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Nakayama Y, Rohde PR, Martinac B. "Force-From-Lipids" Dependence of the MscCG Mechanosensitive Channel Gating on Anionic Membranes. Microorganisms 2023; 11:microorganisms11010194. [PMID: 36677485 PMCID: PMC9861469 DOI: 10.3390/microorganisms11010194] [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: 12/22/2022] [Revised: 01/04/2023] [Accepted: 01/05/2023] [Indexed: 01/15/2023] Open
Abstract
Mechanosensory transduction in Corynebacterium glutamicum plays a major role in glutamate efflux for industrial MSG, whose production depends on the activation of MscCG-type mechanosensitive channels. Dependence of the MscCG channel activation by membrane tension on the membrane lipid content has to date not been functionally characterized. Here, we report the MscCG channel patch clamp recording from liposomes fused with C. glutamicum membrane vesicles as well as from proteoliposomes containing the purified MscCG protein. Our recordings demonstrate that mechanosensitivity of MscCG channels depends significantly on the presence of negatively charged lipids in the proteoliposomes. MscCG channels in liposome preparations fused with native membrane vesicles exhibited the activation threshold similar to the channels recorded from C. glutamicum giant spheroplasts. In comparison, the activation threshold of the MscCG channels reconstituted into azolectin liposomes was higher than the activation threshold of E. coli MscL, which is gated by membrane tension close to the bilayer lytic tension. The spheroplast-like activation threshold was restored when the MscCG channels were reconstituted into liposomes made of E. coli polar lipid extract. In liposomes made of polar lipids mixed with synthetic phosphatidylethanolamine, phosphatidylglycerol, and cardiolipin, the activation threshold of MscCG was significantly reduced compared to the activation threshold recorded in azolectin liposomes, which suggests the importance of anionic lipids for the channel mechanosensitivity. Moreover, the micropipette aspiration technique combined with patch fluorometry demonstrated that membranes containing anionic phosphatidylglycerol are softer than membranes containing only polar non-anionic phosphatidylcholine and phosphatidylethanolamine. The difference in mechanosensitivity between C. glutamicum MscCG and canonical MscS of E. coli observed in proteoliposomes explains the evolutionary tuning of the force from lipids sensing in various bacterial membrane environments.
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Affiliation(s)
- Yoshitaka Nakayama
- Molecular Cardiology and Biophysics Division, Victor Chang Cardiac Research Institute, Sydney 2010, Australia
- Faculty of Medicine, St Vincent’s Clinical School, The University of New South Wales, Sydney 2010, Australia
| | - Paul R. Rohde
- Molecular Cardiology and Biophysics Division, Victor Chang Cardiac Research Institute, Sydney 2010, Australia
| | - Boris Martinac
- Molecular Cardiology and Biophysics Division, Victor Chang Cardiac Research Institute, Sydney 2010, Australia
- Faculty of Medicine, St Vincent’s Clinical School, The University of New South Wales, Sydney 2010, Australia
- Correspondence: ; Tel.: +61-2-9295-8743
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2
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Nie Z, Liu P, Wang Y, Guo X, Tan Z, Shen J, Tang Z, Lin J, Sun J, Zheng P, Zhu L. Directed Evolution and Rational Design of Mechanosensitive Channel MscCG2 for Improved Glutamate Excretion Efficiency. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2021; 69:15660-15669. [PMID: 34928605 DOI: 10.1021/acs.jafc.1c07086] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Mechanosensitive amino acid exporters have drawn increasing attention due to their important roles in extracellular accumulation of the target amino acids. Protein engineering is a powerful approach to tailor the properties of amino acid exporters and illustrate structure-function relationships. Here we report the first protein engineering effort on the mechanosensitive glutamate exporter MscCG2 from Corynebacterium glutamicum for improved excretion efficiency of glutamate and understanding of the structure-function relationship. MscCG2 was engineered through directed evolution and computer-assisted design with a coupled assay in microtiter plate format. Improved MscCG2 variants were identified with up to 2.5-fold increase in the level of glutamate excretion in the early stage of fermentation and 1.5-fold in the late stage of fermentation under experimental conditions. Furthermore, the identified variants exhibited enhanced efflux of 4-fluoroglutamate (4-FG), an analog of glutamate. Structure analysis employing homology modeling and molecular dynamics (MD) simulation reveal that identified amino acid substitutions enlarge the size of the seven portals on the equator of MscCG2 and expand the narrowest rim of its inner channel, respectively. This study demonstrates the great potential of protein engineering in improving the secretion efficiency of exporters for enhanced bioproduction.
