, Xinyang, 464000, People's Republic of China
| | - Kun Liu
- College of Biology and Food Engineering, Anhui Polytechnic University, Wuhu, 241000, People's Republic of China
| | - Fang Kong
- College of Biology and Food Engineering, Anhui Polytechnic University, Wuhu, 241000, People's Republic of China
| | - Tao Ye
- College of Biology and Food Engineering, Anhui Polytechnic University, Wuhu, 241000, People's Republic of China
| | - Tianwen Wang
- College of Biology and Food Engineering, Anhui Polytechnic University, Wuhu, 241000, People's Republic of China.
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2
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Yang N, Liu M, Han J, Jiang M, Zeng Y, Liu Y, Xiang H, Zheng Y. Rational engineering of Halomonas salifodinae to enhance hydroxyectoine production under lower-salt conditions. Appl Microbiol Biotechnol 2024; 108:353. [PMID: 38819481 PMCID: PMC11142988 DOI: 10.1007/s00253-024-13197-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2023] [Revised: 05/01/2024] [Accepted: 05/21/2024] [Indexed: 06/01/2024]
Abstract
Hydroxyectoine is an important compatible solute that holds potential for development into a high-value chemical with broad applications. However, the traditional high-salt fermentation for hydroxyectoine production presents challenges in treating the high-salt wastewater. Here, we report the rational engineering of Halomonas salifodinae to improve the bioproduction of hydroxyectoine under lower-salt conditions. The comparative transcriptomic analysis suggested that the increased expression of ectD gene encoding ectoine hydroxylase (EctD) and the decreased expressions of genes responsible for tricarboxylic acid (TCA) cycle contributed to the increased hydroxyectoine production in H. salifodinae IM328 grown under high-salt conditions. By blocking the degradation pathway of ectoine and hydroxyectoine, enhancing the expression of ectD, and increasing the supply of 2-oxoglutarate, the engineered H. salifodinae strain HS328-YNP15 (ΔdoeA::PUP119-ectD p-gdh) produced 8.3-fold higher hydroxyectoine production than the wild-type strain and finally achieved a hydroxyectoine titer of 4.9 g/L in fed-batch fermentation without any detailed process optimization. This study shows the potential to integrate hydroxyectoine production into open unsterile fermentation process that operates under low-salinity and high-alkalinity conditions, paving the way for next-generation industrial biotechnology. KEY POINTS: • Hydroxyectoine production in H. salifodinae correlates with the salinity of medium • Transcriptomic analysis reveals the limiting factors for hydroxyectoine production • The engineered strain produced 8.3-fold more hydroxyectoine than the wild type.
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Affiliation(s)
- Niping Yang
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, No.1 Beichen West Road, Chaoyang District, Beijing, 100101, China
- School of Life Sciences, Hebei University, Baoding, 071002, China
| | - Mengshuang Liu
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, No.1 Beichen West Road, Chaoyang District, Beijing, 100101, China
- College of Life Science, University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Jing Han
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, No.1 Beichen West Road, Chaoyang District, Beijing, 100101, China
| | - Mingyue Jiang
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, No.1 Beichen West Road, Chaoyang District, Beijing, 100101, China
- College of Life Science, University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Yan Zeng
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, No.1 Beichen West Road, Chaoyang District, Beijing, 100101, China
| | - Ying Liu
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, No.1 Beichen West Road, Chaoyang District, Beijing, 100101, China
| | - Hua Xiang
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, No.1 Beichen West Road, Chaoyang District, Beijing, 100101, China
- College of Life Science, University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Yanning Zheng
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, No.1 Beichen West Road, Chaoyang District, Beijing, 100101, China.
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3
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Li L, Li N, Wang X, Gao S, Zhang J, Zhou J, Wu Z, Zeng W. Metabolic engineering combined with enzyme engineering for overproduction of ectoine in Escherichia coli. BIORESOURCE TECHNOLOGY 2023; 390:129862. [PMID: 37839643 DOI: 10.1016/j.biortech.2023.129862] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/26/2023] [Revised: 10/09/2023] [Accepted: 10/10/2023] [Indexed: 10/17/2023]
Abstract
Ectoine, a natural protective agent, is naturally synthesized at low titers by some extreme environment microorganisms that are usually difficult to culture. There is a need for an efficient and eco-friendly ectoine production process. In this study, Escherichia coli BL21(DE3) with the ectABC gene cluster from Halomonas venusta achieved 1.7 g/L ectoine. After optimizing the expression plasmid, 2.1 g/L ectoine was achieved. Besides, the aspartate kinase mutant LysCT311I from Corynebacterium glutamicum and aspartate semialdehyde dehydrogenase from Halomonas elongata were overexpressed to increase precursors supply. Furthermore, the rate-limiting enzyme EctB was semirationally engineered, and the E407D mutation enhanced ectoine production by 13.8 %. To improve acetyl-CoA supply, the non-oxidative glycolysis pathway was introduced. Overall, the optimized strain ECT9-5 produced 67.1 g/L ectoine by fed-batch fermentation with a 0.3 g/g of glucose and the kinetic model resulted in a good fit.
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Affiliation(s)
- Lihong Li
- Engineering Research Center of Ministry of Education on Food Synthetic Biotechnology, Jiangnan University, 1800 Lihu Road, Wuxi, Jiangsu 214122, China; Science Center for Future Foods, Jiangnan University, 1800 Lihu Road, Wuxi, Jiangsu 214122, China
| | - Ning Li
- Engineering Research Center of Ministry of Education on Food Synthetic Biotechnology, Jiangnan University, 1800 Lihu Road, Wuxi, Jiangsu 214122, China; Science Center for Future Foods, Jiangnan University, 1800 Lihu Road, Wuxi, Jiangsu 214122, China; Key Laboratory of Industrial Biotechnology, Ministry of Education and School of Biotechnology, Jiangnan University, 1800 Lihu Road, Wuxi, Jiangsu 214122, China
| | - Xinglong Wang
- Engineering Research Center of Ministry of Education on Food Synthetic Biotechnology, Jiangnan University, 1800 Lihu Road, Wuxi, Jiangsu 214122, China; Science Center for Future Foods, Jiangnan University, 1800 Lihu Road, Wuxi, Jiangsu 214122, China
| | - Song Gao
- Engineering Research Center of Ministry of Education on Food Synthetic Biotechnology, Jiangnan University, 1800 Lihu Road, Wuxi, Jiangsu 214122, China; Science Center for Future Foods, Jiangnan University, 1800 Lihu Road, Wuxi, Jiangsu 214122, China
| | - Juan Zhang
- Engineering Research Center of Ministry of Education on Food Synthetic Biotechnology, Jiangnan University, 1800 Lihu Road, Wuxi, Jiangsu 214122, China; Science Center for Future Foods, Jiangnan University, 1800 Lihu Road, Wuxi, Jiangsu 214122, China
| | - Jingwen Zhou
- Engineering Research Center of Ministry of Education on Food Synthetic Biotechnology, Jiangnan University, 1800 Lihu Road, Wuxi, Jiangsu 214122, China; Science Center for Future Foods, Jiangnan University, 1800 Lihu Road, Wuxi, Jiangsu 214122, China; Key Laboratory of Industrial Biotechnology, Ministry of Education and School of Biotechnology, Jiangnan University, 1800 Lihu Road, Wuxi, Jiangsu 214122, China; Jiangsu Province Engineering Research Center of Food Synthetic Biotechnology, Jiangnan University, Wuxi 214122, China
| | - Zhimeng Wu
- Key Laboratory of Industrial Biotechnology, Ministry of Education and School of Biotechnology, Jiangnan University, 1800 Lihu Road, Wuxi, Jiangsu 214122, China.
| | - Weizhu Zeng
- Engineering Research Center of Ministry of Education on Food Synthetic Biotechnology, Jiangnan University, 1800 Lihu Road, Wuxi, Jiangsu 214122, China; Science Center for Future Foods, Jiangnan University, 1800 Lihu Road, Wuxi, Jiangsu 214122, China.
