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Warneke R, Herzberg C, Weiß M, Schramm T, Hertel D, Link H, Stülke J. DarA-the central processing unit for the integration of osmotic with potassium and amino acid homeostasis in Bacillus subtilis. J Bacteriol 2024; 206:e0019024. [PMID: 38832794 PMCID: PMC11270874 DOI: 10.1128/jb.00190-24] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2024] [Accepted: 05/08/2024] [Indexed: 06/05/2024] Open
Abstract
Cyclic di-adenosine monophosphate (c-di-AMP) is a second messenger involved in diverse metabolic processes including osmolyte uptake, cell wall homeostasis, as well as antibiotic and heat resistance. This study investigates the role of the c-di-AMP receptor protein DarA in the osmotic stress response in Bacillus subtilis. Through a series of experiments, we demonstrate that DarA plays a central role in the cellular response to osmotic fluctuations. Our findings show that DarA becomes essential under extreme potassium limitation as well as upon salt stress, highlighting its significance in mediating osmotic stress adaptation. Suppressor screens with darA mutants reveal compensatory mechanisms involving the accumulation of osmoprotectants, particularly potassium and citrulline. Mutations affecting various metabolic pathways, including the citric acid cycle as well as glutamate and arginine biosynthesis, indicate a complex interplay between the osmotic stress response and metabolic regulation. In addition, the growth defects of the darA mutant during potassium starvation and salt stress in a strain lacking the high-affinity potassium uptake systems KimA and KtrAB can be rescued by increased affinity of the remaining potassium channel KtrCD or by increased expression of ktrD, thus resulting in increased potassium uptake. Finally, the darA mutant can respond to salt stress by the increased expression of MleN , which can export sodium ions.IMPORTANCEEnvironmental bacteria are exposed to rapidly changing osmotic conditions making an effective adaptation to these changes crucial for the survival of the cells. In Gram-positive bacteria, the second messenger cyclic di-AMP plays a key role in this adaptation by controlling (i) the influx of physiologically compatible organic osmolytes and (ii) the biosynthesis of such osmolytes. In several bacteria, cyclic di-adenosine monophosphate (c-di-AMP) can bind to a signal transduction protein, called DarA, in Bacillus subtilis. So far, no function for DarA has been discovered in any organism. We have identified osmotically challenging conditions that make DarA essential and have identified suppressor mutations that help the bacteria to adapt to those conditions. Our results indicate that DarA is a central component in the integration of osmotic stress with the synthesis of compatible amino acid osmolytes and with the homeostasis of potassium, the first response to osmotic stress.
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Affiliation(s)
- Robert Warneke
- Department of General Microbiology, GZMB, Georg-August-Universität Göttingen, Göttingen, Germany
| | - Christina Herzberg
- Department of General Microbiology, GZMB, Georg-August-Universität Göttingen, Göttingen, Germany
| | - Martin Weiß
- Department of General Microbiology, GZMB, Georg-August-Universität Göttingen, Göttingen, Germany
| | - Thorben Schramm
- Interfaculty Institute for Microbiology and Infection Medicine, Eberhard Karls Universität Tübingen, Tübingen, Germany
| | - Dietrich Hertel
- Department of Plant Ecology and Ecosystems Research, Georg-August-Universität Göttingen, Göttingen, Germany
| | - Hannes Link
- Interfaculty Institute for Microbiology and Infection Medicine, Eberhard Karls Universität Tübingen, Tübingen, Germany
| | - Jörg Stülke
- Interfaculty Institute for Microbiology and Infection Medicine, Eberhard Karls Universität Tübingen, Tübingen, Germany
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2
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Meißner J, Königshof M, Wrede K, Warneke R, Mardoukhi MSY, Commichau FM, Stülke J. Control of asparagine homeostasis in Bacillus subtilis: identification of promiscuous amino acid importers and exporters. J Bacteriol 2024; 206:e0042023. [PMID: 38193659 PMCID: PMC10882977 DOI: 10.1128/jb.00420-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2023] [Accepted: 12/08/2023] [Indexed: 01/10/2024] Open
Abstract
The Gram-positive model bacterium B. subtilis is able to import all proteinogenic amino acids from the environment as well as to synthesize them. However, the players involved in the acquisition of asparagine have not yet been identified for this bacterium. In this work, we used d-asparagine as a toxic analog of l-asparagine to identify asparagine transporters. This revealed that d- but not l-asparagine is taken up by the malate/lactate antiporter MleN. Specific strains that are sensitive to the presence of l-asparagine due to the lack of the second messenger cyclic di-AMP or due to the intracellular accumulation of this amino acid were used to isolate and characterize suppressor mutants that were resistant to the presence of otherwise growth-inhibiting concentrations of l-asparagine. These screens identified the broad-spectrum amino acid importers AimA and BcaP as responsible for the acquisition of l-asparagine. The amino acid exporter AzlCD allows detoxification of l-asparagine in addition to 4-azaleucine and histidine. This work supports the idea that amino acids are often transported by promiscuous importers and exporters. However, our work also shows that even stereo-enantiomeric amino acids do not necessarily use the same transport systems.IMPORTANCETransport of amino acid is a poorly studied function in many bacteria, including the model organism Bacillus subtilis. The identification of transporters is hampered by the redundancy of transport systems for most amino acids as well as by the poor specificity of the transporters. Here, we apply several strategies to use the growth-inhibitive effect of many amino acids under defined conditions to isolate suppressor mutants that exhibit either reduced uptake or enhanced export of asparagine, resulting in the identification of uptake and export systems for l-asparagine. The approaches used here may be useful for the identification of transporters for other amino acids both in B. subtilis and in other bacteria.
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Affiliation(s)
- Janek Meißner
- Department of General Microbiology, Institute for Microbiology & Genetics, GZMB, Georg-August-University Göttingen, Göttingen, Germany
| | - Manuel Königshof
- Department of General Microbiology, Institute for Microbiology & Genetics, GZMB, Georg-August-University Göttingen, Göttingen, Germany
| | - Katrin Wrede
- Department of General Microbiology, Institute for Microbiology & Genetics, GZMB, Georg-August-University Göttingen, Göttingen, Germany
| | - Robert Warneke
- Department of General Microbiology, Institute for Microbiology & Genetics, GZMB, Georg-August-University Göttingen, Göttingen, Germany
| | | | - Fabian M. Commichau
- FG Molecular Microbiology, Institute for Biology, University of Hohenheim, Stuttgart, Germany
| | - Jörg Stülke
- Department of General Microbiology, Institute for Microbiology & Genetics, GZMB, Georg-August-University Göttingen, Göttingen, Germany
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3
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Prokaryotic Na+/H+ Exchangers—Transport Mechanism and Essential Residues. Int J Mol Sci 2022; 23:ijms23169156. [PMID: 36012428 PMCID: PMC9408914 DOI: 10.3390/ijms23169156] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2022] [Revised: 08/09/2022] [Accepted: 08/13/2022] [Indexed: 11/16/2022] Open
Abstract
Na+/H+ exchangers are essential for Na+ and pH homeostasis in all organisms. Human Na+/H+ exchangers are of high medical interest, and insights into their structure and function are aided by the investigation of prokaryotic homologues. Most prokaryotic Na+/H+ exchangers belong to either the Cation/Proton Antiporter (CPA) superfamily, the Ion Transport (IT) superfamily, or the Na+-translocating Mrp transporter superfamily. Several structures have been solved so far for CPA and Mrp members, but none for the IT members. NhaA from E. coli has served as the prototype of Na+/H+ exchangers due to the high amount of structural and functional data available. Recent structures from other CPA exchangers, together with diverse functional information, have allowed elucidation of some common working principles shared by Na+/H+ exchangers from different families, such as the type of residues involved in the substrate binding and even a simple mechanism sufficient to explain the pH regulation in the CPA and IT superfamilies. Here, we review several aspects of prokaryotic Na+/H+ exchanger structure and function, discussing the similarities and differences between different transporters, with a focus on the CPA and IT exchangers. We also discuss the proposed transport mechanisms for Na+/H+ exchangers that explain their highly pH-regulated activity profile.
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4
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Bangar SP, Suri S, Trif M, Ozogul F. Organic acids production from lactic acid bacteria: A preservation approach. FOOD BIOSCI 2022. [DOI: 10.1016/j.fbio.2022.101615] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
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5
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Soares-Silva I, Ribas D, Sousa-Silva M, Azevedo-Silva J, Rendulić T, Casal M. Membrane transporters in the bioproduction of organic acids: state of the art and future perspectives for industrial applications. FEMS Microbiol Lett 2021; 367:5873408. [PMID: 32681640 PMCID: PMC7419537 DOI: 10.1093/femsle/fnaa118] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2019] [Accepted: 07/17/2020] [Indexed: 12/16/2022] Open
Abstract
Organic acids such as monocarboxylic acids, dicarboxylic acids or even more complex molecules such as sugar acids, have displayed great applicability in the industry as these compounds are used as platform chemicals for polymer, food, agricultural and pharmaceutical sectors. Chemical synthesis of these compounds from petroleum derivatives is currently their major source of production. However, increasing environmental concerns have prompted the production of organic acids by microorganisms. The current trend is the exploitation of industrial biowastes to sustain microbial cell growth and valorize biomass conversion into organic acids. One of the major bottlenecks for the efficient and cost-effective bioproduction is the export of organic acids through the microbial plasma membrane. Membrane transporter proteins are crucial elements for the optimization of substrate import and final product export. Several transporters have been expressed in organic acid-producing species, resulting in increased final product titers in the extracellular medium and higher productivity levels. In this review, the state of the art of plasma membrane transport of organic acids is presented, along with the implications for industrial biotechnology.
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Affiliation(s)
- I Soares-Silva
- Centre of Molecular and Environmental Biology (CBMA), Department of Biology, University of Minho, Campus de Gualtar, Braga 4710-057, Portugal.,Institute of Science and Innovation for Bio-Sustainability (IB-S), University of Minho, Campus de Gualtar, Braga 4710-057, Portugal
| | - D Ribas
- Centre of Molecular and Environmental Biology (CBMA), Department of Biology, University of Minho, Campus de Gualtar, Braga 4710-057, Portugal.,Institute of Science and Innovation for Bio-Sustainability (IB-S), University of Minho, Campus de Gualtar, Braga 4710-057, Portugal
| | - M Sousa-Silva
- Centre of Molecular and Environmental Biology (CBMA), Department of Biology, University of Minho, Campus de Gualtar, Braga 4710-057, Portugal.,Institute of Science and Innovation for Bio-Sustainability (IB-S), University of Minho, Campus de Gualtar, Braga 4710-057, Portugal
| | - J Azevedo-Silva
- Centre of Molecular and Environmental Biology (CBMA), Department of Biology, University of Minho, Campus de Gualtar, Braga 4710-057, Portugal.,Institute of Science and Innovation for Bio-Sustainability (IB-S), University of Minho, Campus de Gualtar, Braga 4710-057, Portugal
| | - T Rendulić
- Centre of Molecular and Environmental Biology (CBMA), Department of Biology, University of Minho, Campus de Gualtar, Braga 4710-057, Portugal.,Institute of Science and Innovation for Bio-Sustainability (IB-S), University of Minho, Campus de Gualtar, Braga 4710-057, Portugal
| | - M Casal
- Centre of Molecular and Environmental Biology (CBMA), Department of Biology, University of Minho, Campus de Gualtar, Braga 4710-057, Portugal.,Institute of Science and Innovation for Bio-Sustainability (IB-S), University of Minho, Campus de Gualtar, Braga 4710-057, Portugal
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6
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Kuchina A, Brettner LM, Paleologu L, Roco CM, Rosenberg AB, Carignano A, Kibler R, Hirano M, DePaolo RW, Seelig G. Microbial single-cell RNA sequencing by split-pool barcoding. Science 2020; 371:science.aba5257. [PMID: 33335020 DOI: 10.1126/science.aba5257] [Citation(s) in RCA: 125] [Impact Index Per Article: 31.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2019] [Accepted: 12/08/2020] [Indexed: 12/16/2022]
Abstract
Single-cell RNA sequencing (scRNA-seq) has become an essential tool for characterizing gene expression in eukaryotes, but current methods are incompatible with bacteria. Here, we introduce microSPLiT (microbial split-pool ligation transcriptomics), a high-throughput scRNA-seq method for Gram-negative and Gram-positive bacteria that can resolve heterogeneous transcriptional states. We applied microSPLiT to >25,000 Bacillus subtilis cells sampled at different growth stages, creating an atlas of changes in metabolism and lifestyle. We retrieved detailed gene expression profiles associated with known, but rare, states such as competence and prophage induction and also identified unexpected gene expression states, including the heterogeneous activation of a niche metabolic pathway in a subpopulation of cells. MicroSPLiT paves the way to high-throughput analysis of gene expression in bacterial communities that are otherwise not amenable to single-cell analysis, such as natural microbiota.