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Affiliation(s)
- Zhihua Nie
- Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin 300308, China
- National Technology Innovation Center of Synthetic Biology, Tianjin 300308, China
| | - Pi Liu
- Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin 300308, China
- National Technology Innovation Center of Synthetic Biology, Tianjin 300308, China
| | - Yu Wang
- Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin 300308, China
- National Technology Innovation Center of Synthetic Biology, Tianjin 300308, China
| | - Xuan Guo
- Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin 300308, China
- National Technology Innovation Center of Synthetic Biology, Tianjin 300308, China
| | - Zijian Tan
- Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin 300308, China
- National Technology Innovation Center of Synthetic Biology, Tianjin 300308, China
| | - Jie Shen
- Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin 300308, China
- National Technology Innovation Center of Synthetic Biology, Tianjin 300308, China
| | - Zijing Tang
- Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin 300308, China
- National Technology Innovation Center of Synthetic Biology, Tianjin 300308, China
| | - Jianping Lin
- Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin 300308, China
- National Technology Innovation Center of Synthetic Biology, Tianjin 300308, China
| | - Jibin Sun
- Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin 300308, China
- National Technology Innovation Center of Synthetic Biology, Tianjin 300308, China
| | - Ping Zheng
- Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin 300308, China
- National Technology Innovation Center of Synthetic Biology, Tianjin 300308, China
| | - Leilei Zhu
- Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin 300308, China
- National Technology Innovation Center of Synthetic Biology, Tianjin 300308, China
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3
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Ogata S, Hirasawa T. Induction of glutamic acid production by copper in Corynebacterium glutamicum. Appl Microbiol Biotechnol 2021; 105:6909-6920. [PMID: 34463802 DOI: 10.1007/s00253-021-11516-3] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2021] [Revised: 08/09/2021] [Accepted: 08/10/2021] [Indexed: 11/28/2022]
Abstract
From the previous transcriptome analysis (Hirasawa et al. Biotechnol J 13:e1700612, 2018), it was found that expression of genes whose expression is regulated by stress-responsive transcriptional regulators was altered during penicillin-induced glutamic acid production in Corynebacterium glutamicum. Therefore, we investigated whether stress treatments, such as copper and iron addition, could induce glutamic acid production in C. glutamicum and found that the addition of copper did induce glutamic acid production in this species. Moreover, we also determined that glutamic acid production levels upon copper addition in a gain-of-function mutant strain of the mechanosensitive channel, NCgl1221, involved in glutamic acid export, were comparable to glutamic acid levels produced upon penicillin addition and biotin limitation in the wild-type strain. Furthermore, disruption of the odhI gene, which encodes a protein responsible for the decreased activity of the 2-oxoglutarate dehydrogenase complex during glutamic acid production, significantly diminished glutamic acid production induced by copper. These results indicate that copper can induce glutamic acid production and this induction requires OdhI like biotin limitation and penicillin addition, but a gain-of-function mutation in the NCgl1221 mechanosensitive channel is necessary for its high-level glutamic acid production. However, a significant increase in odhI transcription was not observed with copper addition in both wild-type and NCgl1221 gain-of-function mutant strains. In addition, disruption of the csoR gene encoding a copper-responsive transcriptional repressor enhanced copper-induced glutamic acid production in the NCgl1221 gain-of-function mutant, indicating that unidentified CsoR-regulated genes may contribute to copper-induced glutamic acid production in C. glutamicum. KEY POINTS: • Copper can induce glutamic acid production by Corynebacterium glutamicum. • Copper-induced glutamic acid production requires OdhI protein. • Copper-induced glutamic acid production requires a gain-of-function mutation in the mechanosensitive channel NCgl1221, which is responsible for the production of glutamic acid.
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Affiliation(s)
- Shunsuke Ogata
- School of Life Science and Technology, Tokyo Institute of Technology, 4250 Nagatsuta-cho, Midori-ku, Yokohama, Kanagawa, 226-8501, Japan
| | - Takashi Hirasawa
- School of Life Science and Technology, Tokyo Institute of Technology, 4250 Nagatsuta-cho, Midori-ku, Yokohama, Kanagawa, 226-8501, Japan.
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4
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Nakayama Y. Corynebacterium glutamicum Mechanosensing: From Osmoregulation to L-Glutamate Secretion for the Avian Microbiota-Gut-Brain Axis. Microorganisms 2021; 9:201. [PMID: 33478007 PMCID: PMC7835871 DOI: 10.3390/microorganisms9010201] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2020] [Revised: 01/15/2021] [Accepted: 01/18/2021] [Indexed: 12/18/2022] Open
Abstract
After the discovery of Corynebacterium glutamicum from avian feces-contaminated soil, its enigmatic L-glutamate secretion by corynebacterial MscCG-type mechanosensitive channels has been utilized for industrial monosodium glutamate production. Bacterial mechanosensitive channels are activated directly by increased membrane tension upon hypoosmotic downshock; thus; the physiological significance of the corynebacterial L-glutamate secretion has been considered as adjusting turgor pressure by releasing cytoplasmic solutes. In this review, we present information that corynebacterial mechanosensitive channels have been evolutionally specialized as carriers to secrete L-glutamate into the surrounding environment in their habitats rather than osmotic safety valves. The lipid modulation activation of MscCG channels in L-glutamate production can be explained by the "Force-From-Lipids" and "Force-From-Tethers" mechanosensing paradigms and differs significantly from mechanical activation upon hypoosmotic shock. The review also provides information on the search for evidence that C. glutamicum was originally a gut bacterium in the avian host with the aim of understanding the physiological roles of corynebacterial mechanosensing. C. glutamicum is able to secrete L-glutamate by mechanosensitive channels in the gut microbiota and help the host brain function via the microbiota-gut-brain axis.