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Jungmann L, Hoffmann SL, Lang C, De Agazio R, Becker J, Kohlstedt M, Wittmann C. High-efficiency production of 5-hydroxyectoine using metabolically engineered Corynebacterium glutamicum. Microb Cell Fact 2022; 21:274. [PMID: 36578077 PMCID: PMC9798599 DOI: 10.1186/s12934-022-02003-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2022] [Accepted: 12/17/2022] [Indexed: 12/29/2022] Open
Abstract
BACKGROUND Extremolytes enable microbes to withstand even the most extreme conditions in nature. Due to their unique protective properties, the small organic molecules, more and more, become high-value active ingredients for the cosmetics and the pharmaceutical industries. While ectoine, the industrial extremolyte flagship, has been successfully commercialized before, an economically viable route to its highly interesting derivative 5-hydroxyectoine (hydroxyectoine) is not existing. RESULTS Here, we demonstrate high-level hydroxyectoine production, using metabolically engineered strains of C. glutamicum that express a codon-optimized, heterologous ectD gene, encoding for ectoine hydroxylase, to convert supplemented ectoine in the presence of sucrose as growth substrate into the desired derivative. Fourteen out of sixteen codon-optimized ectD variants from phylogenetically diverse bacterial and archaeal donors enabled hydroxyectoine production, showing the strategy to work almost regardless of the origin of the gene. The genes from Pseudomonas stutzeri (PST) and Mycobacterium smegmatis (MSM) worked best and enabled hydroxyectoine production up to 97% yield. Metabolic analyses revealed high enrichment of the ectoines inside the cells, which, inter alia, reduced the synthesis of other compatible solutes, including proline and trehalose. After further optimization, C. glutamicum Ptuf ectDPST achieved a titre of 74 g L-1 hydroxyectoine at 70% selectivity within 12 h, using a simple batch process. In a two-step procedure, hydroxyectoine production from ectoine, previously synthesized fermentatively with C. glutamicum ectABCopt, was successfully achieved without intermediate purification. CONCLUSIONS C. glutamicum is a well-known and industrially proven host, allowing the synthesis of commercial products with granted GRAS status, a great benefit for a safe production of hydroxyectoine as active ingredient for cosmetic and pharmaceutical applications. Because ectoine is already available at commercial scale, its use as precursor appears straightforward. In the future, two-step processes might provide hydroxyectoine de novo from sugar.
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Affiliation(s)
- Lukas Jungmann
- grid.11749.3a0000 0001 2167 7588Institute of Systems Biotechnology, Saarland University, Campus A1.5, Saarbrücken, Germany
| | - Sarah Lisa Hoffmann
- grid.11749.3a0000 0001 2167 7588Institute of Systems Biotechnology, Saarland University, Campus A1.5, Saarbrücken, Germany
| | - Caroline Lang
- grid.11749.3a0000 0001 2167 7588Institute of Systems Biotechnology, Saarland University, Campus A1.5, Saarbrücken, Germany
| | - Raphaela De Agazio
- grid.11749.3a0000 0001 2167 7588Institute of Systems Biotechnology, Saarland University, Campus A1.5, Saarbrücken, Germany
| | - Judith Becker
- grid.11749.3a0000 0001 2167 7588Institute of Systems Biotechnology, Saarland University, Campus A1.5, Saarbrücken, Germany
| | - Michael Kohlstedt
- grid.11749.3a0000 0001 2167 7588Institute of Systems Biotechnology, Saarland University, Campus A1.5, Saarbrücken, Germany
| | - Christoph Wittmann
- grid.11749.3a0000 0001 2167 7588Institute of Systems Biotechnology, Saarland University, Campus A1.5, Saarbrücken, Germany
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Ma Z, Wu C, Zhu L, Chang R, Ma W, Deng Y, Chen X. Bioactivity profiling of the extremolyte ectoine as a promising protectant and its heterologous production. 3 Biotech 2022; 12:331. [PMID: 36311375 PMCID: PMC9606177 DOI: 10.1007/s13205-022-03370-5] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2022] [Accepted: 09/20/2022] [Indexed: 11/28/2022] Open
Abstract
Ectoine is a compatible solutes that is diffusely dispersed in bacteria and archaea. It plays a significant role as protectant against various external pressures, such as high temperature, high osmolarity, dryness and radiation, in cells. Ectoine can be utilized in cosmetics due to its properties of moisturizing and antiultraviolet. It can also be used in the pharmaceutical industry for treating various diseases. Therefore, strong protection of ectoine creates a high commercial value. Its current market value is approximately US$1000 kg-1. However, traditional ectoine production in high-salinity media causes high costs of equipment loss and wastewater treatment. There is a growing attention to reduce the salinity of the fermentation broth without sacrificing the production of ectoine. Thus, heterologous production of ectoine in nonhalophilic microorganisms may represent the new generation of the industrial production of ectoine. In this review, we summarized and discussed the biological activities of ectoine on cell and human health protection and its heterologous production.