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Affiliation(s)
- Anna Kuchina
- Department of Electrical and Computer Engineering, University of Washington, Seattle, WA, USA
| | - Leandra M Brettner
- Department of Bioengineering, University of Washington, Seattle, WA, USA.,Center for Microbiome Sciences and Therapeutics, School of Medicine, University of Washington, Seattle, WA, USA
| | - Luana Paleologu
- Department of Microbiology, University of Washington, Seattle, WA, USA.,Department of Biology, University of Washington, Seattle, WA, USA
| | - Charles M Roco
- Department of Bioengineering, University of Washington, Seattle, WA, USA
| | - Alexander B Rosenberg
- Department of Electrical and Computer Engineering, University of Washington, Seattle, WA, USA
| | - Alberto Carignano
- Department of Electrical and Computer Engineering, University of Washington, Seattle, WA, USA
| | - Ryan Kibler
- Biological Physics, Structure, and Design, University of Washington, Seattle, WA, USA
| | - Matthew Hirano
- Department of Electrical and Computer Engineering, University of Washington, Seattle, WA, USA
| | - R William DePaolo
- Center for Microbiome Sciences and Therapeutics, School of Medicine, University of Washington, Seattle, WA, USA.,Department of Medicine, Division of Gastroenterology, School of Medicine, University of Washington, Seattle, WA, USA
| | - Georg Seelig
- Department of Electrical and Computer Engineering, University of Washington, Seattle, WA, USA. .,Molecular Engineering and Sciences Institute, University of Washington, Seattle, WA, USA.,Paul G. Allen School of Computer Science and Engineering, University of Washington, Seattle, WA, USA
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7
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Wang L, Zou Q, Yan M, Wang Y, Guo S, Zhang R, Song Y, Li X, Chen H, Shao L, Meng L, Jiang J. Polar or Charged Residues Located in Four Highly Conserved Motifs Play a Vital Role in the Function or pH Response of a UPF0118 Family Na +(Li +)/H + Antiporter. Front Microbiol 2020; 11:841. [PMID: 32457721 PMCID: PMC7221264 DOI: 10.3389/fmicb.2020.00841] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2020] [Accepted: 04/08/2020] [Indexed: 01/15/2023] Open
Abstract
Functionally uncharacterized UPF0118 family has been re-designated as autoinducer-2 exporter (AI-2E) family since one of its members, Escherichia coli YdgG, was identified to function as an AI-2E. However, it's very likely that AI-2E family members may exhibit significantly distinct functions due to low identities between them. Recently, we identified one member of this family designated as UPF0118 to represent a novel class of Na+(Li+)/H+ antiporters. In this study, we presented that UPF0118, together with its homologs, should represent an independent group of AI-2E family, designated as Na+/H+ Antiporter Group. Notably, this group shows five highly conserved motifs designated as Motifs A to E, which are not detected in the majority of AI-2E family members. Functional analysis established that polar or charged residues located in Motif A to D play a vital role in Na+(Li+)/H+ antiport activity or pH response of UPF0118. However, three basic residues located in Motif E are not involved in the function of UPF0118, although the truncation of C terminus resulted in the non-expression of this transporter. Therefore, we propose that E179-R182-K215-Q217-D251-R292-R293-E296-K298-S30 7 located in Motifs A to D can be used for signature functional motifs to recognize whether AI-2E family members function as Na+(Li+)/H+ antiporters. Current findings positively contribute to the knowledge of molecular mechanism of Na+, Li+ transporting and pH response of UPF0118, and the functional prediction of uncharacterized AI-2E family members.
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Affiliation(s)
- Lidan Wang
- Department of Microbiology and Biotechnology, College of Biological Sciences, Northeast Agricultural University, Harbin, China
| | - Qiao Zou
- Department of Microbiology and Biotechnology, College of Biological Sciences, Northeast Agricultural University, Harbin, China
| | - Mingxue Yan
- Department of Microbiology and Biotechnology, College of Biological Sciences, Northeast Agricultural University, Harbin, China
| | - Yuting Wang
- Department of Microbiology and Biotechnology, College of Biological Sciences, Northeast Agricultural University, Harbin, China
| | - Sijia Guo
- Department of Microbiology and Biotechnology, College of Biological Sciences, Northeast Agricultural University, Harbin, China
| | - Rui Zhang
- Department of Microbiology and Biotechnology, College of Biological Sciences, Northeast Agricultural University, Harbin, China
| | - Yang Song
- Department of Microbiology and Biotechnology, College of Biological Sciences, Northeast Agricultural University, Harbin, China
| | - Xiaofang Li
- Department of Microbiology and Biotechnology, College of Biological Sciences, Northeast Agricultural University, Harbin, China
| | - Huiwen Chen
- Department of Microbiology and Biotechnology, College of Biological Sciences, Northeast Agricultural University, Harbin, China
| | - Li Shao
- Department of Microbiology and Biotechnology, College of Biological Sciences, Northeast Agricultural University, Harbin, China
| | - Lin Meng
- Department of Microbiology and Biotechnology, College of Biological Sciences, Northeast Agricultural University, Harbin, China
| | - Juquan Jiang
- Department of Microbiology and Biotechnology, College of Biological Sciences, Northeast Agricultural University, Harbin, China
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8
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Abdel-Motaal H, Meng L, Zhang Z, Abdelazez AH, Shao L, Xu T, Meng F, Abozaed S, Zhang R, Jiang J. An Uncharacterized Major Facilitator Superfamily Transporter From Planococcus maritimus Exhibits Dual Functions as a Na +(Li +, K +)/H + Antiporter and a Multidrug Efflux Pump. Front Microbiol 2018; 9:1601. [PMID: 30061877 PMCID: PMC6055358 DOI: 10.3389/fmicb.2018.01601] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2018] [Accepted: 06/27/2018] [Indexed: 02/01/2023] Open
Abstract
Within major facilitator superfamily (MFS), up to 27 unknown major facilitator families and many members of 60 well-characterized families have been functionally unknown as yet, due to their sharing no or significantly low sequence identity with characterized MFS members. Here we present the first report on the characterization of one functionally unknown MFS transporter designated MdrP with the accession version No. ANU18183.1 from the slight halophile Planococcus maritimus DS 17275T. During the screening of Na+/H+ antiporter genes, we found at first that MdrP exhibits Na+(Li+, K+)/H+ antiport activity, and propose that it should represent a novel class of Na+(Li+, K+)/H+ antiporters. However, we speculate that MdrP may possess an additional protein function. The existence of the signature Motif A of drug/H+antiporter (DHA) family members and phylogenetic analysis suggest that MdrP may also function as a drug efflux pump, which was established by minimum inhibitory concentration tests and drug efflux activity assays. Taken together, this novel MFS transporter exhibits dual functions as a Na+(Li+, K+)/H+ antiporter and a multidrug efflux pump, which will be very helpful to not only positively contribute to the function prediction of uncharacterized MFS members especially DHA1 family ones, but also broaden the knowledge of Na+/H+ antiporters.
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Affiliation(s)
- Heba Abdel-Motaal
- Key Laboratory of Agricultural Microbiology of Heilongjiang Province, and Department of Microbiology and Biotechnology, College of Life Sciences, Northeast Agricultural University, Harbin, China.,Department of Microbiology, Agriculture Research Center, Soils, Water, Environment and Microbiology Research Institute, Giza, Egypt
| | - Lin Meng
- Key Laboratory of Agricultural Microbiology of Heilongjiang Province, and Department of Microbiology and Biotechnology, College of Life Sciences, Northeast Agricultural University, Harbin, China
| | - Zhenglai Zhang
- Key Laboratory of Agricultural Microbiology of Heilongjiang Province, and Department of Microbiology and Biotechnology, College of Life Sciences, Northeast Agricultural University, Harbin, China
| | - Amro H Abdelazez
- Key Laboratory of Agricultural Microbiology of Heilongjiang Province, and Department of Microbiology and Biotechnology, College of Life Sciences, Northeast Agricultural University, Harbin, China
| | - Li Shao
- Key Laboratory of Agricultural Microbiology of Heilongjiang Province, and Department of Microbiology and Biotechnology, College of Life Sciences, Northeast Agricultural University, Harbin, China
| | - Tong Xu
- Key Laboratory of Agricultural Microbiology of Heilongjiang Province, and Department of Microbiology and Biotechnology, College of Life Sciences, Northeast Agricultural University, Harbin, China
| | - Fankui Meng
- Key Laboratory of Agricultural Microbiology of Heilongjiang Province, and Department of Microbiology and Biotechnology, College of Life Sciences, Northeast Agricultural University, Harbin, China
| | - Shaima Abozaed
- Department of Microbiology, Agriculture Research Center, Soils, Water, Environment and Microbiology Research Institute, Giza, Egypt
| | - Rui Zhang
- Key Laboratory of Agricultural Microbiology of Heilongjiang Province, and Department of Microbiology and Biotechnology, College of Life Sciences, Northeast Agricultural University, Harbin, China
| | - Juquan Jiang
- Key Laboratory of Agricultural Microbiology of Heilongjiang Province, and Department of Microbiology and Biotechnology, College of Life Sciences, Northeast Agricultural University, Harbin, China
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9
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Shao L, Abdel-Motaal H, Chen J, Chen H, Xu T, Meng L, Zhang Z, Meng F, Jiang J. Characterization of a Functionally Unknown Arginine-Aspartate-Aspartate Family Protein From Halobacillus andaensis and Functional Analysis of Its Conserved Arginine/Aspartate Residues. Front Microbiol 2018; 9:807. [PMID: 29922240 PMCID: PMC5996927 DOI: 10.3389/fmicb.2018.00807] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2018] [Accepted: 04/10/2018] [Indexed: 01/15/2023] Open
Abstract
Arginine–aspartate–aspartate (RDD) family, representing a category of transmembrane proteins containing one highly conserved arginine and two highly conserved aspartates, has been functionally uncharacterized as yet. Here we present the characterization of a member of this family designated RDD from the moderate halophile Halobacillus andaensis NEAU-ST10-40T and report for the first time that RDD should function as a novel Na+(Li+, K+)/H+ antiporter. It’s more interesting whether the highly conserved arginine/aspartate residues among the whole family or between RDD and its selected homologs are related to the protein function. Therefore, we analyzed their roles in the cation-transporting activity through site-directed mutagenesis and found that D154, R124, R129, and D158 are indispensable for Na+(Li+, K+)/H+ antiport activity whereas neither R35 nor D42 is involved in Na+(Li+, K+)/H+ antiport activity. As a dual representative of Na+(Li+, K+)/H+ antiporters and RDD family proteins, the characterization of RDD and the analysis of its important residues will positively contribute to the knowledge of the cation-transporting mechanisms of this novel antiporter and the roles of highly conserved arginine/aspartate residues in the functions of RDD family proteins.