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Affiliation(s)
- Yoshitaka Nakayama
- Molecular Cardiology and Biophysics Division, Victor Chang Cardiac Research Institute, Darlinghurst, NSW 2010, Australia; ; Tel.: +61-2-9295-8744
- St Vincent’s Clinical School, Faculty of Medicine, The University of New South Wales, Darlinghurst, NSW 2010, Australia
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Kawasaki H, Martinac B. Mechanosensitive channels of Corynebacterium glutamicum functioning as exporters of l-glutamate and other valuable metabolites. Curr Opin Chem Biol 2020; 59:77-83. [DOI: 10.1016/j.cbpa.2020.05.005] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2020] [Revised: 05/09/2020] [Accepted: 05/17/2020] [Indexed: 01/06/2023]
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6
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Xiao J, Wang D, Wang L, Jiang Y, Xue L, Sui S, Wang J, Guo C, Wang R, Wang J, Li N, Fan H, Lv M. Increasing L-lysine production in Corynebacterium glutamicum by engineering amino acid transporters. Amino Acids 2020; 52:1363-1374. [PMID: 33021685 DOI: 10.1007/s00726-020-02893-6] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2020] [Accepted: 09/17/2020] [Indexed: 12/28/2022]
Abstract
Corynebacterium glutamicum has a long and successful history in the biotechnological production of L-lysine. Besides the adjustment of metabolic pathways, intracellular and extracellular transport systems are critical for the cellular metabolism of L-lysine or its by-products. Here, three amino acid transmembrane transporters, namely, GluE, BrnE/BrnF, and LysP, which are widely present in C. glutamicum strains, were each investigated by gene knockout. In comparison with that in the wild-type strain, the yield of L-lysine increased by 9.0%, 12.3%, and 10.0% after the deletion of the gluE, brnE/brnF, and lysP genes, respectively, in C. glutamicum 23,604. Moreover, the amount of by-product amino acids decreased significantly when the gluE and brnE/brnF genes were deleted. It was also demonstrated that there was no effect on the growth of the strain when the gluE or lysP gene was deleted, whereas the biomass of C. glutamicum WL1702 (ΔbrnE/ΔbrnF) in the fermentation medium was significantly reduced in comparison with that of the wild type. These results also provide useful information for enhancing the production of L-lysine or other amino acids by C. glutamicum.
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Affiliation(s)
- Jing Xiao
- State Key Laboratory of Biobased Material and Green Papermaking (LBMP), Qilu University of Technology), Jinan, 250353, Shandong, People's Republic of China
| | - Datao Wang
- State Key Laboratory of Biobased Material and Green Papermaking (LBMP), Qilu University of Technology), Jinan, 250353, Shandong, People's Republic of China
| | - Lei Wang
- School of Biotechnology, Jiangnan University, 1800 Lihu Road, Wuxi, 214122, Jiangsu, People's Republic of China
| | - Yanjun Jiang
- State Key Laboratory of Biobased Material and Green Papermaking (LBMP), Qilu University of Technology), Jinan, 250353, Shandong, People's Republic of China
| | - Le Xue
- State Key Laboratory of Biobased Material and Green Papermaking (LBMP), Qilu University of Technology), Jinan, 250353, Shandong, People's Republic of China
| | - Songsen Sui
- Zhucheng Dongxiao Biotechnology Co., Ltd, Xinxing Town, Zhucheng, 262200, Shandong, People's Republic of China
| | - Jianbin Wang
- Zhucheng Dongxiao Biotechnology Co., Ltd, Xinxing Town, Zhucheng, 262200, Shandong, People's Republic of China
| | - Chuanzhuang Guo
- Zhucheng Dongxiao Biotechnology Co., Ltd, Xinxing Town, Zhucheng, 262200, Shandong, People's Republic of China
| | - Ruiming Wang
- State Key Laboratory of Biobased Material and Green Papermaking (LBMP), Qilu University of Technology), Jinan, 250353, Shandong, People's Republic of China
| | - Junqing Wang
- State Key Laboratory of Biobased Material and Green Papermaking (LBMP), Qilu University of Technology), Jinan, 250353, Shandong, People's Republic of China.
| | - Nan Li
- College of Biotechnology, Tianjin University of Science and Technology, Tianjin, 300457, People's Republic of China.