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Affiliation(s)
- Zhi Ma
- College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou, 310014 People’s Republic of China
| | - Chutian Wu
- College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou, 310014 People’s Republic of China
| | - Linjiang Zhu
- College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou, 310014 People’s Republic of China
| | - Renjie Chang
- College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou, 310014 People’s Republic of China
| | - Weilin Ma
- College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou, 310014 People’s Republic of China
| | - Yanfeng Deng
- College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou, 310014 People’s Republic of China
| | - Xiaolong Chen
- College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou, 310014 People’s Republic of China
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6
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Czech L, Gertzen C, Smits SHJ, Bremer E. Guilty by association: importers, exporters and
MscS
‐type mechanosensitive channels encoded in biosynthetic gene clusters for the stress‐protectant ectoine. Environ Microbiol 2022; 24:5306-5331. [DOI: 10.1111/1462-2920.16203] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2022] [Accepted: 09/07/2022] [Indexed: 11/28/2022]
Affiliation(s)
- Laura Czech
- Department of Biology, Laboratory for Microbiology and Center for Synthetic Microbiology (SYNMIKRO) Philipps‐University Marburg Marburg Germany
- Department of Chemistry and Center for Synthetic Microbiology (SYNMIKRO) Philipps‐University Marburg Marburg Germany
| | - Christoph Gertzen
- Center for Structural Studies (CSS) Heinrich‐Heine‐University Düsseldorf Düsseldorf Germany
- Institute of Pharmaceutical and Medicinal Chemistry Heinrich‐Heine‐University Düsseldorf Düsseldorf Germany
| | - Sander H. J. Smits
- Center for Structural Studies (CSS) Heinrich‐Heine‐University Düsseldorf Düsseldorf Germany
- Institute of Biochemistry Heinrich Heine University Düsseldorf Düsseldorf Germany
| | - Erhard Bremer
- Department of Biology, Laboratory for Microbiology and Center for Synthetic Microbiology (SYNMIKRO) Philipps‐University Marburg Marburg Germany
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7
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Carmona-Martínez AA, Marcos-Rodrigo E, Bordel S, Marín D, Herrero-Lobo R, García-Encina PA, Muñoz R. Elucidating the key environmental parameters during the production of ectoines from biogas by mixed methanotrophic consortia. JOURNAL OF ENVIRONMENTAL MANAGEMENT 2021; 298:113462. [PMID: 34365180 DOI: 10.1016/j.jenvman.2021.113462] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/29/2021] [Revised: 07/06/2021] [Accepted: 07/31/2021] [Indexed: 05/12/2023]
Abstract
Anaerobic digestion (AD) is a robust biotechnology for the valorisation of organic waste into biogas. However, the rapid decrease in renewable electricity prices requires alternative uses of biogas. In this context, the engineering of innovative platforms for the bio-production of chemicals from CH4 has recently emerged. The extremolyte and osmoprotectant ectoine, with a market price of ~1000€/Kg, is the industrial flagship of CH4-based bio-chemicals. This work aimed at optimizing the accumulation of ectoines using mixed microbial consortia enriched from saline environments (a salt lagoon and a salt river) and activated sludge, and biogas as feedstock. The influence of NaCl (0, 3, 6, 9 and 12 %) and Na2WO4 (0, 35 and 70 μg L-1) concentrations and incubation temperature (15, 25 and 35 °C) on the stoichiometry and kinetics of the methanotrophic consortia was investigated. Consortia enriched from activated sludge at 15 °C accumulated the highest yields of ectoine and hydroxyectoine at 6 % NaCl (105.0 ± 27.2 and 24.2 ± 5.4 mgextremolyte gbiomass-1, respectively). The consortia enriched from the salt lagoon accumulated the highest yield of ectoine and hydroxyectoine at 9 % NaCl (56.6 ± 2.5 and 51.0 ± 2.0 mgextremolyte gbiomass-1, respectively) at 25 °C. The supplementation of tungsten to the cultivation medium did not impact on the accumulation of ectoines in any of the consortia. A molecular characterization of the enrichments revealed a relative abundance of ectoine-accumulating methanotrophs of 7-16 %, with Methylomicrobium buryatense and Methylomicrobium japanense as the main players in the bioconversion of methane into ectoine.
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Affiliation(s)
- Alessandro A Carmona-Martínez
- Institute of Sustainable Processes, University of Valladolid, Dr. Mergelina s/n., Valladolid, 47011, Spain; Department of Chemical Engineering and Environmental Technology, University of Valladolid, Dr. Mergelina s/n., Valladolid, 47011, Spain
| | - Eva Marcos-Rodrigo
- Institute of Sustainable Processes, University of Valladolid, Dr. Mergelina s/n., Valladolid, 47011, Spain; Department of Chemical Engineering and Environmental Technology, University of Valladolid, Dr. Mergelina s/n., Valladolid, 47011, Spain
| | - Sergio Bordel
- Institute of Sustainable Processes, University of Valladolid, Dr. Mergelina s/n., Valladolid, 47011, Spain; Department of Chemical Engineering and Environmental Technology, University of Valladolid, Dr. Mergelina s/n., Valladolid, 47011, Spain
| | - David Marín
- Institute of Sustainable Processes, University of Valladolid, Dr. Mergelina s/n., Valladolid, 47011, Spain; Department of Chemical Engineering and Environmental Technology, University of Valladolid, Dr. Mergelina s/n., Valladolid, 47011, Spain
| | - Raquel Herrero-Lobo
- Institute of Sustainable Processes, University of Valladolid, Dr. Mergelina s/n., Valladolid, 47011, Spain; Department of Chemical Engineering and Environmental Technology, University of Valladolid, Dr. Mergelina s/n., Valladolid, 47011, Spain
| | - Pedro A García-Encina
- Institute of Sustainable Processes, University of Valladolid, Dr. Mergelina s/n., Valladolid, 47011, Spain; Department of Chemical Engineering and Environmental Technology, University of Valladolid, Dr. Mergelina s/n., Valladolid, 47011, Spain
| | - Raúl Muñoz
- Institute of Sustainable Processes, University of Valladolid, Dr. Mergelina s/n., Valladolid, 47011, Spain; Department of Chemical Engineering and Environmental Technology, University of Valladolid, Dr. Mergelina s/n., Valladolid, 47011, Spain.
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8
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Argandoña M, Piubeli F, Reina‐Bueno M, Nieto JJ, Vargas C. New insights into hydroxyectoine synthesis and its transcriptional regulation in the broad-salt growing halophilic bacterium Chromohalobacter salexigens. Microb Biotechnol 2021; 14:1472-1493. [PMID: 33955667 PMCID: PMC8313267 DOI: 10.1111/1751-7915.13799] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2020] [Revised: 02/15/2021] [Accepted: 02/28/2021] [Indexed: 11/28/2022] Open
Abstract
Elucidating the mechanisms controlling the synthesis of hydroxyectoine is important to design novel genetic engineering strategies for optimizing the production of this biotechnologically relevant compatible solute. The genome of the halophilic bacterium Chromohalobacter salexigens carries two ectoine hydroxylase genes, namely ectD and ectE, whose encoded proteins share the characteristic consensus motif of ectoine hydroxylases but showed only a 51.9% identity between them. In this work, we have shown that ectE encodes a secondary functional ectoine hydroxylase and that the hydroxyectoine synthesis mediated by this enzyme contributes to C.␣salexigens thermoprotection. The evolutionary pattern of EctD and EctE and related proteins suggests that they may have arisen from duplication of an ancestral gene preceding the directional divergence that gave origin to the orders Oceanospirillales and Alteromonadales. Osmoregulated expression of ectD at exponential phase, as well as the thermoregulated expression of ectD at the stationary phase, seemed to be dependent on the general stress factor RpoS. In contrast, expression of ectE was always RpoS-dependent regardless of the growth phase and osmotic or heat stress conditions tested. The data presented here suggest that the AraC-GlxA-like EctZ transcriptional regulator, whose encoding gene lies upstream of ectD, plays a dual function under exponential growth as both a transcriptional activator of osmoregulated ectD expression and a repressor of ectE transcription, privileging the synthesis of the main ectoine hydroxylase EctD. Inactivation of ectZ resulted in a higher amount of the total ectoines pool at the expenses of a higher accumulation of ectoine, with maintenance of the hydroxyectoine levels. In addition to the transcriptional control, our results suggest a strong post-transcriptional regulation of hydroxyectoine synthesis. Data on the accumulation of ectoine and hydroxyectoine in rpoS and ectZ strains pave the way for using these genetic backgrounds for metabolic engineering for hydroxyectoine production.