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Affiliation(s)
- Li Shao
- Department of Microbiology and Biotechnology, College of Life Sciences, Northeast Agricultural University, Harbin, China
| | - Heba Abdel-Motaal
- Department of Microbiology and Biotechnology, College of Life Sciences, Northeast Agricultural University, Harbin, China
| | - Jin Chen
- Department of Microbiology and Biotechnology, College of Life Sciences, Northeast Agricultural University, Harbin, China
| | - Huiwen Chen
- Department of Microbiology and Biotechnology, College of Life Sciences, Northeast Agricultural University, Harbin, China
| | - Tong Xu
- Department of Microbiology and Biotechnology, College of Life Sciences, Northeast Agricultural University, Harbin, China
| | - Lin Meng
- Department of Microbiology and Biotechnology, College of Life Sciences, Northeast Agricultural University, Harbin, China
| | - Zhenglai Zhang
- Department of Microbiology and Biotechnology, College of Life Sciences, Northeast Agricultural University, Harbin, China
| | - Fankui Meng
- Department of Microbiology and Biotechnology, College of Life Sciences, Northeast Agricultural University, Harbin, China
| | - Juquan Jiang
- Department of Microbiology and Biotechnology, College of Life Sciences, Northeast Agricultural University, Harbin, China
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10
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In Vivo-Selected Compensatory Mutations Restore the Fitness Cost of Mosaic penA Alleles That Confer Ceftriaxone Resistance in Neisseria gonorrhoeae. mBio 2018; 9:mBio.01905-17. [PMID: 29615507 PMCID: PMC5885032 DOI: 10.1128/mbio.01905-17] [Citation(s) in RCA: 41] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
Resistance to ceftriaxone in Neisseria gonorrhoeae is mainly conferred by mosaic penA alleles that encode penicillin-binding protein 2 (PBP2) variants with markedly lower rates of acylation by ceftriaxone. To assess the impact of these mosaic penA alleles on gonococcal fitness, we introduced the mosaic penA alleles from two ceftriaxone-resistant (Cror) clinical isolates (H041 and F89) into a Cros strain (FA19) by allelic exchange and showed that the resultant Cror mutants were significantly outcompeted by the Cros parent strain in vitro and in a murine infection model. Four Cror compensatory mutants of FA19 penA41 were isolated independently from mice that outcompeted the parent strain both in vitro and in vivo. One of these compensatory mutants (LV41C) displayed a unique growth profile, with rapid log growth followed by a sharp plateau/gradual decline at stationary phase. Genome sequencing of LV41C revealed a mutation (G348D) in the acnB gene encoding the bifunctional aconitate hydratase 2/2 methylisocitrate dehydratase. Introduction of the acnBG348D allele into FA19 penA41 conferred both a growth profile that phenocopied that of LV41C and a fitness advantage, although not as strongly as that exhibited by the original compensatory mutant, suggesting the existence of additional compensatory mutations. The mutant aconitase appears to be a functional knockout with lower activity and expression than wild-type aconitase. Transcriptome sequencing (RNA-seq) analysis of FA19 penA41 acnBG348D revealed a large set of upregulated genes involved in carbon and energy metabolism. We conclude that compensatory mutations can be selected in Cror gonococcal strains that increase metabolism to ameliorate their fitness deficit. The emergence of ceftriaxone-resistant (Cror) Neisseria gonorrhoeae has led to the looming threat of untreatable gonorrhea. Whether Cro resistance is likely to spread can be predicted from studies that compare the relative fitnesses of susceptible and resistant strains that differ only in the penA gene that confers Cro resistance. We showed that mosaic penA alleles found in Cror clinical isolates are outcompeted by the Cros parent strain in vitro and in vivo but that compensatory mutations that allow ceftriaxone resistance to be maintained by increasing bacterial fitness are selected during mouse infection. One compensatory mutant that was studied in more detail had a mutation in acnB, which encodes the aconitase that functions in the tricarboxylic acid (TCA) cycle. This study illustrates that compensatory mutations can be selected during infection, which we hypothesize may allow the spread of Cro resistance in nature. This study also provides novel insights into gonococcal metabolism and physiology.
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11
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Transcriptomic profiles of Clostridium ljungdahlii during lithotrophic growth with syngas or H 2 and CO 2 compared to organotrophic growth with fructose. Sci Rep 2017; 7:13135. [PMID: 29030620 PMCID: PMC5640608 DOI: 10.1038/s41598-017-12712-w] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2017] [Accepted: 09/14/2017] [Indexed: 01/13/2023] Open
Abstract
Clostridium ljungdahlii derives energy by lithotrophic and organotrophic acetogenesis. C. ljungdahlii was grown organotrophically with fructose and also lithotrophically, either with syngas - a gas mixture containing hydrogen (H2), carbon dioxide (CO2), and carbon monoxide (CO), or with H2 and CO2. Gene expression was compared quantitatively by microarrays using RNA extracted from all three conditions. Gene expression with fructose and with H2/CO2 was compared by RNA-Seq. Upregulated genes with both syngas and H2/CO2 (compared to fructose) point to the urea cycle, uptake and degradation of peptides and amino acids, response to sulfur starvation, potentially NADPH-producing pathways involving (S)-malate and ornithine, quorum sensing, sporulation, and cell wall remodeling, suggesting a global and multicellular response to lithotrophic conditions. With syngas, the upregulated (R)-lactate dehydrogenase gene represents a route of electron transfer from ferredoxin to NAD. With H2/CO2, flavodoxin and histidine biosynthesis genes were upregulated. Downregulated genes corresponded to an intracytoplasmic microcompartment for disposal of methylglyoxal, a toxic byproduct of glycolysis, as 1-propanol. Several cytoplasmic and membrane-associated redox-active protein genes were differentially regulated. The transcriptomic profiles of C. ljungdahlii in lithotrophic and organotrophic growth modes indicate large-scale physiological and metabolic differences, observations that may guide biofuel and commodity chemical production with this species.
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Wang Y, Song N, Yang L, Abdel-motaal H, Zhang R, Zhang Z, Meng F, Jiang J. A novel NhaD-type Na+/H+ antiporter from the moderate halophile and alkaliphile Halomonas alkaliphila. Can J Microbiol 2017; 63:596-607. [DOI: 10.1139/cjm-2017-0104] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
In this study, a NhaD-type Na+/H+ antiporter gene designated Ha-nhaD was obtained by selection of genomic DNA from the moderate halophile and alkaliphile Halomonas alkaliphila in Escherichia coli KNabc lacking 3 major Na+/H+ antiporters. The presence of Ha-NhaD conferred tolerance of E. coli KNabc to NaCl up to 0.6 mol·L–1 and to LiCl up to 0.2 mol·L–1 and to an alkaline pH. pH-dependent Na+(Li+)/H+ antiport activity was detected from everted membrane vesicles prepared from E. coli KNabc/pUC-nhaD but not those of KNabc/pUC18. Ha-NhaD exhibited Na+(Li+)/H+ antiport activity over a wide pH range from 7.0 to 9.5, with the highest activity at pH 9.0. Protein sequence alignment and phylogenetic analysis revealed that Ha-NhaD is significantly different from the 7 known NhaD-type Na+/H+ antiporters, including Dw-NhaD, Dl-NhaD, Vp-NhaD, Vc-NhaD, Aa-NhaD, He-NhaD, and Ha-NhaD1. Although Ha-NhaD showed a closer phylogenetic relationship with Ha-NhaD2, a significant difference in pH-dependent activity profile exists between Ha-NhaD and Ha-NhaD2. Taken together, Ha-nhaD encodes a novel pH-dependent NhaD-type Na+/H+ antiporter.
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Affiliation(s)
- Yanhong Wang
- Department of Microbiology and Biotechnology, College of Life Sciences, Northeast Agricultural University, Harbin, 150030, People’s Republic of China
- College of Life Science and Technology, Heilongjiang Bayi Agricultural University, Daqing, 163319, People’s Republic of China
| | - Na Song
- Department of Microbiology and Biotechnology, College of Life Sciences, Northeast Agricultural University, Harbin, 150030, People’s Republic of China
| | - Lina Yang
- Department of Microbiology and Biotechnology, College of Life Sciences, Northeast Agricultural University, Harbin, 150030, People’s Republic of China
| | - Heba Abdel-motaal
- Department of Microbiology and Biotechnology, College of Life Sciences, Northeast Agricultural University, Harbin, 150030, People’s Republic of China
- Department of Microbiology, Soils, Water & Environment Research Institute, Agriculture Research Center, Egypt
| | - Rui Zhang
- Department of Microbiology and Biotechnology, College of Life Sciences, Northeast Agricultural University, Harbin, 150030, People’s Republic of China
| | - Zhenglai Zhang
- Department of Microbiology and Biotechnology, College of Life Sciences, Northeast Agricultural University, Harbin, 150030, People’s Republic of China
| | - Fankui Meng
- Department of Microbiology and Biotechnology, College of Life Sciences, Northeast Agricultural University, Harbin, 150030, People’s Republic of China
| | - Juquan Jiang
- Department of Microbiology and Biotechnology, College of Life Sciences, Northeast Agricultural University, Harbin, 150030, People’s Republic of China
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13
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Characterization of a novel two-component Na +(Li +, K +)/H + antiporter from Halomonas zhaodongensis. Sci Rep 2017; 7:4221. [PMID: 28652569 PMCID: PMC5484666 DOI: 10.1038/s41598-017-04236-0] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2017] [Accepted: 05/30/2017] [Indexed: 02/01/2023] Open
Abstract
In this study, genomic DNA was screened for novel Na+/H+ antiporter genes from Halomonas zhaodongensis by selection in Escherichia coli KNabc lacking three major Na+/H+ antiporters. Co-expression of two genes designated umpAB, encoding paired homologous unknown membrane proteins belonging to DUF1538 (domain of unknown function with No. 1538) family, were found to confer E. coli KNabc the tolerance to 0.4 M NaCl and 30 mM LiCl, and an alkaline pH resistance at 8.0. Western blot and co-immunoprecipitation establish that UmpAB localize as a hetero-dimer in the cytoplasmic membranes. Functional analysis reveals that UmpAB exhibit pH-dependent Na+(Li+, K+)/H+ antiport activity at a wide pH range of 6.5 to 9.5 with an optimal pH at 9.0. Neither UmpA nor UmpB showed homology with known single-gene or multi-gene Na+/H+ antiporters, or such proteins as ChaA, MdfA, TetA(L), Nap and PsmrAB with Na+/H+ antiport activity. Phylogenetic analysis confirms that UmpAB should belong to DUF1538 family, which are significantly distant with the above-mentioned proteins with Na+/H+ antiport activity. Taken together, we propose that UmpAB represent a novel two-component Na+(Li+, K+)/H+ antiporter. To the best of our knowledge, this is the first report on the functional analysis of unknown membrane proteins belonging to DUF1538 family.
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14
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Durand S, Braun F, Helfer AC, Romby P, Condon C. sRNA-mediated activation of gene expression by inhibition of 5'-3' exonucleolytic mRNA degradation. eLife 2017; 6. [PMID: 28436820 PMCID: PMC5419742 DOI: 10.7554/elife.23602] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2016] [Accepted: 04/23/2017] [Indexed: 12/13/2022] Open
Abstract
Post-transcriptional control by small regulatory RNA (sRNA) is critical for rapid adaptive processes. sRNAs can directly modulate mRNA degradation in Proteobacteria without interfering with translation. However, Firmicutes have a fundamentally different set of ribonucleases for mRNA degradation and whether sRNAs can regulate the activity of these enzymes is an open question. We show that Bacillus subtilis RoxS, a major trans-acting sRNA shared with Staphylococus aureus, prevents degradation of the yflS mRNA, encoding a malate transporter. In the presence of malate, RoxS transiently escapes from repression by the NADH-sensitive transcription factor Rex and binds to the extreme 5'-end of yflS mRNA. This impairs the 5'-3' exoribonuclease activity of RNase J1, increasing the half-life of the primary transcript and concomitantly enhancing ribosome binding to increase expression of the transporter. Globally, the different targets regulated by RoxS suggest that it helps readjust the cellular NAD+/NADH balance when perturbed by different stimuli.