| | - Han Fan
- State Key Laboratory of Biobased Material and Green Papermaking (LBMP), Qilu University of Technology), Jinan, 250353, Shandong, People's Republic of China
| | - Maocui Lv
- State Key Laboratory of Biobased Material and Green Papermaking (LBMP), Qilu University of Technology), Jinan, 250353, Shandong, People's Republic of China
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Huang M, Zhao Y, Li R, Huang W, Chen X. Improvement of l-arginine production by in silico genome-scale metabolic network model guided genetic engineering. 3 Biotech 2020; 10:126. [PMID: 32140378 DOI: 10.1007/s13205-020-2114-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2019] [Accepted: 02/02/2020] [Indexed: 12/12/2022] Open
Abstract
Genome-scale metabolic network model (GSMM) is an important in silico tool that can efficiently predict the target genes to be modulated. A Corynebacterium crenatum argB-M4 Cc_iKK446_arginine model was constructed on the basis of the GSMM of Corynebacterium glutamicum ATCC 13032 Cg_iKK446. Sixty-four gene deletion sites, twenty-four gene enhancement sites, and seven gene attenuation sites were determined for the improvement of l-arginine production in engineered C. crenatum. Among these sites, the effects of disrupting putP, cgl2310, pta, and Ncgl1221 and overexpressing lysE on l-arginine production were investigated. Moreover, the strain CCM007 with deleted putP, cgl2310, pta, and Ncgl1221 and overexpressed lysE produced 24.85 g/L l-arginine. This finding indicated a 106.8% improvement in l-arginine production compared with that in CCM01. GSMM is an excellent tool for identifying target genes to promote l-arginine accumulation in engineered C. crenatum.
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Affiliation(s)
- Mingzhu Huang
- 1Department of Life Science, Jiangxi Normal University, Nanchang, 330096 People's Republic of China
- 2School of Life Science, Key Laboratory of Functional Small Organic Molecule of Ministry of Education, Jiangxi Normal University, 99 Ziyang Road, Nanchang, 330096 People's Republic of China
| | - Yue Zhao
- 1Department of Life Science, Jiangxi Normal University, Nanchang, 330096 People's Republic of China
| | - Rong Li
- 1Department of Life Science, Jiangxi Normal University, Nanchang, 330096 People's Republic of China
| | - Weihua Huang
- 1Department of Life Science, Jiangxi Normal University, Nanchang, 330096 People's Republic of China
| | - Xuelan Chen
- 1Department of Life Science, Jiangxi Normal University, Nanchang, 330096 People's Republic of China
- 2School of Life Science, Key Laboratory of Functional Small Organic Molecule of Ministry of Education, Jiangxi Normal University, 99 Ziyang Road, Nanchang, 330096 People's Republic of China
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8
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Krumbach K, Sonntag CK, Eggeling L, Marienhagen J. CRISPR/Cas12a Mediated Genome Editing To Introduce Amino Acid Substitutions into the Mechanosensitive Channel MscCG of Corynebacterium glutamicum. ACS Synth Biol 2019; 8:2726-2734. [PMID: 31790583 PMCID: PMC6994057 DOI: 10.1021/acssynbio.9b00361] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
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Against the background of a growing demand for the implementation
of environmentally friendly production processes, microorganisms are
engineered for the large-scale biosynthesis of chemicals, fuels, or
food and feed additives from sustainable resources. Since strain development
is expensive and time-consuming, continuous improvement of molecular
tools for the genetic modification of the microbial production hosts
is absolutely vital. Recently, the CRISPR/Cas12a technology for the
engineering of Corynebacterium glutamicum as an important
platform organism for industrial amino acid production has been introduced.
Here, this system was advanced by designing an easy-to-construct crRNA
delivery vector using simple oligonucleotides. In combination with
a C. glutamicum strain engineered for the chromosomal
expression of the β-galactosidase-encoding lacZ gene, this new plasmid was used to investigate CRISPR/Cas12a targeting
and editing at various positions relative to the PAM site. Finally,
we used this system to perform codon saturation mutagenesis at critical
positions in the mechanosensitive channel MscCG to identify new gain-of-function
mutations for increased l-glutamate export. The mutations
obtained can be explained by particular demands of the channel on
its immediate lipid environment to allow l-glutamate efflux.
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Affiliation(s)
- Karin Krumbach
- Institute of Bio- and Geosciences, IBG-1: Biotechnology, Forschungszentrum Jülich, D-52425 Jülich, Germany
| | | | - Lothar Eggeling
- Institute of Bio- and Geosciences, IBG-1: Biotechnology, Forschungszentrum Jülich, D-52425 Jülich, Germany
| | - Jan Marienhagen
- Institute of Bio- and Geosciences, IBG-1: Biotechnology, Forschungszentrum Jülich, D-52425 Jülich, Germany
- Institute of Biotechnology, RWTH Aachen University, Worringer Weg 3, D-52074 Aachen, Germany
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Wen J, Bao J. Engineering Corynebacterium glutamicum triggers glutamic acid accumulation in biotin-rich corn stover hydrolysate. BIOTECHNOLOGY FOR BIOFUELS 2019; 12:86. [PMID: 31011369 PMCID: PMC6463653 DOI: 10.1186/s13068-019-1428-5] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/10/2019] [Accepted: 04/08/2019] [Indexed: 05/22/2023]
Abstract
BACKGROUND Lignocellulose biomass contains high amount of biotin and resulted in an excessive biotin condition for cellulosic glutamic acid accumulation by Corynebacterium glutamicum. Penicillin or ethambutol triggers cellulosic glutamic acid accumulation, but they are not suitable for practical use due to the fermentation instability and environmental concerns. Efficient glutamic acid production from lignocellulose feedstocks should be achieved without any chemical inductions. RESULTS An industrial strain C. glutamicum S9114 was metabolically engineered to achieve efficient glutamic acid accumulation in biotin-excessive corn stover hydrolysate. Among the multiple metabolic engineering efforts, two pathway regulations effectively triggered the glutamic acid accumulation in lignocellulose hydrolysate. The C-terminal truncation of glutamate secretion channel MscCG (ΔC110) led to the successful glutamic acid secretion in corn stover hydrolysate without inductions. Then the α-oxoglutarate dehydrogenase complex (ODHC) activity was attenuated by regulating odhA RBS sequence, and glutamic acid accumulation was further elevated for more than fivefolds. The obtained C. glutamicum XW6 strain reached a record-high titer of 65.2 g/L with the overall yield of 0.63 g/g glucose using corn stover as the starting feedstock without any chemical induction. CONCLUSIONS Metabolic engineering method was successfully applied to achieve efficient glutamic acid in biotin-rich lignocellulose hydrolysate for the first time. This study demonstrated the high potential of glutamic acid production from lignocellulose feedstock.