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Affiliation(s)
- Montserrat Argandoña
- Department of Microbiology and ParasitologyFaculty of PharmacyUniversity of SevillaC/ Profesor García González, 2Sevilla41012Spain
| | - Francine Piubeli
- Department of Microbiology and ParasitologyFaculty of PharmacyUniversity of SevillaC/ Profesor García González, 2Sevilla41012Spain
| | - Mercedes Reina‐Bueno
- Department of Microbiology and ParasitologyFaculty of PharmacyUniversity of SevillaC/ Profesor García González, 2Sevilla41012Spain
| | - Joaquín J. Nieto
- Department of Microbiology and ParasitologyFaculty of PharmacyUniversity of SevillaC/ Profesor García González, 2Sevilla41012Spain
| | - Carmen Vargas
- Department of Microbiology and ParasitologyFaculty of PharmacyUniversity of SevillaC/ Profesor García González, 2Sevilla41012Spain
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9
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Hermann L, Mais CN, Czech L, Smits SHJ, Bange G, Bremer E. The ups and downs of ectoine: structural enzymology of a major microbial stress protectant and versatile nutrient. Biol Chem 2021; 401:1443-1468. [PMID: 32755967 DOI: 10.1515/hsz-2020-0223] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2020] [Accepted: 07/22/2020] [Indexed: 12/13/2022]
Abstract
Ectoine and its derivative 5-hydroxyectoine are compatible solutes and chemical chaperones widely synthesized by Bacteria and some Archaea as cytoprotectants during osmotic stress and high- or low-growth temperature extremes. The function-preserving attributes of ectoines led to numerous biotechnological and biomedical applications and fostered the development of an industrial scale production process. Synthesis of ectoines requires the expenditure of considerable energetic and biosynthetic resources. Hence, microorganisms have developed ways to exploit ectoines as nutrients when they are no longer needed as stress protectants. Here, we summarize our current knowledge on the phylogenomic distribution of ectoine producing and consuming microorganisms. We emphasize the structural enzymology of the pathways underlying ectoine biosynthesis and consumption, an understanding that has been achieved only recently. The synthesis and degradation pathways critically differ in the isomeric form of the key metabolite N-acetyldiaminobutyric acid (ADABA). γ-ADABA serves as preferred substrate for the ectoine synthase, while the α-ADABA isomer is produced by the ectoine hydrolase as an intermediate in catabolism. It can serve as internal inducer for the genetic control of ectoine catabolic genes via the GabR/MocR-type regulator EnuR. Our review highlights the importance of structural enzymology to inspire the mechanistic understanding of metabolic networks at the biological scale.
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Affiliation(s)
- Lucas Hermann
- Department of Biology, Laboratory for Microbiology, Philipps-University Marburg, Karl-von Frisch Str. 8, D-35043 Marburg, Germany.,Biochemistry and Synthetic Biology of Microbial Metabolism Group, Max Planck Institute for Terrestrial Microbiology, Karl-von Frisch Str. 10, D-35043 Marburg, Germany
| | - Christopher-Nils Mais
- Center for Synthetic Microbiology (SYNMIKRO) & Faculty of Chemistry, Philipps-University Marburg, Hans-Meerwein Str. 6, D-35043 Marburg, Germany
| | - Laura Czech
- Department of Biology, Laboratory for Microbiology, Philipps-University Marburg, Karl-von Frisch Str. 8, D-35043 Marburg, Germany.,Center for Synthetic Microbiology (SYNMIKRO) & Faculty of Chemistry, Philipps-University Marburg, Hans-Meerwein Str. 6, D-35043 Marburg, Germany
| | - Sander H J Smits
- Center for Structural Studies, Heinrich Heine University Düsseldorf, Universitätsstr. 1, D-40225 Düsseldorf, Germany.,Institute of Biochemistry, Heinrich Heine University Düsseldorf, Universitätsstr. 1, D-40225 Düsseldorf, Germany
| | - Gert Bange
- Center for Synthetic Microbiology (SYNMIKRO) & Faculty of Chemistry, Philipps-University Marburg, Hans-Meerwein Str. 6, D-35043 Marburg, Germany
| | - Erhard Bremer
- Department of Biology, Laboratory for Microbiology, Philipps-University Marburg, Karl-von Frisch Str. 8, D-35043 Marburg, Germany.,Center for Synthetic Microbiology (SYNMIKRO), Philipps University Marburg, Hans-Meerwein Str. 6, D-35043 Marburg, Germany
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10
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Liu M, Liu H, Shi M, Jiang M, Li L, Zheng Y. Microbial production of ectoine and hydroxyectoine as high-value chemicals. Microb Cell Fact 2021; 20:76. [PMID: 33771157 PMCID: PMC7995798 DOI: 10.1186/s12934-021-01567-6] [Citation(s) in RCA: 50] [Impact Index Per Article: 16.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2020] [Accepted: 03/16/2021] [Indexed: 12/20/2022] Open
Abstract
Ectoine and hydroxyectoine as typical representatives of compatible solutes are not only essential for extremophiles to survive in extreme environments, but also widely used in cosmetic and medical industries. Ectoine was traditionally produced by Halomonas elongata through a "bacterial milking" process, of which the marked feature is using a high-salt medium to stimulate ectoine biosynthesis and then excreting ectoine into a low-salt medium by osmotic shock. The optimal hydroxyectoine production was achieved by optimizing the fermentation process of Halomonas salina. However, high-salinity broth exacerbates the corrosion to fermenters, and more importantly, brings a big challenge to the subsequent wastewater treatment. Therefore, increasing attention has been paid to reducing the salinity of the fermentation broth but without a sacrifice of ectoine/hydroxyectoine production. With the fast development of functional genomics and synthetic biology, quite a lot of progress on the bioproduction of ectoine/hydroxyectoine has been achieved in recent years. The importation and expression of an ectoine producing pathway in a non-halophilic chassis has so far achieved the highest titer of ectoine (~ 65 g/L), while rational flux-tuning of halophilic chassis represents a promising strategy for the next-generation of ectoine industrial production. However, efficient conversion of ectoine to hydroxyectoine, which could benefit from a clearer understanding of the ectoine hydroxylase, is still a challenge to date.
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Affiliation(s)
- Mengshuang Liu
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, No. 1 Beichen West Road, Chaoyang District, Beijing, 100101, China.,University of Chinese Academy of Sciences, Beijing, China
| | - Hui Liu
- CAS Key Laboratory of Bio-Based Materials, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, China
| | - Meng Shi
- Department of Microbiology, University of Washington, Seattle, USA
| | - Mingyue Jiang
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, No. 1 Beichen West Road, Chaoyang District, Beijing, 100101, China.,University of Chinese Academy of Sciences, Beijing, China
| | - Lingling Li
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, No. 1 Beichen West Road, Chaoyang District, Beijing, 100101, China
| | - Yanning Zheng
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, No. 1 Beichen West Road, Chaoyang District, Beijing, 100101, China.