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Affiliation(s)
- Sylvain Durand
- UMR8261 CNRS, Université Paris Diderot (Sorbonne Paris Cité), Institut de Biologie Physico-Chimique, Paris, France
| | - Frédérique Braun
- UMR8261 CNRS, Université Paris Diderot (Sorbonne Paris Cité), Institut de Biologie Physico-Chimique, Paris, France
| | - Anne-Catherine Helfer
- Université de Strasbourg, CNRS, Architecture et Réactivité de l'ARN, Strasbourg, France
| | - Pascale Romby
- UMR8261 CNRS, Université Paris Diderot (Sorbonne Paris Cité), Institut de Biologie Physico-Chimique, Paris, France.,Université de Strasbourg, CNRS, Architecture et Réactivité de l'ARN, Strasbourg, France
| | - Ciarán Condon
- UMR8261 CNRS, Université Paris Diderot (Sorbonne Paris Cité), Institut de Biologie Physico-Chimique, Paris, France
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15
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Dong P, Wang L, Song N, Yang L, Chen J, Yan M, Chen H, Zhang R, Li J, Abdel-Motaal H, Jiang J. A UPF0118 family protein with uncharacterized function from the moderate halophile Halobacillus andaensis represents a novel class of Na +(Li +)/H + antiporter. Sci Rep 2017; 7:45936. [PMID: 28374790 PMCID: PMC5379678 DOI: 10.1038/srep45936] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2017] [Accepted: 03/07/2017] [Indexed: 02/06/2023] Open
Abstract
In this study, genomic DNA was screened from Halobacillus andaensis NEAU-ST10-40T by selection in Escherichia coli KNabc lacking three major Na+/H+ antiporters. One gene designated upf0118 exhibiting Na+(Li+)/H+ antiport activity was finally cloned. Protein alignment showed that UPF0118 shares the highest identity of 81.5% with an unannotated gene encoding a protein with uncharacterized protein function belonging to UPF0118 family from H. kuroshimensis, but shares no identity with all known specific Na+(Li+)/H+ antiporter genes or genes with Na+(Li+)/H+ antiport activity. Growth test, western blot and Na+(Li+)/H+ antiport assay revealed that UPF0118 as a transmembrane protein exhibits pH-dependent Na+(Li+)/H+ antiport activity. Phylogenetic analysis indicated that UPF0118 clustered with all its homologs belonging to UPF0118 family at a wide range of 22–82% identities with the bootstrap value of 92%, which was significantly distant with all known specific single-gene Na+(Li+)/H+ antiporters and single-gene proteins with the Na+(Li+)/H+ antiport activity. Taken together, we propose that UPF0118 should represent a novel class of Na+(Li+)/H+ antiporter. To the best of our knowledge, this is the first report on the functional analysis of a protein with uncharacterized protein function as a representative of UPF0118 family containing the domain of unknown function, DUF20.
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Affiliation(s)
- Ping Dong
- Department of Microbiology and Biotechnology, College of Life Sciences, Northeast Agricultural University, Harbin, 150030, PR China
| | - Lidan Wang
- Department of Microbiology and Biotechnology, College of Life Sciences, Northeast Agricultural University, Harbin, 150030, PR China
| | - Na Song
- Department of Microbiology and Biotechnology, College of Life Sciences, Northeast Agricultural University, Harbin, 150030, PR China
| | - Lina Yang
- Department of Microbiology and Biotechnology, College of Life Sciences, Northeast Agricultural University, Harbin, 150030, PR China
| | - Jin Chen
- Department of Microbiology and Biotechnology, College of Life Sciences, Northeast Agricultural University, Harbin, 150030, PR China
| | - Mingxue Yan
- Department of Microbiology and Biotechnology, College of Life Sciences, Northeast Agricultural University, Harbin, 150030, PR China
| | - Huiwen Chen
- Department of Microbiology and Biotechnology, College of Life Sciences, Northeast Agricultural University, Harbin, 150030, PR China
| | - Rui Zhang
- Department of Microbiology and Biotechnology, College of Life Sciences, Northeast Agricultural University, Harbin, 150030, PR China
| | - Jincheng Li
- Department of Microbiology and Biotechnology, College of Life Sciences, Northeast Agricultural University, Harbin, 150030, PR China
| | - Heba Abdel-Motaal
- Department of Microbiology and Biotechnology, College of Life Sciences, Northeast Agricultural University, Harbin, 150030, PR China
| | - Juquan Jiang
- Department of Microbiology and Biotechnology, College of Life Sciences, Northeast Agricultural University, Harbin, 150030, PR China
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On the principle of ion selectivity in Na+/H+-coupled membrane proteins: experimental and theoretical studies of an ATP synthase rotor. Proc Natl Acad Sci U S A 2015; 112:E1057-66. [PMID: 25713346 DOI: 10.1073/pnas.1421202112] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Numerous membrane transporters and enzymes couple their mechanisms to the permeation of Na(+) or H(+), thereby harnessing the energy stored in the form of transmembrane electrochemical potential gradients to sustain their activities. The molecular and environmental factors that control and modulate the ion specificity of most of these systems are, however, poorly understood. Here, we use isothermal titration calorimetry to determine the Na(+)/H(+) selectivity of the ion-driven membrane rotor of an F-type ATP synthase. Consistent with earlier theoretical predictions, we find that this rotor is significantly H(+) selective, although not sufficiently to be functionally coupled to H(+), owing to the large excess of Na(+) in physiological settings. The functional Na(+) specificity of this ATP synthase thus results from two opposing factors, namely its inherent chemical selectivity and the relative availability of the coupling ion. Further theoretical studies of this membrane rotor, and of two others with a much stronger and a slightly weaker H(+) selectivity, indicate that, although the inherent selectivity of their ion-binding sites is largely set by the balance of polar and hydrophobic groups flanking a conserved carboxylic side chain, subtle variations in their structure and conformational dynamics, for a similar chemical makeup, can also have a significant contribution. We propose that the principle of ion selectivity outlined here may provide a rationale for the differentiation of Na(+)- and H(+)-coupled systems in other families of membrane transporters and enzymes.
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17
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Sorokin DY, Berben T, Melton ED, Overmars L, Vavourakis CD, Muyzer G. Microbial diversity and biogeochemical cycling in soda lakes. Extremophiles 2014; 18:791-809. [PMID: 25156418 PMCID: PMC4158274 DOI: 10.1007/s00792-014-0670-9] [Citation(s) in RCA: 143] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2014] [Accepted: 06/26/2014] [Indexed: 01/26/2023]
Abstract
Soda lakes contain high concentrations of sodium carbonates resulting in a stable elevated pH, which provide a unique habitat to a rich diversity of haloalkaliphilic bacteria and archaea. Both cultivation-dependent and -independent methods have aided the identification of key processes and genes in the microbially mediated carbon, nitrogen, and sulfur biogeochemical cycles in soda lakes. In order to survive in this extreme environment, haloalkaliphiles have developed various bioenergetic and structural adaptations to maintain pH homeostasis and intracellular osmotic pressure. The cultivation of a handful of strains has led to the isolation of a number of extremozymes, which allow the cell to perform enzymatic reactions at these extreme conditions. These enzymes potentially contribute to biotechnological applications. In addition, microbial species active in the sulfur cycle can be used for sulfur remediation purposes. Future research should combine both innovative culture methods and state-of-the-art 'meta-omic' techniques to gain a comprehensive understanding of the microbes that flourish in these extreme environments and the processes they mediate. Coupling the biogeochemical C, N, and S cycles and identifying where each process takes place on a spatial and temporal scale could unravel the interspecies relationships and thereby reveal more about the ecosystem dynamics of these enigmatic extreme environments.
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Affiliation(s)
- Dimitry Y. Sorokin
- Winogradsky Institute of Microbiology, RAS, Moscow, Russia
- Department of Biotechnology, Delft University of Technology, Delft, The Netherlands
| | - Tom Berben
- Institute for Biodiversity and Ecosystem Dynamics, University of Amsterdam, Amsterdam, The Netherlands
| | - Emily Denise Melton
- Institute for Biodiversity and Ecosystem Dynamics, University of Amsterdam, Amsterdam, The Netherlands
| | - Lex Overmars
- Institute for Biodiversity and Ecosystem Dynamics, University of Amsterdam, Amsterdam, The Netherlands
| | - Charlotte D. Vavourakis
- Institute for Biodiversity and Ecosystem Dynamics, University of Amsterdam, Amsterdam, The Netherlands
| | - Gerard Muyzer
- Institute for Biodiversity and Ecosystem Dynamics, University of Amsterdam, Amsterdam, The Netherlands
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Meng L, Hong S, Liu H, Huang H, Sun H, Xu T, Jiang J. Cloning and identification of Group 1 mrp operon encoding a novel monovalent cation/proton antiporter system from the moderate halophile Halomonas zhaodongensis. Extremophiles 2014; 18:963-72. [PMID: 24996797 DOI: 10.1007/s00792-014-0666-5] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2014] [Accepted: 06/05/2014] [Indexed: 11/26/2022]
Abstract
The novel species Halomonas zhaodongensis NEAU-ST10-25(T) recently identified by our group is a moderate halophile which can grow at the range of 0-2.5 M NaCl (optimum 0.5 M) and pH 6-12 (optimum pH 9). To explore its halo-alkaline tolerant mechanism, genomic DNA was screened from NEAU-ST10-25(T) in this study for Na(+)(Li(+))/H(+) antiporter genes by selection in Escherichia coli KNabc lacking three major Na(+)(Li(+))/H(+) antiporters. One mrp operon could confer tolerance of E. coli KNabc to 0.8 M NaCl and 100 mM LiCl, and an alkaline pH. This operon was previously mainly designated mrp (also mnh, pha or sha) due to its multiple resistance and pH-related activity. Here, we will also use mrp to designate the homolog from H. zhaodongensis (Hz_mrp). Sequence analysis and protein alignment showed that Hz_mrp should belong to Group 1 mrp operons. Further phylogenetic analysis reveals that Hz_Mrp system should represent a novel sub-class of Group 1 Mrp systems. This was confirmed by a significant difference in pH-dependent activity profile or the specificity and affinity for the transported monovalent cations between Hz_Mrp system and all the known Mrp systems. Therefore, we propose that Hz_Mrp should be categorized as a novel Group 1 Mrp system.
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Affiliation(s)
- Lin Meng
- Department of Microbiology and Biotechnology, College of Life Sciences, Northeast Agricultural University, Harbin, 150030, People's Republic of China
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The presence of conjugative plasmid pLS20 affects global transcription of Its Bacillus subtilis host and confers beneficial stress resistance to cells. Appl Environ Microbiol 2013; 80:1349-58. [PMID: 24334659 DOI: 10.1128/aem.03154-13] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
Conjugation activity of plasmid pLS20 from Bacillus subtilis subsp. natto is induced when cells are diluted into fresh medium and diminishes as cells enter into stationary-phase growth. Transcriptional profiling shows that during mid-exponential growth, more than 5% of the host genes are affected in the presence of the plasmid, in contrast to the minor changes seen in freshly diluted and stationary-phase cells. Changes occurred in many metabolic pathways, although pLS20 does not confer any detectable burden on its host cell, as well as in membrane and cell wall-associated processes, in the large motility operon, and in several other cellular processes. In agreement with these changes, we found considerable alterations in motility and enzyme activity and increased resistance against several different forms of stress in cells containing the plasmid, revealing that the presence of pLS20 has a broad impact on the physiology of its host cell and increases its stress resistance in multiple aspects. Additionally, we found that the lack of chromosomal gene yueB, known to encode a phage receptor protein, which is upregulated in cells containing pLS20, strongly reduced conjugation efficiency, revealing that pLS20 not only increases fitness of its host but also employs host proteins for efficient transfer into a new cell.
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20
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Carvalho AL, Turner DL, Fonseca LL, Solopova A, Catarino T, Kuipers OP, Voit EO, Neves AR, Santos H. Metabolic and transcriptional analysis of acid stress in Lactococcus lactis, with a focus on the kinetics of lactic acid pools. PLoS One 2013; 8:e68470. [PMID: 23844205 PMCID: PMC3700934 DOI: 10.1371/journal.pone.0068470] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2013] [Accepted: 05/29/2013] [Indexed: 01/27/2023] Open
Abstract
The effect of pH on the glucose metabolism of non-growing cells of L. lactis MG1363 was studied by in vivo NMR in the range 4.8 to 6.5. Immediate pH effects on glucose transporters and/or enzyme activities were distinguished from transcriptional/translational effects by using cells grown at the optimal pH of 6.5 or pre-adjusted to low pH by growth at 5.1. In cells grown at pH 5.1, glucose metabolism proceeds at a rate 35% higher than in non-adjusted cells at the same pH. Besides the upregulation of stress-related genes (such as dnaK and groEL), cells adjusted to low pH overexpressed H(+)-ATPase subunits as well as glycolytic genes. At sub-optimal pHs, the total intracellular pool of lactic acid reached approximately 500 mM in cells grown at optimal pH and about 700 mM in cells grown at pH 5.1. These high levels, together with good pH homeostasis (internal pH always above 6), imply intracellular accumulation of the ionized form of lactic acid (lactate anion), and the concomitant export of the equivalent protons. The average number, n, of protons exported with each lactate anion was determined directly from the kinetics of accumulation of intra- and extracellular lactic acid as monitored online by (13)C-NMR. In cells non-adjusted to low pH, n varies between 2 and 1 during glucose consumption, suggesting an inhibitory effect of intracellular lactate on proton export. We confirmed that extracellular lactate did not affect the lactate: proton stoichiometry. In adjusted cells, n was lower and varied less, indicating a different mix of lactic acid exporters less affected by the high level of intracellular lactate. A qualitative model for pH effects and acid stress adaptation is proposed on the basis of these results.