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Affiliation(s)
- Jingbai Wen
- State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, 130 Meilong Road, Shanghai, 200237 China
| | - Jie Bao
- State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, 130 Meilong Road, Shanghai, 200237 China
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A Novel Corynebacterium glutamicum l-Glutamate Exporter. Appl Environ Microbiol 2018; 84:AEM.02691-17. [PMID: 29330181 DOI: 10.1128/aem.02691-17] [Citation(s) in RCA: 41] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2017] [Accepted: 01/07/2018] [Indexed: 01/24/2023] Open
Abstract
Besides metabolic pathways and regulatory networks, transport systems are also pivotal for cellular metabolism and hyperproduction of biochemicals using microbial cell factories. The identification and characterization of transporters are therefore of great significance for the understanding and engineering of transport reactions. Herein, a novel l-glutamate exporter, MscCG2, which exists extensively in Corynebacterium glutamicum strains but is distinct from the only known l-glutamate exporter, MscCG, was discovered in an industrial l-glutamate-producing C. glutamicum strain. MscCG2 was predicted to possess three transmembrane helices in the N-terminal region and located in the cytoplasmic membrane, which are typical structural characteristics of the mechanosensitive channel of small conductance. MscCG2 has a low amino acid sequence identity (23%) to MscCG and evolved separately from MscCG with four transmembrane helices. Despite the considerable differences between MscCG2 and MscCG in sequence and structure, gene deletion and complementation confirmed that MscCG2 also functioned as an l-glutamate exporter and an osmotic safety valve in C. glutamicum Besides, transcriptional analysis showed that MscCG2 and MscCG genes were transcribed in similar patterns and not induced by l-glutamate-producing conditions. It was also demonstrated that MscCG2-mediated l-glutamate excretion was activated by biotin limitation or penicillin treatment and that constitutive l-glutamate excretion was triggered by a gain-of-function mutation of MscCG2 (A151V). Discovery of MscCG2 will enrich the understanding of bacterial amino acid transport and provide additional targets for exporter engineering.IMPORTANCE The exchange of matter, energy, and information with surroundings is fundamental for cellular metabolism. Therefore, studying transport systems that are essential for these processes is of great significance. Besides, transport systems of bacterial cells are usually related to product excretion as well as product reuptake, making transporter engineering a useful strategy for strain improvement. The significance of our research is in identifying and characterizing a novel l-glutamate exporter from the industrial workhorse Corynebacterium glutamicum, which will enrich the understanding of l-glutamate excretion and provide a new target for studying bacterial amino acid transport and engineering transport reactions.
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Abstract
Mechanosensitive (MS) channels protect bacteria against hypo-osmotic shock and fulfil additional functions. Hypo-osmotic shock leads to high turgor pressure that can cause cell rupture and death. MS channels open under these conditions and release unspecifically solutes and consequently the turgor pressure. They can recognise the raised pressure via the increased tension in the cell membrane. Currently, a better understanding how MS channels can sense tension on molecular level is developing because the interaction of the lipid bilayer with the channel is being investigated in detail. The MS channel of large conductance (MscL) and of small conductance (MscS) have been distinguished and studied in molecular detail. In addition, larger channels were found that contain a homologous region corresponding to MscS so that MscS represents a family of channels. Often several members of this family are present in a species. The importance of this family is underlined by the fact that members can be found not only in bacteria but also in higher organisms. While MscL and MscS have been studied for years in particular by electrophysiology, mutagenesis, molecular dynamics, X-ray crystallography and other biophysical techniques, only recently more details are emerging about other members of the MscS-family.