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11
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Dong Y, Zhang H, Wang X, Ma J, Lei P, Xu H, Li S. Enhancing ectoine production by recombinant Escherichia coli through step-wise fermentation optimization strategy based on kinetic analysis. Bioprocess Biosyst Eng 2021; 44:1557-1566. [PMID: 33751211 DOI: 10.1007/s00449-021-02541-7] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2020] [Accepted: 02/16/2021] [Indexed: 12/29/2022]
Abstract
In this study, the recombinant ectoine-producing Escherichia coli ET01 was constructed by introducing the ectABC operon from Halomonas venusta ZH. To further improve ectoine production, the regulation of the fermentation process was systematically investigated. First, the effects of the initial glucose concentrations and glucose feeding mode on ectoine production were analyzed. Using a combination of pH-feedback feeding and glucose-controlled feeding, the ectoine titer reached 25.5 g/L, representing an 8.8-fold increase over standard batch culture. Then, the effects of dissolved oxygen (DO) levels (50, 40, 30, or 20%) on ectoine production were studied, and a DO control strategy was developed based on the fermentation kinetics. When the final optimized two-stage fermentation strategy was used, the ectoine titer reached 47.8 g/L, which was the highest level of ectoine produced by E. coli fermentation. The fermentation regulation strategy developed in this study might be useful for scaling up the commercial production of ectoine.
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Affiliation(s)
- Yingsheng Dong
- State Key Laboratory of Materials-Oriented Chemical Engineering, Nanjing Tech University, Nanjing, 211816, People's Republic of China
- College of Food Science and Light Industry, Nanjing Tech University, Nanjing, 211816, People's Republic of China
| | - Hao Zhang
- State Key Laboratory of Materials-Oriented Chemical Engineering, Nanjing Tech University, Nanjing, 211816, People's Republic of China
- College of Food Science and Light Industry, Nanjing Tech University, Nanjing, 211816, People's Republic of China
| | - XinYi Wang
- College of Food Science and Light Industry, Nanjing Tech University, Nanjing, 211816, People's Republic of China
| | - JunJie Ma
- College of Food Science and Light Industry, Nanjing Tech University, Nanjing, 211816, People's Republic of China
| | - Peng Lei
- College of Food Science and Light Industry, Nanjing Tech University, Nanjing, 211816, People's Republic of China
| | - Hong Xu
- State Key Laboratory of Materials-Oriented Chemical Engineering, Nanjing Tech University, Nanjing, 211816, People's Republic of China
- College of Food Science and Light Industry, Nanjing Tech University, Nanjing, 211816, People's Republic of China
- Jiangsu National Synergetic Innovation Center for Advanced Materials, Nanjing Tech University, Nanjing, People's Republic of China
| | - Sha Li
- State Key Laboratory of Materials-Oriented Chemical Engineering, Nanjing Tech University, Nanjing, 211816, People's Republic of China.
- College of Food Science and Light Industry, Nanjing Tech University, Nanjing, 211816, People's Republic of China.
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12
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Gregory GJ, Boyd EF. Stressed out: Bacterial response to high salinity using compatible solute biosynthesis and uptake systems, lessons from Vibrionaceae. Comput Struct Biotechnol J 2021; 19:1014-1027. [PMID: 33613867 PMCID: PMC7876524 DOI: 10.1016/j.csbj.2021.01.030] [Citation(s) in RCA: 33] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2020] [Revised: 01/18/2021] [Accepted: 01/20/2021] [Indexed: 12/19/2022] Open
Abstract
Bacteria have evolved mechanisms that allow them to adapt to changes in osmolarity and some species have adapted to live optimally in high salinity environments such as in the marine ecosystem. Most bacteria that live in high salinity do so by the biosynthesis and/or uptake of compatible solutes, small organic molecules that maintain the turgor pressure of the cell. Osmotic stress response mechanisms and their regulation among marine heterotrophic bacteria are poorly understood. In this review, we discuss what is known about compatible solute metabolism and transport and new insights gained from studying marine bacteria belonging to the family Vibrionaceae.
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Affiliation(s)
| | - E. Fidelma Boyd
- Corresponding author at: Department of Biological Sciences, 341 Wolf Hall, University of Delaware, Newark, DE 19716, United States.
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13
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Becker J, Wittmann C. Microbial production of extremolytes — high-value active ingredients for nutrition, health care, and well-being. Curr Opin Biotechnol 2020; 65:118-128. [DOI: 10.1016/j.copbio.2020.02.010] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2020] [Revised: 02/14/2020] [Accepted: 02/17/2020] [Indexed: 01/09/2023]
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14
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Bethlehem L, Moritz KD. Boosting Escherichia coli's heterologous production rate of ectoines by exploiting the non-halophilic gene cluster from Acidiphilium cryptum. Extremophiles 2020; 24:733-747. [PMID: 32699914 PMCID: PMC7445199 DOI: 10.1007/s00792-020-01188-8] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2020] [Accepted: 07/06/2020] [Indexed: 12/26/2022]
Abstract
The compatible solutes ectoine and hydroxyectoine are synthesized by many microorganisms as potent osmostress and desiccation protectants. Besides their successful implementation into various skincare products, they are of increasing biotechnological interest due to new applications in the healthcare sector. To meet this growing demand, efficient heterologous overproduction solutions for ectoines need to be found. This study is the first report on the utilization of the non-halophilic biosynthesis enzymes from Acidiphilium cryptum DSM 2389T for efficient heterologous production of ectoines in Escherichia coli. When grown at low salt conditions (≤ 0.5% NaCl) and utilizing the cheap carbon source glycerol, the production was characterized by the highest specific production of ectoine [2.9 g/g dry cell weight (dcw)] and hydroxyectoine (2.2 g/g dcw) reported so far and occurred at rapid specific production rates of up to 345 mg/(g dcw × h). This efficiency in production was related to an unprecedented carbon source conversion rate of approx. 60% of the theoretical maximum. These findings confirm the unique potential of the here implemented non-halophilic enzymes for ectoine production processes in E. coli and demonstrate the first efficient heterologous solution for hydroxyectoine production, as well as an extraordinary efficient low-salt ectoine production.
