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Yang T, Nian Y, Lin H, Li J, Lin X, Li T, Wang R, Wang L, Beattie GA, Zhang J, Fan M. Structure and mechanism of the osmoregulated choline transporter BetT. SCIENCE ADVANCES 2024; 10:eado6229. [PMID: 39141726 PMCID: PMC11323884 DOI: 10.1126/sciadv.ado6229] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/12/2024] [Accepted: 07/09/2024] [Indexed: 08/16/2024]
Abstract
The choline-glycine betaine pathway plays an important role in bacterial survival in hyperosmotic environments. Osmotic activation of the choline transporter BetT promotes the uptake of external choline for synthesizing the osmoprotective glycine betaine. Here, we report the cryo-electron microscopy structures of Pseudomonas syringae BetT in the apo and choline-bound states. Our structure shows that BetT forms a domain-swapped trimer with the C-terminal domain (CTD) of one protomer interacting with the transmembrane domain (TMD) of a neighboring protomer. The substrate choline is bound within a tryptophan prism at the central part of TMD. Together with functional characterization, our results suggest that in Pseudomonas species, including the plant pathogen P. syringae and the human pathogen Pseudomonas aeruginosa, BetT is locked at a low-activity state through CTD-mediated autoinhibition in the absence of osmotic stress, and its hyperosmotic activation involves the release of this autoinhibition.
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Affiliation(s)
- Tianjiao Yang
- CAS Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai 200032, China
- University of Chinese Academy of Sciences, Beijing 101408, China
| | - Yuwei Nian
- CAS Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai 200032, China
| | - Huajian Lin
- CAS Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai 200032, China
| | - Jing Li
- School of Pharmaceutical Sciences, Wuhan University, Wuhan 430071, China
| | - Xiang Lin
- State Key Laboratory of Genetic Engineering, Collaborative Innovation Center of Genetics and Development, Department of Biochemistry and Biophysics, School of Life Sciences, Fudan University, Shanghai 200438, China
| | - Tianming Li
- CAS Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai 200032, China
| | - Ruiying Wang
- CAS Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai 200032, China
| | - Longfei Wang
- School of Pharmaceutical Sciences, Wuhan University, Wuhan 430071, China
| | - Gwyn A. Beattie
- Department of Plant Pathology, Entomology and Microbiology, Iowa State University, Ames, IA 50011, USA
| | - Jinru Zhang
- State Key Laboratory of Genetic Engineering, Collaborative Innovation Center of Genetics and Development, Department of Biochemistry and Biophysics, School of Life Sciences, Fudan University, Shanghai 200438, China
| | - Minrui Fan
- CAS Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai 200032, China
- Key Laboratory of Plant Carbon Capture, Chinese Academy of Sciences, Shanghai 200032, China
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Mondal N, Roy C, Chatterjee S, Sarkar J, Dutta S, Bhattacharya S, Chakraborty R, Ghosh W. Thermal Endurance by a Hot-Spring-Dwelling Phylogenetic Relative of the Mesophilic Paracoccus. Microbiol Spectr 2022; 10:e0160622. [PMID: 36287077 PMCID: PMC9769624 DOI: 10.1128/spectrum.01606-22] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2022] [Accepted: 09/24/2022] [Indexed: 01/05/2023] Open
Abstract
High temperature growth/survival was revealed in a phylogenetic relative (SMMA_5) of the mesophilic Paracoccus isolated from the 78 to 85°C water of a Trans-Himalayan sulfur-borax spring. After 12 h at 50°C, or 45 min at 70°C, in mineral salts thiosulfate (MST) medium, SMMA_5 retained ~2% colony forming units (CFUs), whereas comparator Paracoccus had 1.5% and 0% CFU left at 50°C and 70°C, respectively. After 12 h at 50°C, the thermally conditioned sibling SMMA_5_TC exhibited an ~1.5 time increase in CFU count; after 45 min at 70°C, SMMA_5_TC had 7% of the initial CFU count. 1,000-times diluted Reasoner's 2A medium, and MST supplemented with lithium, boron, or glycine-betaine, supported higher CFU-retention/CFU-growth than MST. Furthermore, with or without lithium/boron/glycine-betaine, a higher percentage of cells always remained metabolically active, compared with what percentage formed single colonies. SMMA_5, compared with other Paracoccus, contained 335 unique genes: of these, 186 encoded hypothetical proteins, and 83 belonged to orthology groups, which again corresponded mostly to DNA replication/recombination/repair, transcription, secondary metabolism, and inorganic ion transport/metabolism. The SMMA_5 genome was relatively enriched in cell wall/membrane/envelope biogenesis, and amino acid metabolism. SMMA_5 and SMMA_5_TC mutually possessed 43 nucleotide polymorphisms, of which 18 were in protein-coding genes with 13 nonsynonymous and seven radical amino acid replacements. Such biochemical and biophysical mechanisms could be involved