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Hirasawa T, Shimizu H. Glutamic Acid Fermentation: Discovery of Glutamic Acid-Producing Microorganisms, Analysis of the Production Mechanism, Metabolic Engineering, and Industrial Production Process. Ind Biotechnol (New Rochelle N Y) 2016. [DOI: 10.1002/9783527807833.ch11] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Affiliation(s)
- Takashi Hirasawa
- Tokyo Institute of Technology; School of Life Science and Technology; 4259 Nagatsuta-cho, Midori-ku Yokohama Kanagawa 226-8501 Japan
| | - Hiroshi Shimizu
- Osaka University; Department of Bioinformatic Engineering, Graduate School of Information Science and Technology; 1-5 Yamadaoka Suita Osaka 565-0871 Japan
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13
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Recent advances in amino acid production by microbial cells. Curr Opin Biotechnol 2016; 42:133-146. [PMID: 27151315 DOI: 10.1016/j.copbio.2016.04.017] [Citation(s) in RCA: 71] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2016] [Revised: 04/14/2016] [Accepted: 04/15/2016] [Indexed: 12/25/2022]
Abstract
Amino acids have been utilized for the production of foods, animal feeds and pharmaceuticals. After the discovery of the glutamic acid-producing bacterium Corynebacterium glutamicum by Japanese researchers, the production of amino acids, which are primary metabolites, has been achieved using various microbial cells as hosts. Recently, metabolic engineering studies on the rational design of amino acid-producing microbial cells have been successfully conducted. Moreover, the technology of systems biology has been applied to metabolic engineering for the creation of amino acid-producing microbial cells. Currently, new technologies including synthetic biology, single-cell analysis, and evolutionary engineering have been utilized to create amino acid-producing microbial cells. In addition, useful compounds from amino acids have been produced by microbial cells. Here, current researches into the metabolic engineering of microbial cells toward production of amino acids and amino acid-related compounds are reviewed.
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14
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Suzuki S, Nanatani K, Abe K. R76 in transmembrane domain 3 of the aspartate:alanine transporter AspT is involved in substrate transport. Biosci Biotechnol Biochem 2016; 80:744-7. [PMID: 26849958 DOI: 10.1080/09168451.2015.1123609] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
The L-aspartate:L-alanine antiporter of Tetragenococcus halophilus (AspT) possesses an arginine residue (R76) within the GxxxG motif in the central part of transmembrane domain 3 (TM3)-a residue that has been estimated to transport function. In this study, we carried out amino acid substitutions of R76 and used proteoliposome reconstitution for analyzing the transport function of each substitution. Both l-aspartate and l-alanine transport assays showed that R76K has higher activity than the AspT-WT (R76), whereas R76D and R76E have lower activity than the AspT-WT. These results suggest that R76 is involved in AspT substrate transport.
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Affiliation(s)
- Satomi Suzuki
- a Department of Microbial Biotechnology , Graduate School of Agricultural Science, Tohoku University , Sendai , Japan
| | - Kei Nanatani
- a Department of Microbial Biotechnology , Graduate School of Agricultural Science, Tohoku University , Sendai , Japan
| | - Keietsu Abe
- a Department of Microbial Biotechnology , Graduate School of Agricultural Science, Tohoku University , Sendai , Japan
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15
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Hirasawa T, Wachi M. Glutamate Fermentation-2: Mechanism of L-Glutamate Overproduction in Corynebacterium glutamicum. ADVANCES IN BIOCHEMICAL ENGINEERING/BIOTECHNOLOGY 2016; 159:57-72. [PMID: 27913829 DOI: 10.1007/10_2016_26] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
The nonpathogenic coryneform bacterium, Corynebacterium glutamicum, was isolated as an L-glutamate-overproducing microorganism by Japanese researchers and is currently utilized in various amino acid fermentation processes. L-Glutamate production by C. glutamicum is induced by limitation of biotin and addition of fatty acid ester surfactants and β-lactam antibiotics. These treatments affect the cell surface structures of C. glutamicum. After the discovery of C. glutamicum, many researchers have investigated the underlying mechanism of L-glutamate overproduction with respect to the cell surface structures of this organism. Furthermore, metabolic regulation during L-glutamate overproduction by C. glutamicum, particularly, the relationship between central carbon metabolism and L-glutamate biosynthesis, has been investigated. Recently, the role of a mechanosensitive channel protein in L-glutamate overproduction has been reported. In this chapter, mechanisms of L-glutamate overproduction by C. glutamicum have been reviewed.
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Affiliation(s)
- Takashi Hirasawa
- Department of Life Science and Technology, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama, 226-8501, Japan
| | - Masaaki Wachi
- Department of Life Science and Technology, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama, 226-8501, Japan.