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Affiliation(s)
- Ana Lúcia Carvalho
- Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa, Oeiras, Portugal
| | - David L. Turner
- Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa, Oeiras, Portugal
| | - Luís L. Fonseca
- Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa, Oeiras, Portugal
- Integrative BioSystems Institute and the Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, Georgia, United States of America
| | - Ana Solopova
- Department of Molecular Genetics, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Haren, The Netherlands
| | - Teresa Catarino
- Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa, Oeiras, Portugal
- Departamento de Química, Faculdade de Ciências e Tecnologia, FCT, Universidade Nova de Lisboa, Caparica, Oeiras, Portugal
| | - Oscar P. Kuipers
- Department of Molecular Genetics, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Haren, The Netherlands
| | - Eberhard O. Voit
- Integrative BioSystems Institute and the Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, Georgia, United States of America
| | - Ana Rute Neves
- Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa, Oeiras, Portugal
| | - Helena Santos
- Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa, Oeiras, Portugal
- * E-mail:
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Adaptation in Haloalkaliphiles and Natronophilic Bacteria. CELLULAR ORIGIN, LIFE IN EXTREME HABITATS AND ASTROBIOLOGY 2013. [DOI: 10.1007/978-94-007-6488-0_5] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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22
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Chen Y, Cao S, Chai Y, Clardy J, Kolter R, Guo JH, Losick R. A Bacillus subtilis sensor kinase involved in triggering biofilm formation on the roots of tomato plants. Mol Microbiol 2012; 85:418-30. [PMID: 22716461 PMCID: PMC3518419 DOI: 10.1111/j.1365-2958.2012.08109.x] [Citation(s) in RCA: 141] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
The soil bacterium Bacillus subtilis is widely used in agriculture as a biocontrol agent able to protect plants from a variety of pathogens. Protection is thought to involve the formation of bacterial communities - biofilms - on the roots of the plants. Here we used confocal microscopy to visualize biofilms on the surface of the roots of tomato seedlings and demonstrated that biofilm formation requires genes governing the production of the extracellular matrix that holds cells together. We further show that biofilm formation was dependent on the sensor histidine kinase KinD and in particular on an extracellular CACHE domain implicated in small molecule sensing. Finally, we report that exudates of tomato roots strongly stimulated biofilm formation ex planta and that an abundant small molecule in the exudates, (L) -malic acid, was able to stimulate biofilm formation at high concentrations in a manner that depended on the KinD CACHE domain. We propose that small signalling molecules released by the roots of tomato plants are directly or indirectly recognized by KinD, triggering biofilm formation.
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Affiliation(s)
- Yun Chen
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA 02138
- Department of Plant Pathology, College of Plant Protection, Nanjing Agricultural University, Nanjing 210095, China
| | - Shugeng Cao
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, 02115
| | - Yunrong Chai
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA 02138
| | - Jon Clardy
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, 02115
| | - Roberto Kolter
- Department of Microbiology and Immunology, Harvard Medical School, Boston, 02115
| | - Jian-hua Guo
- Department of Plant Pathology, College of Plant Protection, Nanjing Agricultural University, Nanjing 210095, China
- Key Laboratory of Integrated Management of Crop Diseases and Pests (Nanjing Agricultural University), Ministry of Education, Nanjing 210095, China
- Engineering Center of Bioresource Pesticide in Jiangsu Province, Nanjing 210095, China
| | - Richard Losick
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA 02138
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23
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Membrane topology screen of secondary transport proteins in structural class ST[3] of the MemGen classification. Confirmation and structural diversity. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2011; 1818:72-81. [PMID: 21983116 DOI: 10.1016/j.bbamem.2011.09.021] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/10/2011] [Revised: 09/22/2011] [Accepted: 09/23/2011] [Indexed: 11/22/2022]
Abstract
The MemGen structural classification of membrane proteins groups families of proteins by hydropathy profile alignment. Class ST[3] of the MemGen classification contains 32 families of transporter proteins including the IT superfamily. Transporters from 19 different families in class ST[3] were evaluated by the TopScreen experimental topology screening method to verify the structural classification by MemGen. TopScreen involves the determination of the cellular disposition of three sites in the polypeptide chain of the proteins which allows for discrimination between different topology models. For nearly all transporters at least one of the predicted localizations is different in the models produced by MemGen and predictor TMHMM. Comparison to the experimental data showed that in all cases the prediction by MemGen was correct. It is concluded that the structural model available for transporters of the [st324]ESS and [st326]2HCT families is also valid for the other families in class ST[3]. The core structure of the model consists of two homologous domains, each containing 5 transmembrane segments, which have an opposite orientation in the membrane. A reentrant loop is present in between the 4th and 5th segments in each domain. Nearly all of the identified and experimentally confirmed structural variations involve additions of transmembrane segments at the boundaries of the core model, at the N- and C-termini or in between the two domains. Most remarkable is a domain swap in two subfamilies of the [st312]NHAC family that results in an inverted orientation of the proteins in the membrane.
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Activation of dormant secondary metabolism neotrehalosadiamine synthesis by an RNA polymerase mutation in Bacillus subtilis. Biosci Biotechnol Biochem 2011; 75:618-23. [PMID: 21512256 DOI: 10.1271/bbb.100854] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Microorganisms possess the ability to produce a variety of commercially important secondary metabolites such as antibiotics. Although it becomes harder and harder to discover useful new compounds, microorganisms still have the potential to produce unknown compounds. One of the reasons for the difficulty in finding new compounds is that the expression level of many secondary metabolite genes is insufficient in wild-type strains. Therefore, a new method of activating gene expression might be a powerful tool for the screening of novel compounds and for strain improvement to overproduce useful compounds. We found that the rifampicin-resistant RNA polymerase mutations stimulate the expression of antibiotic synthetic gene clusters in several microorganisms. In the case of the Gram-positive model organism Bacillus subtilis, one of the rifampicin-resistance mutations resulted in the activation of a dormant secondary metabolism, neotrehalosadiamine synthesis. To clarify this activation mechanism, we first identified the neotrehalosadiamine biosynthetic operon and investigated its transcriptional regulation. Here we summarize our findings on the transcriptional regulation of the neotrehalosadiamine biosynthetic operon and discuss a crucial effect of the rifampicin-resistance mutation on the expression of dormant genes.
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Characterization of a novel riboswitch-regulated lysine transporter in Aggregatibacter actinomycetemcomitans. J Bacteriol 2010; 192:6240-50. [PMID: 20889741 DOI: 10.1128/jb.00935-10] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Aggregatibacter actinomycetemcomitans is an opportunistic pathogen that resides primarily in the mammalian oral cavity. In this environment, A. actinomycetemcomitans faces numerous host- and microbe-derived stresses, including intense competition for nutrients and exposure to the host immune system. While it is clear that A. actinomycetemcomitans responds to precise cues that allow it to adapt and proliferate in the presence of these stresses, little is currently known about the regulatory mechanisms that underlie these responses. Many bacteria use noncoding regulatory RNAs (ncRNAs) to rapidly alter gene expression in response to environmental stresses. Although no ncRNAs have been reported in A. actinomycetemcomitans, we propose that they are likely important for colonization and persistence in the oral cavity. Using a bioinformatic and experimental approach, we identified three putative metabolite-sensing riboswitches and nine small regulatory RNAs (sRNAs) in A. actinomycetemcomitans during planktonic and biofilm growth. Molecular characterization of one of the riboswitches revealed that it is a lysine riboswitch and that its target gene, lysT, encodes a novel lysine-specific transporter. Finally, we demonstrated that lysT and the lysT lysine riboswitch are conserved in over 40 bacterial species, including the phylogenetically related pathogen Haemophilus influenzae.
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Intermolecular cross-linking of monomers in Helicobacter pylori Na+/H+ antiporter NhaA at the dimer interface inhibits antiporter activity. Biochem J 2010; 426:99-108. [PMID: 19922410 DOI: 10.1042/bj20091339] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
We have previously shown that HPNhaA (Helicobacter pylori Na+/H+ antiporter) forms an oligomer in a native membrane of Escherichia coli, and conformational changes of oligomer occur between monomers of the oligomer during ion transport. In the present study, we use Blue-native PAGE to show that HPNhaA forms a dimer. Cysteine-scanning mutagenesis of residues 55-61 in a putative beta-sheet region of loop1 and subsequent functional analyses revealed that the Q58C mutation resulted in an intermolecular disulfide bond. G56C, I59C and G60C were found to be cross-linked by bifunctional cross-linkers. Furthermore, the Q58E mutant did not form a dimer, possibly due to electrostatic repulsion between monomers. These results imply that Gln-58 and the flanking sequence in the putative beta-sheet of the monomer are located close to the identical residues in the dimer. The Q58C mutant of NhaA was almost inactive under non-reducing conditions, and activity was restored under reducing conditions. This result showed that cross-linking at the dimer interface reduces transporter activity by interfering with the flexible association between the monomers. A mutant HPNhaA protein with three amino acid substitutions at residues 57-59 did not form a dimer, and yet was active, indicating that the monomer is functional.
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Kleijn RJ, Buescher JM, Le Chat L, Jules M, Aymerich S, Sauer U. Metabolic fluxes during strong carbon catabolite repression by malate in Bacillus subtilis. J Biol Chem 2009; 285:1587-96. [PMID: 19917605 DOI: 10.1074/jbc.m109.061747] [Citation(s) in RCA: 86] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Commonly glucose is considered to be the only preferred substrate in Bacillus subtilis whose presence represses utilization of other alternative substrates. Because recent data indicate that malate might be an exception, we quantify here the carbon source utilization hierarchy. Based on physiology and transcriptional data during co-utilization experiments with eight carbon substrates, we demonstrate that malate is a second preferred carbon source for B. subtilis, which is rapidly co-utilized with glucose and strongly represses the uptake of alternative substrates. From the different hierarchy and degree of catabolite repression exerted by glucose and malate, we conclude that both substrates might act through different molecular mechanisms. To obtain a quantitative and functional network view of how malate is (co)metabolized, we developed a novel approach to metabolic flux analysis that avoids error-prone, intuitive, and ad hoc decisions on (13)C rearrangements. In particular, we developed a rigorous approach for deriving reaction reversibilities by combining in vivo intracellular metabolite concentrations with a thermodynamic feasibility analysis. The thus-obtained analytical model of metabolism was then used for network-wide isotopologue balancing to estimate the intracellular fluxes. These (13)C-flux data revealed an extraordinarily high malate influx that is primarily catabolized via the gluconeogenic reactions and toward overflow metabolism. Furthermore, a considerable NADPH-producing malic enzyme flux is required to supply the biosynthetically required NADPH in the presence of malate. Co-utilization of glucose and malate resulted in a synergistic decrease of the respiratory tricarboxylic acid cycle flux.
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Affiliation(s)
- Roelco J Kleijn
- Institute of Molecular System Biology, ETH Zürich, CH-8093 Zürich, Switzerland
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Slonczewski JL, Fujisawa M, Dopson M, Krulwich TA. Cytoplasmic pH measurement and homeostasis in bacteria and archaea. Adv Microb Physiol 2009; 55:1-79, 317. [PMID: 19573695 DOI: 10.1016/s0065-2911(09)05501-5] [Citation(s) in RCA: 293] [Impact Index Per Article: 19.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Of all the molecular determinants for growth, the hydronium and hydroxide ions are found naturally in the widest concentration range, from acid mine drainage below pH 0 to soda lakes above pH 13. Most bacteria and archaea have mechanisms that maintain their internal, cytoplasmic pH within a narrower range than the pH outside the cell, termed "pH homeostasis." Some mechanisms of pH homeostasis are specific to particular species or groups of microorganisms while some common principles apply across the pH spectrum. The measurement of internal pH of microbes presents challenges, which are addressed by a range of techniques under varying growth conditions. This review compares and contrasts cytoplasmic pH homeostasis in acidophilic, neutralophilic, and alkaliphilic bacteria and archaea under conditions of growth, non-growth survival, and biofilms. We present diverse mechanisms of pH homeostasis including cell buffering, adaptations of membrane structure, active ion transport, and metabolic consumption of acids and bases.