in thermal stress mitigation which streamline the cells' energy and resources toward system-maintenance and macromolecule-stabilization, thereby relinquishing cell-division for cell-viability. Thermal conditioning apparently helped inherit those potential metabolic states which are crucial for cell-system maintenance, while environmental solutes augmented the indigenous stability-conferring mechanisms. IMPORTANCE For a holistic understanding of microbial life's high-temperature adaptation, it is imperative to explore the biology of the phylogenetic relatives of mesophilic bacteria which get stochastically introduced to geographically and geologically diverse hot spring systems by local geodynamic forces. Here, in vitro endurance of high heat up to the extent of growth under special (habitat-inspired) conditions was discovered in a hot-spring-dwelling phylogenetic relative of the mesophilic Paracoccus species. Thermal conditioning, extreme oligotrophy, metabolic deceleration, presence of certain habitat-specific inorganic/organic solutes, and potential genomic specializations were found to be the major enablers of this conditional (acquired) thermophilicity. Feasibility of such phenomena across the taxonomic spectrum can well be paradigm changing for the established scopes of microbial adaptation to the physicochemical extremes. Applications of conditional thermophilicity in microbial process biotechnology may be far reaching and multifaceted.
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Affiliation(s)
- Nibendu Mondal
- Department of Microbiology, Bose Institute, Kolkata, India
| | - Chayan Roy
- Department of Microbiology, Bose Institute, Kolkata, India
| | | | | | - Subhajit Dutta
- Department of Microbiology, Bose Institute, Kolkata, India
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Csitári B, Bedics A, Felföldi T, Boros E, Nagy H, Máthé I, Székely AJ. Anion-type modulates the effect of salt stress on saline lake bacteria. Extremophiles 2022; 26:12. [PMID: 35137260 PMCID: PMC8825391 DOI: 10.1007/s00792-022-01260-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2021] [Accepted: 01/10/2022] [Indexed: 11/29/2022]
Abstract
Beside sodium chloride, inland saline aquatic systems often contain other anions than chloride such as hydrogen carbonate and sulfate. Our understanding of the biological effects of salt composition diversity is limited; therefore, the aim of this study was to examine the effect of different anions on the growth of halophilic bacteria. Accordingly, the salt composition and concentration preference of 172 strains isolated from saline and soda lakes that differed in ionic composition was tested using media containing either carbonate, chloride or sulfate as anion in concentration values ranging from 0 to 0.40 mol/L. Differences in salt-type preference among bacterial strains were observed in relationship to the salt composition of the natural habitat they were isolated from indicating specific salt-type adaptation. Sodium carbonate represented the strongest selective force, while majority of strains was well-adapted to growth even at high concentrations of sodium sulfate. Salt preference was to some extent associated with taxonomy, although variations even within the same bacterial species were also identified. Our results suggest that the extent of the effect of dissolved salts in saline lakes is not limited to their concentration but the type of anion also substantially impacts the growth and survival of individual microorganisms.
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Affiliation(s)
- Bianka Csitári
- Department of Microbiology, ELTE Eötvös Loránd University, Pázmány Péter stny. 1/c, 1117, Budapest, Hungary
- Department of Ecology and Genetics/Limnology, Uppsala University EBC, Norbyvägen 18D, 75236, Uppsala, Sweden
- Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, Solnavägen 9, 17165, Stockholm, Sweden
| | - Anna Bedics
- Department of Microbiology, ELTE Eötvös Loránd University, Pázmány Péter stny. 1/c, 1117, Budapest, Hungary
- Depatment of Molecular Ecology, Institute of Aquaculture and Environmental Safety, Hungarian University of Agriculture and Life Sciences, Páter Károly utca 1, 2100, Gödöllő, Hungary
| | - Tamás Felföldi
- Department of Microbiology, ELTE Eötvös Loránd University, Pázmány Péter stny. 1/c, 1117, Budapest, Hungary
- Institute of Aquatic Ecology, Centre for Ecological Research, Karolina u. 29, 1113, Budapest, Hungary
| | - Emil Boros
- Institute of Aquatic Ecology, Centre for Ecological Research, Karolina u. 29, 1113, Budapest, Hungary
| | - Hajnalka Nagy
- Department of Microbiology, ELTE Eötvös Loránd University, Pázmány Péter stny. 1/c, 1117, Budapest, Hungary
| | - István Máthé
- Department of Bioengineering, Sapientia Hungarian University of Transylvania, Piaţa Libertăţii 1, 530104, Miercurea Ciuc, Romania
| | - Anna J Székely
- Department of Ecology and Genetics/Limnology, Uppsala University EBC, Norbyvägen 18D, 75236, Uppsala, Sweden.