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16
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The impact of the C-terminal domain on the gating properties of MscCG from Corynebacterium glutamicum. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2015; 1858:130-8. [PMID: 26494188 DOI: 10.1016/j.bbamem.2015.10.010] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/19/2015] [Revised: 10/14/2015] [Accepted: 10/17/2015] [Indexed: 11/20/2022]
Abstract
The mechanosensitive (MS) channel MscCG from the soil bacterium Corynebacterium glutamicum functions as a major glutamate exporter. MscCG belongs to a subfamily of the bacterial MscS-like channels, which play an important role in osmoregulation. To understand the structural and functional features of MscCG, we investigated the role of the carboxyl-terminal domain, whose relevance for the channel gating has been unknown. The chimeric channel MscS-(C-MscCG), which is a fusion protein between the carboxyl terminal domain of MscCG and the MscS channel, was examined by the patch clamp technique. We found that the chimeric channel exhibited MS channel activity in Escherichia coli spheroplasts characterized by a lower activation threshold and slow closing compared to MscS. The chimeric channel MscS-(C-MscCG) was successfully reconstituted into azolectin liposomes and exhibited gating hysteresis in a voltage-dependent manner, especially at high pipette voltages. Moreover, the channel remained open after releasing pipette pressure at membrane potentials physiologically relevant for C. glutamicum. This contribution to the gating hysteresis of the C-terminal domain of MscCG confers to the channel gating properties highly suitable for release of intracellular solutes.
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17
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Yano K, Wachi M, Tsuchida S, Kitazume T, Iwai N. Degradation of benzotrifluoride via the dioxygenase pathway in Rhodococcus sp. 065240. Biosci Biotechnol Biochem 2015; 79:496-504. [DOI: 10.1080/09168451.2014.982502] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
Abstract
We previously isolated Rhodococcus sp. 065240, which catalyzes the defluorination of benzotrifluoride (BTF). In order to investigate the mechanism of this degradation of BTF, we performed proteomic analysis of cells grown with or without BTF. Three proteins, which resemble dioxygenase pathway enzymes responsible for isopropylbenzene degradation from Rhodococcus erythropolis BD2, were induced by BTF. Genomic PCR and DNA sequence analysis revealed that the Rhodococcus sp. 065240 carries the gene cluster, btf, which is highly homologous to the ipb gene cluster from R. erythropolis BD2. A mutant strain, which could not catalyze BTF defluorination, was isolated from 065240 strain by UV mutagenesis. The mutant strain had one mutation in the btfT gene, which encodes a response regulator of the two component system. The defluorinating ability of the mutant strain was recovered by complementation of btfT. These results suggest that the btf gene cluster is responsible for degradation of BTF.
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Affiliation(s)
- Kenichi Yano
- Department of Bioengineering, Tokyo Institute of Technology, Yokohama, Japan
| | - Masaaki Wachi
- Department of Bioengineering, Tokyo Institute of Technology, Yokohama, Japan
| | - Sakiko Tsuchida
- Department of Bioengineering, Tokyo Institute of Technology, Yokohama, Japan
| | - Tomoya Kitazume
- Department of Bioengineering, Tokyo Institute of Technology, Yokohama, Japan
| | - Noritaka Iwai
- Department of Bioengineering, Tokyo Institute of Technology, Yokohama, Japan
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18
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Kim SJ, Hyeon JE, Jeon SD, Choi GW, Han SO. Bi-functional cellulases complexes displayed on the cell surface of Corynebacterium glutamicum increase hydrolysis of lignocelluloses at elevated temperature. Enzyme Microb Technol 2014; 66:67-73. [PMID: 25248702 DOI: 10.1016/j.enzmictec.2014.08.010] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2014] [Revised: 08/20/2014] [Accepted: 08/22/2014] [Indexed: 12/11/2022]
Abstract
Introducing cellulases into Corynebacterium glutamicum leads to the direct degradation of lignocellulosic materials for energy sources. In this study, a cellulase complex containing two cellulolytic enzymes, endoglucanase E (CelE) and β-glucosidase A (BglA), was established to completely degrade cellulose to glucose. The cellulases complexes were displayed on the cell surface of C. glutamicum by using the mechanosensitive channel (Msc) to anchor enzymes in the cytoplasmic membrane. As confirmed by comparison enzyme activities in the cell pellet fraction and supernatant and dual color based immunofluorescence microscopy, the cellulolytic enzymes was successfully associated with the cell surface of C. glutamicum. The displayed cellulases complexes had a synergic effect on the direct conversion of biomass to reducing sugars leading to 3.1- to 6.0-fold increase compared to the conversion by the secreted cellulases complexes. In addition, the displayed cellulases complexes increased the residual activities of cCelE and cBglA at 70°C from 28.3% and 24.3% in the secreted form to 65.1% and 82.8%, respectively. The display of cellulases complexes on the cell surface of C. glutamicum enhances the polysaccharide equivalent and the direct saccharification of low cost biomass via the action of multi-thermostable enzyme complexes.
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Affiliation(s)
- Su Jung Kim
- Department of Biotechnology, Korea University, Seoul 136-701, Republic of Korea
| | - Jeong Eun Hyeon
- Department of Biotechnology, Korea University, Seoul 136-701, Republic of Korea
| | - Sang Duck Jeon
- Department of Biotechnology, Korea University, Seoul 136-701, Republic of Korea
| | - Gi-wook Choi
- Changhae Advanced Institute of Technology, Changhae Ethanol C., Ltd., Jeonju 561-203, Republic of Korea
| | - Sung Ok Han
- Department of Biotechnology, Korea University, Seoul 136-701, Republic of Korea.