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Identification and characterization of OscR, a transcriptional regulator involved in osmolarity adaptation in Vibrio cholerae. J Bacteriol 2009; 191:4082-96. [PMID: 19329635 DOI: 10.1128/jb.01540-08] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Vibrio cholerae is a facultative human pathogen. In its aquatic habitat and as it passes through the digestive tract, V. cholerae must cope with fluctuations in salinity. We analyzed the genome-wide transcriptional profile of V. cholerae grown at different NaCl concentrations and determined that the expression of compatible solute biosynthesis and transporter genes, virulence genes, and genes involved in adhesion and biofilm formation is differentially regulated. We determined that salinity modulates biofilm formation, and this response was mediated through the transcriptional regulators VpsR and VpsT. Additionally, a transcriptional regulator controlling an osmolarity adaptation response was identified. This regulator, OscR (osmolarity controlled regulator), was found to modulate the transcription of genes involved in biofilm matrix production and motility in a salinity-dependent manner. oscR mutants were less motile and exhibited enhanced biofilm formation only under low-salt conditions.
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Acid and base stress and transcriptomic responses in Bacillus subtilis. Appl Environ Microbiol 2008; 75:981-90. [PMID: 19114526 DOI: 10.1128/aem.01652-08] [Citation(s) in RCA: 101] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Acid and base environmental stress responses were investigated in Bacillus subtilis. B. subtilis AG174 cultures in buffered potassium-modified Luria broth were switched from pH 8.5 to pH 6.0 and recovered growth rapidly, whereas cultures switched from pH 6.0 to pH 8.5 showed a long lag time. Log-phase cultures at pH 6.0 survived 60 to 100% at pH 4.5, whereas cells grown at pH 7.0 survived <15%. Cells grown at pH 9.0 survived 40 to 100% at pH 10, whereas cells grown at pH 7.0 survived <5%. Thus, growth in a moderate acid or base induced adaptation to a more extreme acid or base, respectively. Expression indices from Affymetrix chip hybridization were obtained for 4,095 protein-encoding open reading frames of B. subtilis grown at external pH 6, pH 7, and pH 9. Growth at pH 6 upregulated acetoin production (alsDS), dehydrogenases (adhA, ald, fdhD, and gabD), and decarboxylases (psd and speA). Acid upregulated malate metabolism (maeN), metal export (czcDO and cadA), oxidative stress (catalase katA; OYE family namA), and the SigX extracytoplasmic stress regulon. Growth at pH 9 upregulated arginine catabolism (roc), which generates organic acids, glutamate synthase (gltAB), polyamine acetylation and transport (blt), the K(+)/H(+) antiporter (yhaTU), and cytochrome oxidoreductases (cyd, ctaACE, and qcrC). The SigH, SigL, and SigW regulons were upregulated at high pH. Overall, greater genetic adaptation was seen at pH 9 than at pH 6, which may explain the lag time required for growth shift to high pH. Low external pH favored dehydrogenases and decarboxylases that may consume acids and generate basic amines, whereas high external pH favored catabolism-generating acids.
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Youn JW, Jolkver E, Krämer R, Marin K, Wendisch VF. Identification and characterization of the dicarboxylate uptake system DccT in Corynebacterium glutamicum. J Bacteriol 2008; 190:6458-66. [PMID: 18658264 PMCID: PMC2566012 DOI: 10.1128/jb.00780-08] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2008] [Accepted: 07/21/2008] [Indexed: 11/20/2022] Open
Abstract
Many bacteria can utilize C(4)-carboxylates as carbon and energy sources. However, Corynebacterium glutamicum ATCC 13032 is not able to use tricarboxylic acid cycle intermediates such as succinate, fumarate, and l-malate as sole carbon sources. Upon prolonged incubation, spontaneous mutants which had gained the ability to grow on succinate, fumarate, and l-malate could be isolated. DNA microarray analysis showed higher mRNA levels of cg0277, which subsequently was named dccT, in the mutants than in the wild type, and transcriptional fusion analysis revealed that a point mutation in the promoter region of dccT was responsible for increased expression. The overexpression of dccT was sufficient to enable the C. glutamicum wild type to grow on succinate, fumarate, and l-malate as the sole carbon sources. Biochemical analyses revealed that DccT, which is a member of the divalent anion/Na(+) symporter family, catalyzes the effective uptake of dicarboxylates like succinate, fumarate, L-malate, and likely also oxaloacetate in a sodium-dependent manner.
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Affiliation(s)
- Jung-Won Youn
- Institute of Molecular Microbiology and Biotechnology, Westfalian Wilhelms University Muenster, Corrensstr. 3, D-48149 Muenster, Germany
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Barabote RD, Rendulic S, Schuster SC, Saier MH. Comprehensive analysis of transport proteins encoded within the genome of Bdellovibrio bacteriovorus. Genomics 2007; 90:424-46. [PMID: 17706914 PMCID: PMC3415317 DOI: 10.1016/j.ygeno.2007.06.002] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2006] [Revised: 06/07/2007] [Accepted: 06/08/2007] [Indexed: 10/22/2022]
Abstract
Bdellovibrio bacteriovorus is a bacterial parasite with an unusual lifestyle. It grows and reproduces in the periplasm of a host prey bacterium. The complete genome sequence of B. bacteriovorus has recently been reported. We have reanalyzed the transport proteins encoded within the B. bacteriovorus genome according to the current content of the Transporter Classification Database. A comprehensive analysis is given on the types and numbers of transport systems that B. bacteriovorus has. In this regard, the potential protein secretory capabilities of at least four types of inner-membrane secretion systems and five types of outer-membrane secretion systems are described. Surprisingly, B. bacteriovorus has a disproportionate percentage of cytoplasmic membrane channels and outer-membrane porins. It has far more TonB/ExbBD-type systems and MotAB-type systems for energizing outer-membrane transport and motility than does Escherichia coli. Analysis of probable substrate specificities of its transporters provides clues to its metabolic preferences. Interesting examples of gene fusions and of potentially overlapping genes are also noted. Our analyses provide a comprehensive, detailed appreciation of the transport capabilities of B. bacteriovorus. They should serve as a guide for functional experimental analyses.
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Affiliation(s)
- Ravi D. Barabote
- Division of Biological Sciences, University of California at San Diego, La Jolla, CA 92093-0116
| | - Snjezana Rendulic
- Division of Biological Sciences, University of California at San Diego, La Jolla, CA 92093-0116
| | - Stephan C. Schuster
- Division of Biological Sciences, University of California at San Diego, La Jolla, CA 92093-0116
| | - Milton H. Saier
- Division of Biological Sciences, University of California at San Diego, La Jolla, CA 92093-0116
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Thomaides HB, Davison EJ, Burston L, Johnson H, Brown DR, Hunt AC, Errington J, Czaplewski L. Essential bacterial functions encoded by gene pairs. J Bacteriol 2006; 189:591-602. [PMID: 17114254 PMCID: PMC1797375 DOI: 10.1128/jb.01381-06] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
To address the need for new antibacterials, a number of bacterial genomes have been systematically disrupted to identify essential genes. Such programs have focused on the disruption of single genes and may have missed functions encoded by gene pairs or multiple genes. In this work, we hypothesized that we could predict the identity of pairs of proteins within one organism that have the same function. We identified 135 putative protein pairs in Bacillus subtilis and attempted to disrupt the genes forming these, singly and then in pairs. The single gene disruptions revealed new genes that could not be disrupted individually and other genes required for growth in minimal medium or for sporulation. The pairwise disruptions revealed seven pairs of proteins that are likely to have the same function, as the presence of one protein can compensate for the absence of the other. Six of these pairs are essential for bacterial viability and in four cases show a pattern of species conservation appropriate for potential antibacterial development. This work highlights the importance of combinatorial studies in understanding gene duplication and identifying functional redundancy.
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Affiliation(s)
- Helena B Thomaides
- Prolysis Ltd., Begbroke Science Park, Sandy Lane, Yarnton OX5 1PF, Oxfordshire, UK.
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Wei Y, Deikus G, Powers B, Shelden V, Krulwich TA, Bechhofer DH. Adaptive gene expression in Bacillus subtilis strains deleted for tetL. J Bacteriol 2006; 188:7090-100. [PMID: 17015648 PMCID: PMC1636236 DOI: 10.1128/jb.00885-06] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2006] [Accepted: 07/25/2006] [Indexed: 11/20/2022] Open
Abstract
The growth properties of a new panel of Bacillus subtilis tetL deletion strains and of a derivative set of strains in which tetL is restored to the chromosome support earlier indications that deletion of tetL results in a range of phenotypes that are unrelated to tetracycline resistance. These phenotypes were not reversed by restoration of a tetL gene to its native locus and were hypothesized to result from secondary mutations that arise when multifunctional tetL is deleted. Such genetic changes would temper the alkali sensitivity and Na(+) sensitivity that accompany loss of the monovalent cation/proton activity of TetL. Microarray comparisons of the transcriptomes of wild-type B. subtilis, a tetL deletion strain, and its tetL-restored derivative showed that 37 up-regulated genes and 13 down-regulated genes in the deletion strain did not change back to wild-type expression patterns after tetL was returned to the chromosome. Up-regulation of the citM gene, which encodes a divalent metal ion-coupled citrate transporter, was shown to account for the Co(2+)-sensitive phenotype of tetL mutants. The changes in expression of citM and genes encoding other ion-coupled solute transporters appear to be adaptive to loss of TetL functions in alkali and Na(+) tolerance, because they reduce Na(+)-coupled solute uptake and enhance solute uptake that is coupled to H(+) entry.
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Affiliation(s)
- Yi Wei
- Department of Pharmacology and Biological Chemistry, Box 1603, Mount Sinai School of Medicine of New York University, New York, NY 10029, USA
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Lerondel G, Doan T, Zamboni N, Sauer U, Aymerich S. YtsJ has the major physiological role of the four paralogous malic enzyme isoforms in Bacillus subtilis. J Bacteriol 2006; 188:4727-36. [PMID: 16788182 PMCID: PMC1482987 DOI: 10.1128/jb.00167-06] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The Bacillus subtilis genome contains several sets of paralogs. An extreme case is the four putative malic enzyme genes maeA, malS, ytsJ, and mleA. maeA was demonstrated to encode malic enzyme activity, to be inducible by malate, but also to be dispensable for growth on malate. We report systematic experiments to test whether these four genes ensure backup or cover different functions. Analysis of single- and multiple-mutant strains demonstrated that ytsJ has a major physiological role in malate utilization for which none of the other three genes could compensate. In contrast, maeA, malS, and mleA had distinct roles in malate utilization for which they could compensate one another. The four proteins exhibited malic enzyme activity; MalS, MleA, and MaeA exhibited 4- to 90-fold higher activities with NAD+ than with NADP+. YtsJ activity, in contrast, was 70-fold higher with NADP+ than with NAD+, with Km values of 0.055 and 2.8 mM, respectively. lacZ fusions revealed strong transcription of ytsJ, twofold higher in malate than in glucose medium, but weak transcription of malS and mleA. In contrast, mleA was strongly transcribed in complex medium. Metabolic flux analysis confirmed the major role of YtsJ in malate-to-pyruvate interconversion. While overexpression of the NADP-dependent Escherichia coli malic enzyme MaeB did not suppress the growth defect of a ytsJ mutant on malate, overexpression of the transhydrogenase UdhA from E. coli partially suppressed it. These results suggest an additional physiological role of YtsJ beyond that of malate-to-pyruvate conversion.
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Affiliation(s)
- Guillaume Lerondel
- Microbiologie et Génétique Moléculaire, INRA (UMR1238) CNRS (UMR2585) and INAP-G, F-78850 Thiverval-Grignon, France
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Sobczak I, Lolkema JS. The 2-hydroxycarboxylate transporter family: physiology, structure, and mechanism. Microbiol Mol Biol Rev 2006; 69:665-95. [PMID: 16339740 PMCID: PMC1306803 DOI: 10.1128/mmbr.69.4.665-695.2005] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The 2-hydroxycarboxylate transporter family is a family of secondary transporters found exclusively in the bacterial kingdom. They function in the metabolism of the di- and tricarboxylates malate and citrate, mostly in fermentative pathways involving decarboxylation of malate or oxaloacetate. These pathways are found in the class Bacillales of the low-CG gram-positive bacteria and in the gamma subdivision of the Proteobacteria. The pathways have evolved into a remarkable diversity in terms of the combinations of enzymes and transporters that built the pathways and of energy conservation mechanisms. The transporter family includes H+ and Na+ symporters and precursor/product exchangers. The proteins consist of a bundle of 11 transmembrane helices formed from two homologous domains containing five transmembrane segments each, plus one additional segment at the N terminus. The two domains have opposite orientations in the membrane and contain a pore-loop or reentrant loop structure between the fourth and fifth transmembrane segments. The two pore-loops enter the membrane from opposite sides and are believed to be part of the translocation site. The binding site is located asymmetrically in the membrane, close to the interface of membrane and cytoplasm. The binding site in the translocation pore is believed to be alternatively exposed to the internal and external media. The proposed structure of the 2HCT transporters is different from any known structure of a membrane protein and represents a new structural class of secondary transporters.