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Affiliation(s)
- Lukas Bethlehem
- Institute for Microbiology and Biotechnology, University Bonn, Meckenheimer Allee 168, 53115, Bonn, Germany.
| | - Katharina D Moritz
- Institute for Microbiology and Biotechnology, University Bonn, Meckenheimer Allee 168, 53115, Bonn, Germany
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15
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Contribution of mechanosensitive channels to osmoadaptation and ectoine excretion in Halomonas elongata. Extremophiles 2020; 24:421-432. [PMID: 32266565 PMCID: PMC7174268 DOI: 10.1007/s00792-020-01168-y] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2019] [Accepted: 03/24/2020] [Indexed: 12/05/2022]
Abstract
For osmoadaptation the halophilic bacterium Halomonas elongata synthesizes as its main compatible solute the aspartate derivative ectoine. H. elongata does not rely entirely on synthesis but can accumulate ectoine by uptake from the surrounding environment with the help of the osmoregulated transporter TeaABC. Disruption of the TeaABC-mediated ectoine uptake creates a strain that is constantly losing ectoine to the medium. However, the efflux mechanism of ectoine in H. elongata is not yet understood. H. elongata possesses four genes encoding mechanosensitive channels all of which belong to the small conductance type (MscS). Analysis by qRT-PCR revealed a reduction in transcription of the mscS genes with increasing salinity. The response of H. elongata to hypo- and hyperosmotic shock never resulted in up-regulation but rather in down-regulation of mscS transcription. Deletion of all four mscS genes created a mutant that was unable to cope with hypoosmotic shock. However, the knockout mutant grew significantly faster than the wildtype at high salinity of 2 M NaCl, and most importantly, still exported 80% of the ectoine compared to the wildtype. We thus conclude that a yet unknown system, which is independent of mechanosensitive channels, is the major export route for ectoine in H. elongata.
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16
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Hillier HT, Altermark B, Leiros I. The crystal structure of the tetrameric DABA-aminotransferase EctB, a rate-limiting enzyme in the ectoine biosynthesis pathway. FEBS J 2020; 287:4641-4658. [PMID: 32112674 DOI: 10.1111/febs.15265] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2019] [Revised: 01/30/2020] [Accepted: 02/26/2020] [Indexed: 01/13/2023]
Abstract
l-2,4-diaminobutyric acid (DABA) aminotransferases can catalyze the formation of amines at the distal ω-position of substrates, and is the intial and rate-limiting enzyme in the biosynthesis pathway of the cytoprotecting molecule (S)-2-methyl-1,4,5,6-tetrahydro-4-pyrimidine carboxylic acid (ectoine). Although there is an industrial interest in the biosynthesis of ectoine, the DABA aminotransferases remain poorly characterized. Herein, we present the crystal structure of EctB (2.45 Å), a DABA aminotransferase from Chromohalobacter salexigens DSM 3043, a well-studied organism with respect to osmoadaptation by ectoine biosynthesis. We investigate the enzyme's oligomeric state to show that EctB from C. salexigens is a tetramer of two functional dimers, and suggest conserved recognition sites for dimerization that also includes the characteristic gating loop that helps shape the active site of the neighboring monomer. Although ω-transaminases are known to have two binding pockets to accommodate for their dual substrate specificity, we herein provide the first description of two binding pockets in the active site that may account for the catalytic character of DABA aminotransferases. Furthermore, our biochemical data reveal that the EctB enzyme from C. salexigens is a thermostable, halotolerant enzyme with a broad pH tolerance which may be linked to its tetrameric state. Put together, this study creates a solid foundation for a deeper structural understanding of DABA aminotransferases and opening up for future downstream studies of EctB's catalytic character and its redesign as a better catalyst for ectoine biosynthesis. In summary, we believe that the EctB enzyme from C. salexigens can serve as a benchmark enzyme for characterization of DABA aminotransferases. DATABASE: Structural data are available in PDB database under the accession number 6RL5.
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Affiliation(s)
- Heidi Therese Hillier
- The Norwegian Structural Biology Centre (NorStruct), Department of Chemistry, Faculty of Science and Technology, UiT the Arctic University of Norway, Tromsø, Norway
| | - Bjørn Altermark
- The Norwegian Structural Biology Centre (NorStruct), Department of Chemistry, Faculty of Science and Technology, UiT the Arctic University of Norway, Tromsø, Norway
| | - Ingar Leiros
- The Norwegian Structural Biology Centre (NorStruct), Department of Chemistry, Faculty of Science and Technology, UiT the Arctic University of Norway, Tromsø, Norway
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17
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Czech L, Wilcken S, Czech O, Linne U, Brauner J, Smits SHJ, Galinski EA, Bremer E. Exploiting Substrate Promiscuity of Ectoine Hydroxylase for Regio- and Stereoselective Modification of Homoectoine. Front Microbiol 2019; 10:2745. [PMID: 31827466 PMCID: PMC6890836 DOI: 10.3389/fmicb.2019.02745] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2019] [Accepted: 11/12/2019] [Indexed: 11/13/2022] Open
Abstract
Extant enzymes are not only highly efficient biocatalysts for a single, or a group of chemically closely related substrates but often have retained, as a mark of their evolutionary history, a certain degree of substrate ambiguity. We have exploited the substrate ambiguity of the ectoine hydroxylase (EctD), a member of the non-heme Fe(II)-containing and 2-oxoglutarate-dependent dioxygenase superfamily, for such a task. Naturally, the EctD enzyme performs a precise regio- and stereoselective hydroxylation of the ubiquitous stress protectant and chemical chaperone ectoine (possessing a six-membered pyrimidine ring structure) to yield trans-5-hydroxyectoine. Using a synthetic ectoine derivative, homoectoine, which possesses an expanded seven-membered diazepine ring structure, we were able to selectively generate, both in vitro and in vivo, trans-5-hydroxyhomoectoine. For this transformation, we specifically used the EctD enzyme from Pseudomonas stutzeri in a whole cell biocatalyst approach, as this enzyme exhibits high catalytic efficiency not only for its natural substrate ectoine but also for homoectoine. Molecular docking approaches with the crystal structure of the Sphingopyxis alaskensis EctD protein predicted the formation of trans-5-hydroxyhomoectoine, a stereochemical configuration that we experimentally verified by nuclear-magnetic resonance spectroscopy. An Escherichia coli cell factory expressing the P. stutzeri ectD gene from a synthetic promoter imported homoectoine via the ProU and ProP compatible solute transporters, hydroxylated it, and secreted the formed trans-5-hydroxyhomoectoine, independent from all currently known mechanosensitive channels, into the growth medium from which it could be purified by high-pressure liquid chromatography.
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Affiliation(s)
- Laura Czech
- Laboratory for Microbiology, Department of Biology, Philipps-Universität Marburg, Marburg, Germany
| | - Sarah Wilcken
- Laboratory for Microbiology, Department of Biology, Philipps-Universität Marburg, Marburg, Germany
| | - Oliver Czech
- Department of Chemistry, Philipps-Universität Marburg, Marburg, Germany
| | - Uwe Linne
- Department of Chemistry, Philipps-Universität Marburg, Marburg, Germany
| | - Jarryd Brauner
- Institute of Microbiology and Biotechnology, Rheinische Friedrich-Wilhelms-Universität, Bonn, Germany
| | - Sander H J Smits
- Institute of Biochemistry, Heinrich-Heine Universität Düsseldorf, Düsseldorf, Germany.,Center for Structural Studies, Heinrich-Heine Universität Düsseldorf, Düsseldorf, Germany
| | - Erwin A Galinski
- Institute of Microbiology and Biotechnology, Rheinische Friedrich-Wilhelms-Universität, Bonn, Germany
| | - Erhard Bremer
- Laboratory for Microbiology, Department of Biology, Philipps-Universität Marburg, Marburg, Germany.,SYNMIKRO Research Center, Philipps-Universität Marburg, Marburg, Germany
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18
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Abstract
The cytoplasm of bacterial cells is a highly crowded cellular compartment that possesses considerable osmotic potential. As a result, and owing to the semipermeable nature of the cytoplasmic membrane and the semielastic properties of the cell wall, osmotically driven water influx will generate turgor, a hydrostatic pressure considered critical for growth and viability. Both increases and decreases in the external osmolarity inevitably trigger water fluxes across the cytoplasmic membrane, thus impinging on the degree of cellular hydration, molecular crowding, magnitude of turgor, and cellular integrity. Here, we assess mechanisms that permit the perception of osmotic stress by bacterial cells and provide an overview of the systems that allow them to genetically and physiologically cope with this ubiquitous environmental cue. We highlight recent developments implicating the secondary messenger c-di-AMP in cellular adjustment to osmotic stress and the role of osmotic forces in the life of bacteria-assembled in biofilms.