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19
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Schüürmann J, Quehl P, Festel G, Jose J. Bacterial whole-cell biocatalysts by surface display of enzymes: toward industrial application. Appl Microbiol Biotechnol 2014; 98:8031-46. [DOI: 10.1007/s00253-014-5897-y] [Citation(s) in RCA: 101] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2014] [Revised: 06/10/2014] [Accepted: 06/11/2014] [Indexed: 11/24/2022]
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20
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The evolutionary 'tinkering' of MscS-like channels: generation of structural and functional diversity. Pflugers Arch 2014; 467:3-13. [PMID: 24819593 DOI: 10.1007/s00424-014-1522-2] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2014] [Revised: 04/12/2014] [Accepted: 04/15/2014] [Indexed: 12/31/2022]
Abstract
The mechanosensitive channel of small conductance (MscS)-like channel superfamily is present in cell-walled organisms throughout all domains of life (Bacteria, Archaea and Eukarya). In bacteria, members of this channel family play an integral role in the protection of cells against acute downward shifts in environmental osmolarity. In this review, we discuss how evolutionary 'tinkering' has taken MscS-like channels from their currently accepted physiological function in bacterial osmoregulation to potential roles in processes as diverse as amino acid efflux, Ca(2+) regulation and cell division. We also illustrate how this structurally and functionally diverse family of channels represents an essential industrial component in the production of monosodium glutamate, an attractive antibiotic target and a rich source of membrane proteins for the studies of molecular evolution.
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21
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Cox CD, Wann KT, Martinac B. Selectivity mechanisms in MscS-like channels: From structure to function. Channels (Austin) 2013; 8:5-12. [PMID: 24262975 DOI: 10.4161/chan.27107] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
The E. coli mechanosensitive (MS) channel of small conductance (EcMscS) is the prototype of a diverse family of channels present in all domains of life. While EcMscS has been extensively studied, recent developments show that MscS may display some characteristics not widely conserved in this protein subfamily. With numerous members now electrophysiologically characterized, this subfamily of channels displays a breadth of ion selectivity with both anion and cation selective members. The selectivity of these channels may be relatively weak in comparison to voltage-gated channels but their selectivity mechanisms represent great novelty. Recent studies have identified unexpected residues important for selectivity in these homologs revealing different selectivity mechanisms than those employed by voltage gated K(+), Na(+), Ca(2+) and Cl(-) channels whose selectivity filters are housed within their transmembrane pores. This commentary looks at what is currently known about MscS subfamily selectivity and begins to unravel the potential physiological relevance of these differences.
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Affiliation(s)
- Charles D Cox
- School of Pharmacy and Pharmaceutical Sciences; Cardiff University; Cardiff, UK; Victor Chang Cardiac Research Institute; Sydney, New South Wales, Australia
| | - Kenneth T Wann
- School of Pharmacy and Pharmaceutical Sciences; Cardiff University; Cardiff, UK
| | - Boris Martinac
- Victor Chang Cardiac Research Institute; Sydney, New South Wales, Australia
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22
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Lanéelle MA, Tropis M, Daffé M. Current knowledge on mycolic acids in Corynebacterium glutamicum and their relevance for biotechnological processes. Appl Microbiol Biotechnol 2013; 97:9923-30. [PMID: 24113823 DOI: 10.1007/s00253-013-5265-3] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2013] [Revised: 09/12/2013] [Accepted: 09/14/2013] [Indexed: 11/29/2022]
Abstract
Corynebacterium glutamicum is the world's largest producer of glutamate and lysine. Industrial glutamate overproduction is induced by empirical processes, such as biotin limitation, supplementation with specific surfactants or addition of sublethal concentration of certain antibiotics to the culture media. Although Gram-positive bacteria, C. glutamicum and related bacterial species and genera contain, in addition to the plasma membrane, an outer permeability membrane similar to that of Gram-negative microorganisms. As the amino acids have to cross both membranes, their integrity, composition and fluidity influence the export process. While the precise mechanism of the export of the amino acids by C. glutamicum is not fully understood, the excretion of amino acids through the inner membrane involved at least a major export system mechanosensitive channel MscS family (MscCG) encoded by NCgl1221. As the various industrial treatments have been shown to affect the lipid content of the bacterial cell, it is strongly believed that defects in the hallmark of the outer membrane, 2-alkyl, 3-hydroxylated long-chain fatty acids (mycolic acids), could be key factors in the glutamate overproduction. This review aims at giving an overview of the current knowledge on mycolic acids structure, biosynthesis and transfer in C. glutamicum and their relevance for amino acid biotechnological production.
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Affiliation(s)
- Marie-Antoinette Lanéelle
- Team « Mycobacterial Cell Envelopes: Structure, Biosynthesis and Roles », Département "Mécanismes Moléculaires des Infections Mycobactériennes", Centre National de la Recherche Scientifique (CNRS), Institut de Pharmacologie et Biologie Structurale (IPBS), UMR 5089, BP 64182, 205, Route de Narbonne, 31077, Toulouse Cedex 04, France
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