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Affiliation(s)
- Iwona Sobczak
- Molecular Microbiology, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Kerklaan 30, 9751 NN Haren, The Netherlands
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Fujisawa M, Kusumoto A, Wada Y, Tsuchiya T, Ito M. NhaK, a novel monovalent cation/H+ antiporter of Bacillus subtilis. Arch Microbiol 2005; 183:411-20. [PMID: 16021482 DOI: 10.1007/s00203-005-0011-6] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2005] [Revised: 05/13/2005] [Accepted: 05/17/2005] [Indexed: 10/25/2022]
Abstract
Four Na+/H+ antiporters, Mrp, TetA(L), NhaC, and MleN have so far been described in Bacillus subtilis 168. We identified an additional Na+/H+ antiporter, YvgP, from B. subtilis that exhibits homology to the cation: proton antiporter-1 (CPA-1) family. The yvgP-dependent complementation observed in a Na+(Ca2+)/H+ antiporter-defective Escherichia coli mutant (KNabc) suggested that YvgP effluxed Na+ and Li+. In addition, effects of yvgP expression on a K+ uptake-defective mutant of E. coli indicated that YvgP also supported K+ efflux. In a fluorescence-based assay of everted membrane vesicles prepared from E. coli KNabc transformants, YvgP-dependent Na+ (K+, Li+, Rb+)/H+ antiport activity was demonstrated. Na+ (K+, Li+)/H+ activity was higher at pH 8.5 than at pH 7.5. Mg2+, Ca2+ and Mn2+ did not serve as substrates but they inhibited YvgP antiport activities. Studies of yvgP expression in B. subtilis, using a reporter gene fusion, showed a significant constitutive level of expression that was highest in stationary phase, increasing as stationary phase progressed. In addition, the expression level was significantly increased in the presence of added K+ and Na+.
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Affiliation(s)
- Makoto Fujisawa
- Graduate School of Life Sciences, Toyo University, 1-1-1 Izumino, Itakura-machi, Oura-gun, Gunma, 374-0193, Japan
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Padan E, Bibi E, Ito M, Krulwich TA. Alkaline pH homeostasis in bacteria: new insights. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2005; 1717:67-88. [PMID: 16277975 PMCID: PMC3072713 DOI: 10.1016/j.bbamem.2005.09.010] [Citation(s) in RCA: 475] [Impact Index Per Article: 25.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/03/2005] [Revised: 08/19/2005] [Accepted: 09/07/2005] [Indexed: 10/25/2022]
Abstract
The capacity of bacteria to survive and grow at alkaline pH values is of widespread importance in the epidemiology of pathogenic bacteria, in remediation and industrial settings, as well as in marine, plant-associated and extremely alkaline ecological niches. Alkali-tolerance and alkaliphily, in turn, strongly depend upon mechanisms for alkaline pH homeostasis, as shown in pH shift experiments and growth experiments in chemostats at different external pH values. Transcriptome and proteome analyses have recently complemented physiological and genetic studies, revealing numerous adaptations that contribute to alkaline pH homeostasis. These include elevated levels of transporters and enzymes that promote proton capture and retention (e.g., the ATP synthase and monovalent cation/proton antiporters), metabolic changes that lead to increased acid production, and changes in the cell surface layers that contribute to cytoplasmic proton retention. Targeted studies over the past decade have followed up the long-recognized importance of monovalent cations in active pH homeostasis. These studies show the centrality of monovalent cation/proton antiporters in this process while microbial genomics provides information about the constellation of such antiporters in individual strains. A comprehensive phylogenetic analysis of both eukaryotic and prokaryotic genome databases has identified orthologs from bacteria to humans that allow better understanding of the specific functions and physiological roles of the antiporters. Detailed information about the properties of multiple antiporters in individual strains is starting to explain how specific monovalent cation/proton antiporters play dominant roles in alkaline pH homeostasis in cells that have several additional antiporters catalyzing ostensibly similar reactions. New insights into the pH-dependent Na(+)/H(+) antiporter NhaA that plays an important role in Escherichia coli have recently emerged from the determination of the structure of NhaA. This review highlights the approaches, major findings and unresolved problems in alkaline pH homeostasis, focusing on the small number of well-characterized alkali-tolerant and extremely alkaliphilic bacteria.
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Affiliation(s)
- Etana Padan
- Alexander Silberman Institute of Life Sciences, Hebrew University, Jerusalem 91904, Israel.
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Krulwich TA, Lewinson O, Padan E, Bibi E. Do physiological roles foster persistence of drug/multidrug-efflux transporters? A case study. Nat Rev Microbiol 2005; 3:566-72. [PMID: 15953929 DOI: 10.1038/nrmicro1181] [Citation(s) in RCA: 73] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Drug and multidrug resistance have greatly compromised the compounds that were once the mainstays of antibiotic therapy. This resistance often persists despite reductions in the use of antibiotics, indicating that the proteins encoded by antibiotic-resistance genes have alternative physiological roles that can foster such persistence in the absence of selective pressure by antibiotics. The recent observations that Tet(L), a tetracycline-efflux transporter, and MdfA, a multidrug-efflux transporter, both confer alkali tolerance offer a striking case study in support of this hypothesis.
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Affiliation(s)
- Terry A Krulwich
- Department of Pharmacology and Biological Chemistry, Mount Sinai School of Medicine, New York, New York 10029, USA
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Lolkema JS, Sobczak I, Slotboom DJ. Secondary transporters of the 2HCT family contain two homologous domains with inverted membrane topology and trans re-entrant loops. FEBS J 2005; 272:2334-44. [PMID: 15853816 DOI: 10.1111/j.1742-4658.2005.04665.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
The 2-hydroxycarboxylate transporter (2HCT) family of secondary transporters belongs to a much larger structural class of secondary transporters termed ST3 which contains about 2000 transporters in 32 families. The transporters of the 2HCT family are among the best studied in the class. Here we detect weak sequence similarity between the N- and C-terminal halves of the proteins using a sensitive method which uses a database containing the N- and C-terminal halves of all the sequences in ST3 and involves blast searches of each sequence in the database against the whole database. Unrelated families of secondary transporters of the same length and composition were used as controls. The sequence similarity involved major parts of the N- and C-terminal halves and not just a small stretch. The membrane topology of the homologous N- and C-terminal domains was deduced from the experimentally determined topology of the members of the 2HCT family. The domains consist of five transmembrane segments each and have opposite orientations in the membrane. The N terminus of the N-terminal domain is extracellular, while the N terminus of the C-terminal domain is cytoplasmic. The loops between the fourth and fifth transmembrane segment in each domain are well conserved throughout the class and contain a high fraction of residues with small side chains, Gly, Ala and Ser. Experimental work on the citrate transporter CitS in the 2HCT family indicates that the loops are re-entrant or pore loops. The re-entrant loops in the N- and C-terminal domains enter the membrane from opposite sides (trans-re-entrant loops). The combination of inverted membrane topology and trans-re-entrant loops represents a new fold for secondary transporters and resembles the structure of aquaporins and models proposed for Na+/Ca2+ exchangers.
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Affiliation(s)
- Juke S Lolkema
- Molecular Microbiology, Biomolecular Sciences and Biotechnology Institute, University of Groningen, the Netherlands.
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Sauer U, Eikmanns BJ. The PEP-pyruvate-oxaloacetate node as the switch point for carbon flux distribution in bacteria. FEMS Microbiol Rev 2004; 29:765-94. [PMID: 16102602 DOI: 10.1016/j.femsre.2004.11.002] [Citation(s) in RCA: 358] [Impact Index Per Article: 17.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2004] [Revised: 10/27/2004] [Accepted: 11/01/2004] [Indexed: 11/16/2022] Open
Abstract
In many organisms, metabolite interconversion at the phosphoenolpyruvate (PEP)-pyruvate-oxaloacetate node involves a structurally entangled set of reactions that interconnects the major pathways of carbon metabolism and thus, is responsible for the distribution of the carbon flux among catabolism, anabolism and energy supply of the cell. While sugar catabolism proceeds mainly via oxidative or non-oxidative decarboxylation of pyruvate to acetyl-CoA, anaplerosis and the initial steps of gluconeogenesis are accomplished by C3- (PEP- and/or pyruvate-) carboxylation and C4- (oxaloacetate- and/or malate-) decarboxylation, respectively. In contrast to the relatively uniform central metabolic pathways in bacteria, the set of enzymes at the PEP-pyruvate-oxaloacetate node represents a surprising diversity of reactions. Variable combinations are used in different bacteria and the question of the significance of all these reactions for growth and for biotechnological fermentation processes arises. This review summarizes what is known about the enzymes and the metabolic fluxes at the PEP-pyruvate-oxaloacetate node in bacteria, with a particular focus on the C3-carboxylation and C4-decarboxylation reactions in Escherichia coli, Bacillus subtilis and Corynebacterium glutamicum. We discuss the activities of the enzymes, their regulation and their specific contribution to growth under a given condition or to biotechnological metabolite production. The present knowledge unequivocally reveals the PEP-pyruvate-oxaloacetate nodes of bacteria to be a fascinating target of metabolic engineering in order to achieve optimized metabolite production.
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Affiliation(s)
- Uwe Sauer
- Institute of Biotechnology, ETH Zürich, Switzerland
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Rodionov DA, Vitreschak AG, Mironov AA, Gelfand MS. Comparative genomics of the methionine metabolism in Gram-positive bacteria: a variety of regulatory systems. Nucleic Acids Res 2004; 32:3340-53. [PMID: 15215334 PMCID: PMC443535 DOI: 10.1093/nar/gkh659] [Citation(s) in RCA: 133] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Regulation of the methionine biosynthesis and transport genes in bacteria is rather diverse and involves two RNA-level regulatory systems and at least three DNA-level systems. In particular, the methionine metabolism in Gram-positive bacteria was known to be controlled by the S-box and T-box mechanisms, both acting on the level of premature termination of transcription. Using comparative analysis of genes, operons and regulatory elements, we described the methionine metabolic pathway and the methionine regulons in available genomes of Gram-positive bacteria. A large number of methionine-specific RNA elements were identified. S-boxes were shown to be widely distributed in Bacillales and Clostridia, whereas methionine-specific T-boxes occurred mostly in Lactobacillales. A candidate binding signal (MET-box) for a hypothetical methionine regulator, possibly MtaR, was identified in Streptococcaceae, the only family in the Bacillus/Clostridium group of Gram-positive bacteria having neither S-boxes, nor methionine-specific T-boxes. Positional analysis of methionine-specific regulatory sites complemented by genome context analysis lead to identification of new members of the methionine regulon, both enzymes and transporters, and reconstruction of the methionine metabolism in various bacterial genomes. In particular, we found candidate transporters for methionine (MetT) and methylthioribose (MtnABC), as well as new enzymes forming the S-adenosylmethionine recycling pathway. Methionine biosynthetic enzymes in various bacterial species are quite variable. In particular, Oceanobacillus iheyensis possibly uses a homolog of the betaine-homocysteine methyltransferase bhmT gene from vertebrates to substitute missing bacterial-type methionine synthases.
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Affiliation(s)
- Dmitry A Rodionov
- Institute for Information Transmission Problems, Russian Academy of Sciences, Bolshoi Karetny pereulok 19, Moscow 127994, Russia.