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Affiliation(s)
- Erhard Bremer
- Laboratory for Microbiology, Department of Biology; and Center for Synthetic Microbiology, Philipps-Universität Marburg, 35043 Marburg, Germany;
| | - Reinhard Krämer
- Institute of Biochemistry, University of Cologne, 50674 Cologne, Germany;
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19
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Bharadwaj N, Barthakur S, Biswas AD, Kumar Das M, Kour M, Ramteke A, Gogoi N. Transcript expression profiling in two contrasting cultivars and molecular cloning of a SKP-1 like gene, a component of SCF-ubiquitin proteasome system from mungbean Vigna radiate L. Sci Rep 2019; 9:8103. [PMID: 31147624 PMCID: PMC6542820 DOI: 10.1038/s41598-019-44034-4] [Citation(s) in RCA: 3] [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: 10/01/2018] [Accepted: 05/02/2019] [Indexed: 11/10/2022] Open
Abstract
Protein degradation and turnover under various environmental stresses is basically regulated by ubiquitin-proteasome system (UPS), of which SKP1 is a very essential component. Isolation and cloning of an identified potential stress responsive candidate gene SKP1, was successfully done for the first time to fathom the role of SKP1 in drought tolerance at genetic level in drought tolerant mungbean cultivar Pratap, which was screened after a detailed physio-biochemical screening amongst seven popular mungbean cultivars. The cloned gene SKP1 (accession number KX881912) is 550 bp in length, encodes 114 amino acids. It shows high sequence homology with SKP1 from Zea mays (NP_001148633). The protein expression of isolated SKP1 was confirmed by GUS fused expression using a Histochemical assay under control as well as under drought stress. Further, up-regulation in relative expression level of SKP1 in different plant parts under drought stress confirmed its utility as a potential drought responsive candidate gene certainly demanding extensive genetic research for further incorporation in breeding programs. Moreover, the structure of VrSKP1 (Vigna radiata SKP1) has been modelled, validated and an Essential Dynamics (ED) was done on the Molecular Dynamics (MD) simulation trajectories for filtering large-scale concerted motions. Free-energy calculations on the ED revealed a complex free-energy landscape (FEL) implying the conformational diversity of the modelled VrSPK1 protein.
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Affiliation(s)
- Nandita Bharadwaj
- Department of Environmental Science, Tezpur University, Tezpur, 784028, Assam, India.
| | - Sharmistha Barthakur
- ICAR-National Research Centre on Plant Biotechnology, Pusa Campus, New Delhi, 110012, India
| | - Akash Deep Biswas
- Department of Chemistry, Scuola Normale Superiore di Pisa, Piazza dei Cavalieri, 7, Pisa, 56126, Italy
| | - Monoj Kumar Das
- Department of Molecular Biology and Biotechnology, Tezpur University, Tezpur, Assam, 784028, India
| | - Manpreet Kour
- Department of Molecular Biology and Biotechnology, Tezpur University, Tezpur, Assam, 784028, India
| | - Anand Ramteke
- Department of Molecular Biology and Biotechnology, Tezpur University, Tezpur, Assam, 784028, India
| | - Nirmali Gogoi
- Department of Environmental Science, Tezpur University, Tezpur, 784028, Assam, India
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20
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Illuminating the catalytic core of ectoine synthase through structural and biochemical analysis. Sci Rep 2019; 9:364. [PMID: 30674920 PMCID: PMC6344544 DOI: 10.1038/s41598-018-36247-w] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2018] [Accepted: 11/16/2018] [Indexed: 11/26/2022] Open
Abstract
Ectoine synthase (EctC) is the signature enzyme for the production of ectoine, a compatible solute and chemical chaperone widely synthesized by bacteria as a cellular defense against the detrimental effects of osmotic stress. EctC catalyzes the last step in ectoine synthesis through cyclo-condensation of the EctA-formed substrate N-gamma-acetyl-L-2,4-diaminobutyric acid via a water elimination reaction. We have biochemically and structurally characterized the EctC enzyme from the thermo-tolerant bacterium Paenibacillus lautus (Pl). EctC is a member of the cupin superfamily and forms dimers, both in solution and in crystals. We obtained high-resolution crystal structures of the (Pl)EctC protein in forms that contain (i) the catalytically important iron, (ii) iron and the substrate N-gamma-acetyl-L-2,4-diaminobutyric acid, and (iii) iron and the enzyme reaction product ectoine. These crystal structures lay the framework for a proposal for the EctC-mediated water-elimination reaction mechanism. Residues involved in coordinating the metal, the substrate, or the product within the active site of ectoine synthase are highly conserved among a large group of EctC-type proteins. Collectively, the biochemical, mutational, and structural data reported here yielded detailed insight into the structure-function relationship of the (Pl)EctC enzyme and are relevant for a deeper understanding of the ectoine synthase family as a whole.
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21
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Czech L, Hermann L, Stöveken N, Richter AA, Höppner A, Smits SHJ, Heider J, Bremer E. Role of the Extremolytes Ectoine and Hydroxyectoine as Stress Protectants and Nutrients: Genetics, Phylogenomics, Biochemistry, and Structural Analysis. Genes (Basel) 2018; 9:genes9040177. [PMID: 29565833 PMCID: PMC5924519 DOI: 10.3390/genes9040177] [Citation(s) in RCA: 127] [Impact Index Per Article: 21.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2018] [Revised: 03/13/2018] [Accepted: 03/15/2018] [Indexed: 01/26/2023] Open
Abstract
Fluctuations in environmental osmolarity are ubiquitous stress factors in many natural habitats of microorganisms, as they inevitably trigger osmotically instigated fluxes of water across the semi-permeable cytoplasmic membrane. Under hyperosmotic conditions, many microorganisms fend off the detrimental effects of water efflux and the ensuing dehydration of the cytoplasm and drop in turgor through the accumulation of a restricted class of organic osmolytes, the compatible solutes. Ectoine and its derivative 5-hydroxyectoine are prominent members of these compounds and are synthesized widely by members of the Bacteria and a few Archaea and Eukarya in response to high salinity/osmolarity and/or growth temperature extremes. Ectoines have excellent function-preserving properties, attributes that have led to their description as chemical chaperones and fostered the development of an industrial-scale biotechnological production process for their exploitation in biotechnology, skin care, and medicine. We review, here, the current knowledge on the biochemistry of the ectoine/hydroxyectoine biosynthetic enzymes and the available crystal structures of some of them, explore the genetics of the underlying biosynthetic genes and their transcriptional regulation, and present an extensive phylogenomic analysis of the ectoine/hydroxyectoine biosynthetic genes. In addition, we address the biochemistry, phylogenomics, and genetic regulation for the alternative use of ectoines as nutrients.