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Prakash S, Cooper G, Singhi S, Saier MH. The ion transporter superfamily. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2004; 1618:79-92. [PMID: 14643936 DOI: 10.1016/j.bbamem.2003.10.010] [Citation(s) in RCA: 92] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
We define a novel superfamily of secondary carriers specific for cationic and anionic compounds, which we have termed the ion transporter (IT) superfamily. Twelve recognized and functionally defined families constitute this superfamily. We provide statistical sequence analyses demonstrating that these families were in fact derived from a common ancestor. Further, we characterize the 12 families in terms of (1) the known substrates transported, (2) the modes of transport and energy coupling mechanisms used, (3) the family sizes (in numbers of sequenced protein members in the current NCBI database), (4) the organismal distributions of the members of each family, (5) the size ranges of the constituent proteins, (6) the predicted topologies of these proteins, and (7) the occurrence of non-homologous auxiliary proteins that may either facilitate or be required for transport. No member of the superfamily is known to function in a capacity other than transport. Proteins in several of the constituent families are shown to have arisen by tandem intragenic duplication events, but topological variation has resulted from a variety of dissimilar genetic fusion, splicing and insertional events. The evolutionary relationships between the members of each family are defined, leading to predictions of functionally relevant orthologous relationships. Some but not all of the families include functionally dissimilar paralogues that arose by early extragenic duplication events.
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Affiliation(s)
- Shraddha Prakash
- Division of Biological Sciences, University of California at San Diego, La Jolla, CA 92093-0116, USA
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Doan T, Servant P, Tojo S, Yamaguchi H, Lerondel G, Yoshida KI, Fujita Y, Aymerich S. The Bacillus subtilis ywkA gene encodes a malic enzyme and its transcription is activated by the YufL/YufM two-component system in response to malate. MICROBIOLOGY (READING, ENGLAND) 2003; 149:2331-2343. [PMID: 12949160 DOI: 10.1099/mic.0.26256-0] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
A transcriptome comparison of a wild-type Bacillus subtilis strain growing under glycolytic or gluconeogenic conditions was performed. In particular, it revealed that the ywkA gene, one of the four paralogues putatively encoding a malic enzyme, was more transcribed during gluconeogenesis. Using a lacZ reporter fusion to the ywkA promoter, it was shown that ywkA was specifically induced by external malate and not subject to glucose catabolite repression. Northern analysis confirmed this expression pattern and demonstrated that ywkA is cotranscribed with the downstream ywkB gene. The ywkA gene product was purified and biochemical studies demonstrated its malic enzyme activity, which was 10-fold higher with NAD than with NADP (kcat/Km 102 and 10 s(-1) mM(-1), respectively). However, physiological tests with single and multiple mutant strains affected in ywkA and/or in ywkA paralogues showed that ywkA does not contribute to efficient utilization of malate for growth. Transposon mutagenesis allowed the identification of the uncharacterized YufL/YufM two-component system as being responsible for the control of ywkA expression. Genetic analysis and in vitro studies with purified YufM protein showed that YufM binds just upstream of ywkA promoter and activates ywkA transcription in response to the presence of malate in the extracellular medium, transmitted by YufL. ywkA and yufL/yufM could thus be renamed maeA for malic enzyme and malK/malR for malate kinase sensor/malate response regulator, respectively.
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Affiliation(s)
- Thierry Doan
- Génétique Moléculaire et Cellulaire, INRA (UMR216) CNRS (URA1925) and INAP-G, F-78850 Thiverval-Grignon, France
| | - Pascale Servant
- Génétique Moléculaire et Cellulaire, INRA (UMR216) CNRS (URA1925) and INAP-G, F-78850 Thiverval-Grignon, France
| | - Shigeo Tojo
- Department of Biotechnology, Fukuyama University, 985 Sanzo, Higashimura, Fukuyama, Japan
| | - Hirotake Yamaguchi
- Department of Biotechnology, Fukuyama University, 985 Sanzo, Higashimura, Fukuyama, Japan
| | - Guillaume Lerondel
- Génétique Moléculaire et Cellulaire, INRA (UMR216) CNRS (URA1925) and INAP-G, F-78850 Thiverval-Grignon, France
| | - Ken-Ichi Yoshida
- Department of Biotechnology, Fukuyama University, 985 Sanzo, Higashimura, Fukuyama, Japan
| | - Yasutaro Fujita
- Department of Biotechnology, Fukuyama University, 985 Sanzo, Higashimura, Fukuyama, Japan
| | - Stéphane Aymerich
- Génétique Moléculaire et Cellulaire, INRA (UMR216) CNRS (URA1925) and INAP-G, F-78850 Thiverval-Grignon, France
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Tanaka K, Kobayashi K, Ogasawara N. The Bacillus subtilis YufLM two-component system regulates the expression of the malate transporters MaeN (YufR) and YflS, and is essential for utilization of malate in minimal medium. MICROBIOLOGY (READING, ENGLAND) 2003; 149:2317-2329. [PMID: 12949159 DOI: 10.1099/mic.0.26257-0] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The Gram-positive bacterium Bacillus subtilis has a complete set of enzymes for the tricarboxylic acid (TCA) cycle and can grow aerobically using most of the TCA cycle intermediates (malate, fumarate, succinate and citrate) as a sole carbon source. The B. subtilis genome sequence contains three paralogous two-component regulatory systems, CitST, DctSR and YufLM. CitST and DctSR activate the expression of a transporter of the Mg(2+)-citrate complex (CitM) and a fumarate and succinate transporter (DctP), respectively. These findings prompted an investigation of whether the YufL sensor and its cognate regulator, YufM, play a role in malate uptake. This paper reports that the YufM regulator shows in vitro binding to the promoter region of two malate transporter genes, maeN and yflS, and is responsible for inducing their expression in vivo. It was also found that inactivation of the yufM or maeN genes resulted in bacteria that could not grow in a minimal salts medium containing malate as a sole carbon source, indicating that the induction of the MaeN transporter by the YufM regulator is essential for the utilization of malate as a carbon source. Inactivation of the yufL gene resulted in the constitutive expression of MaeN. This expression was suppressed by reintroduction of the kinase domain of YufL, indicating that the YufL sensor is required for proper signal detection and signalling specificity. The authors propose that a phosphatase activity of YufL plays an important role in the YufLM two-component regulatory system. The studies reported here have revealed that members of a set of paralogous two-component regulatory systems in B. subtilis, CitST, DctSR and YufLM, are involved in a related function--uptake (and metabolism) of the TCA cycle intermediates--but with distinct substrate specificities.
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Affiliation(s)
- Kousei Tanaka
- Department of Bioinformatics and Genomics, Graduate School of Information Science, Nara Institute of Science and Technology, 8916-5, Takayama, Ikoma, Nara 630-0101, Japan
| | - Kazuo Kobayashi
- Department of Bioinformatics and Genomics, Graduate School of Information Science, Nara Institute of Science and Technology, 8916-5, Takayama, Ikoma, Nara 630-0101, Japan
| | - Naotake Ogasawara
- Department of Bioinformatics and Genomics, Graduate School of Information Science, Nara Institute of Science and Technology, 8916-5, Takayama, Ikoma, Nara 630-0101, Japan
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Lolkema JS, Slotboom DJ. Classification of 29 families of secondary transport proteins into a single structural class using hydropathy profile analysis. J Mol Biol 2003; 327:901-9. [PMID: 12662917 DOI: 10.1016/s0022-2836(03)00214-6] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
A classification scheme for membrane proteins is proposed that clusters families of proteins into structural classes based on hydropathy profile analysis. The averaged hydropathy profiles of protein families are taken as fingerprints of the 3D structure of the proteins and, therefore, are able to detect more distant evolutionary relationships than amino acid sequences. A procedure was developed in which hydropathy profile analysis is used initially as a filter in a BLAST search of the NCBI protein database. The strength of the procedure is demonstrated by the classification of 29 families of secondary transporters into a single structural class, termed ST[3]. An exhaustive search of the database revealed that the 29 families contain 568 unique sequences. The proteins are predominantly from prokaryotic origin and most of the characterized transporters in ST[3] transport organic and inorganic anions and a smaller number are Na(+)/H(+) antiporters. All modes of energy coupling (symport, antiport, uniport) are found in structural class ST[3]. The relevance of the classification for structure/function prediction of uncharacterised transporters in the class is discussed.
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Affiliation(s)
- Juke S Lolkema
- Molecular Microbiology, Biomolecular Sciences and Biotechnology Institute, University of Groningen, Kerklaan 30, 9751NN, Haren, The Netherlands.
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Herz K, Vimont S, Padan E, Berche P. Roles of NhaA, NhaB, and NhaD Na+/H+ antiporters in survival of Vibrio cholerae in a saline environment. J Bacteriol 2003; 185:1236-44. [PMID: 12562793 PMCID: PMC142861 DOI: 10.1128/jb.185.4.1236-1244.2003] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Vibrio cholerae, the causative agent of cholera, is a normal inhabitant of aquatic environments, where it survives in a wide range of conditions of pH and salinity. In this work, we investigated the role of three Na+/H+ antiporters on the survival of V. cholerae in a saline environment. We have previously cloned the Vc-nhaA gene encoding the V. cholerae homolog of Escherichia coli. Here we identified two additional antiporter genes, designated Vc-nhaB and Vc-nhaD, encoding two putative proteins of 530 and 477 residues, respectively, highly homologous to the respective antiporters of Vibrio species and E. coli. We showed that both Vc-NhaA and Vc-NhaB confer Na+ resistance and that Vc-NhaA displays an antiport activity in E. coli, which is similar in magnitude, kinetic parameters, and pH regulation to that of E. coli NhaA. To determine the roles of the Na+/H+ antiporters in V. cholerae, we constructed nhaA, nhaB, and nhaD mutants (single, double, and triple mutants). In contrast to E. coli, the inactivation of the three putative antiporter genes (Vc-nhaABD) in V. cholerae did not alter the bacterial exponential growth in the presence of high Na+ concentrations and had only a slight effect in the stationary phase. In contrast, a pronounced and similar Li+-sensitive phenotype was found with all mutants lacking Vc-nhaA during the exponential phase of growth and also with the triple mutant in the stationary phase of growth. By using 2-n-nonyl-4-hydroxyquinoline N-oxide, a specific inhibitor of the electron-transport-linked Na+ pump NADH-quinone oxidoreductase (NQR), we determined that in the absence of NQR activity, the Vc-NhaA Na+/H+ antiporter activity becomes essential for the resistance of V. cholerae to Na+ at alkaline pH. Since the ion pump NQR is Na+ specific, we suggest that its activity masks the Na+/H+ but not the Li+/H+ antiporter activities. Our results indicate that the Na+ resistance of the human pathogen V. cholerae requires a complex molecular system involving multiple antiporters and the NQR pump.
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Affiliation(s)
- Katia Herz
- Department of Microbial and Molecular Ecology, Institute of Life Sciences, The Hebrew University of Jerusalem, 91904 Jerusalem, Israel
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Warner JB, Lolkema JS. Growth of Bacillus subtilis on citrate and isocitrate is supported by the Mg2+-citrate transporter CitM. MICROBIOLOGY (READING, ENGLAND) 2002; 148:3405-3412. [PMID: 12427932 DOI: 10.1099/00221287-148-11-3405] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Bacillus subtilis 168 was assayed for its growth on tricarboxylic acid (TCA) cycle intermediates and related compounds as the sole carbon sources. Growth of the organism was supported by citrate, D-isocitrate, succinate, fumarate and L-malate, whereas no growth was observed in the presence of cis-aconitate,2-oxoglutarate, D-malate, oxaloacetate and tricarballylate. Growth of the organism on the tricarboxylates citrate and D-isocitrate required the presence of functional CitM, an Mg(2+)-citrate transporter, whereas its growth on succinate, fumarate and L-malate appeared to be CitM-independent. Interestingly, the naturally occurring enantiomer D-isocitrate was favoured over L-isocitrate by the organism. Like citrate, D-isocitrate was shown to be an inducer of citM expression in B. subtilis. The addition of 1 mM Mg(2+) to the growth medium improved growth of the organism on both citrate and D-isocitrate, suggesting that D-isocitrate was taken up by CitM in complex with divalent metal ions. Subsequently, the ability of CitM to transport D-isocitrate was demonstrated by competition experiments and by heterologous exchange in right-side-out membrane vesicles prepared from E. coli cells expressing citM. None of the other TCA cycle intermediates and related compounds tested were recognized by CitM. Uptake experiments using radioactive (63)Ni(2+) provided direct evidence that D-isocitrate is transported in complex with divalent metal ions.
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Affiliation(s)
- Jessica B Warner
- Molecular Microbiology, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Kerklaan 30, 9751 NN Haren, The Netherlands1
| | - Juke S Lolkema
- Molecular Microbiology, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Kerklaan 30, 9751 NN Haren, The Netherlands1
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