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Affiliation(s)
- Laura Czech
- Laboratory for Microbiology, Department of Biology, Philipps-University Marburg, Karl-von-Frisch Str. 8, D-35043 Marburg, Germany.
| | - Lucas Hermann
- Laboratory for Microbiology, Department of Biology, Philipps-University Marburg, Karl-von-Frisch Str. 8, D-35043 Marburg, Germany.
| | - Nadine Stöveken
- Laboratory for Microbiology, Department of Biology, Philipps-University Marburg, Karl-von-Frisch Str. 8, D-35043 Marburg, Germany.
- LOEWE-Center for Synthetic Microbiology, Philipps-University Marburg, Hans-Meerwein Str. 6, D-35043 Marburg, Germany.
| | - Alexandra A Richter
- Laboratory for Microbiology, Department of Biology, Philipps-University Marburg, Karl-von-Frisch Str. 8, D-35043 Marburg, Germany.
| | - Astrid Höppner
- Center for Structural Studies, Heinrich-Heine University Düsseldorf, Universitäts Str. 1, D-40225 Düsseldorf, Germany.
| | - Sander H J Smits
- Center for Structural Studies, Heinrich-Heine University Düsseldorf, Universitäts Str. 1, D-40225 Düsseldorf, Germany.
- Institute of Biochemistry, Heinrich-Heine University Düsseldorf, Universitäts Str. 1, D-40225 Düsseldorf, Germany.
| | - Johann Heider
- Laboratory for Microbiology, Department of Biology, Philipps-University Marburg, Karl-von-Frisch Str. 8, D-35043 Marburg, Germany.
- LOEWE-Center for Synthetic Microbiology, Philipps-University Marburg, Hans-Meerwein Str. 6, D-35043 Marburg, Germany.
| | - Erhard Bremer
- Laboratory for Microbiology, Department of Biology, Philipps-University Marburg, Karl-von-Frisch Str. 8, D-35043 Marburg, Germany.
- LOEWE-Center for Synthetic Microbiology, Philipps-University Marburg, Hans-Meerwein Str. 6, D-35043 Marburg, Germany.
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22
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Tinkering with Osmotically Controlled Transcription Allows Enhanced Production and Excretion of Ectoine and Hydroxyectoine from a Microbial Cell Factory. Appl Environ Microbiol 2018; 84:AEM.01772-17. [PMID: 29101191 DOI: 10.1128/aem.01772-17] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2017] [Accepted: 10/28/2017] [Indexed: 12/21/2022] Open
Abstract
Ectoine and hydroxyectoine are widely synthesized by members of the Bacteria and a few members of the Archaea as potent osmostress protectants. We have studied the salient features of the osmostress-responsive promoter directing the transcription of the ectoine/hydroxyectoine biosynthetic gene cluster from the plant-root-associated bacterium Pseudomonas stutzeri by transferring it into Escherichia coli, an enterobacterium that does not produce ectoines naturally. Using ect-lacZ reporter fusions, we found that the heterologous ect promoter reacted with exquisite sensitivity in its transcriptional profile to graded increases in sustained high salinity, responded to a true osmotic signal, and required the buildup of an osmotically effective gradient across the cytoplasmic membrane for its induction. The involvement of the -10, -35, and spacer regions of the sigma-70-type ect promoter in setting promoter strength and response to osmotic stress was assessed through site-directed mutagenesis. Moderate changes in the ect promoter sequence that increase its resemblance to housekeeping sigma-70-type promoters of E. coli afforded substantially enhanced expression, both in the absence and in the presence of osmotic stress. Building on this set of ect promoter mutants, we engineered an E. coli chassis strain for the heterologous production of ectoines. This synthetic cell factory lacks the genes for the osmostress-responsive synthesis of trehalose and the compatible solute importers ProP and ProU, and it continuously excretes ectoines into the growth medium. By combining appropriate host strains and different plasmid variants, excretion of ectoine, hydroxyectoine, or a mixture of both compounds was achieved under mild osmotic stress conditions.IMPORTANCE Ectoines are compatible solutes, organic osmolytes that are used by microorganisms to fend off the negative consequences of high environmental osmolarity on cellular physiology. An understanding of the salient features of osmostress-responsive promoters directing the expression of the ectoine/hydroxyectoine biosynthetic gene clusters is lacking. We exploited the ect promoter from an ectoine/hydroxyectoine-producing soil bacterium for such a study by transferring it into a surrogate bacterial host. Despite the fact that E. coli does not synthesize ectoines naturally, the ect promoter retained its exquisitely sensitive osmotic control, indicating that osmoregulation of ect transcription is an inherent feature of the promoter and its flanking sequences. These sequences were narrowed to a 116-bp DNA fragment. Ectoines have interesting commercial applications. Building on data from a site-directed mutagenesis study of the ect promoter, we designed a synthetic cell factory that secretes ectoine, hydroxyectoine, or a mixture of both compounds into the growth medium.
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Hoffmann T, Bremer E. Guardians in a stressful world: the Opu family of compatible solute transporters from Bacillus subtilis. Biol Chem 2017; 398:193-214. [PMID: 27935846 DOI: 10.1515/hsz-2016-0265] [Citation(s) in RCA: 43] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2016] [Accepted: 08/29/2016] [Indexed: 01/09/2023]
Abstract
The development of a semi-permeable cytoplasmic membrane was a key event in the evolution of microbial proto-cells. As a result, changes in the external osmolarity will inevitably trigger water fluxes along the osmotic gradient. The ensuing osmotic stress has consequences for the magnitude of turgor and will negatively impact cell growth and integrity. No microorganism can actively pump water across the cytoplasmic membrane; hence, microorganisms have to actively adjust the osmotic potential of their cytoplasm to scale and direct water fluxes in order to prevent dehydration or rupture. They will accumulate ions and physiologically compliant organic osmolytes, the compatible solutes, when they face hyperosmotic conditions to retain cell water, and they rapidly expel these compounds through the transient opening of mechanosensitive channels to curb water efflux when exposed to hypo-osmotic circumstances. Here, we provide an overview on the salient features of the osmostress response systems of the ubiquitously distributed bacterium Bacillus subtilis with a special emphasis on the transport systems and channels mediating regulation of cellular hydration and turgor under fluctuating osmotic conditions. The uptake of osmostress protectants via the Opu family of transporters, systems of central importance for the management of osmotic stress by B. subtilis, will be particularly highlighted.
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