- Department of Aquatic Sciences and Assessment, Swedish University of Agricultural Sciences (SLU), Box 7050, 75007, Uppsala, Sweden.
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Investigating Extracellular DNA Release in Staphylococcus xylosus Biofilm In Vitro. Microorganisms 2021; 9:microorganisms9112192. [PMID: 34835318 PMCID: PMC8617998 DOI: 10.3390/microorganisms9112192] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2021] [Revised: 10/08/2021] [Accepted: 10/19/2021] [Indexed: 12/29/2022] Open
Abstract
Staphylococcus xylosus forms biofilm embedded in an extracellular polymeric matrix. As extracellular DNA (eDNA) resulting from cell lysis has been found in several staphylococcal biofilms, we investigated S. xylosus biofilm in vitro by a microscopic approach and identified the mechanisms involved in cell lysis by a transcriptomic approach. Confocal laser scanning microscopy (CLSM) analyses of the biofilms, together with DNA staining and DNase treatment, revealed that eDNA constituted an important component of the matrix. This eDNA resulted from cell lysis by two mechanisms, overexpression of phage-related genes and of cidABC encoding a holin protein that is an effector of murein hydrolase activity. This lysis might furnish nutrients for the remaining cells as highlighted by genes overexpressed in nucleotide salvage, in amino sugar catabolism and in inorganic ion transports. Several genes involved in DNA/RNA repair and genes encoding proteases and chaperones involved in protein turnover were up-regulated. Furthermore, S. xylosus perceived osmotic and oxidative stresses and responded by up-regulating genes involved in osmoprotectant synthesis and in detoxification. This study provides new insight into the physiology of S. xylosus in biofilm.
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Tragni V, Cotugno P, De Grassi A, Cavalluzzi MM, Mincuzzi A, Lentini G, Sanzani SM, Ippolito A, Pierri CL. Targeting Penicillium expansum GMC Oxidoreductase with High Affinity Small Molecules for Reducing Patulin Production. BIOLOGY 2020; 10:biology10010021. [PMID: 33396459 PMCID: PMC7824139 DOI: 10.3390/biology10010021] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/25/2020] [Revised: 12/22/2020] [Accepted: 12/27/2020] [Indexed: 12/21/2022]
Abstract
Simple Summary With the urgent necessity of potential treatments for limiting mycotoxin production and postharvest fungal rots, we propose a combined in silico/in vitro/in vivo strategy for the rapid and effective identification of bioactive small molecules, chosen among a chemical library hosting approved drugs and phytochemicals, to be used after harvest. The molecular target of our analysis was the GMC oxidoreductase from Penicillium expansum involved in the biosynthesis of patulin, a mycotoxin that can contaminate many foods, especially fruits and fruit-based products. The employed in silico/in vitro/in vivo assays described in our study proved the effectiveness of our strategy and in particular of two small molecules, 6-hydroxycoumarin (structurally related to umbelliferon, an already characterized patulin synthase inhibitor) and meticrane (an already approved drug) in reducing patulin accumulation. Our findings highly recommend the mentioned ligands to be subjected to further analysis for being used in the next future in place of other more toxic compounds, in postharvest treatments based on dipping or drenching methods. Abstract Flavine adenine dinucleotide (FAD) dependent glucose methanol choline oxidoreductase (GMC oxidoreductase) is the terminal key enzyme of the patulin biosynthetic pathway. GMC oxidoreductase catalyzes the oxidative ring closure of (E)-ascladiol to patulin. Currently, no protein involved in the patulin biosynthesis in Penicillium expansum has been experimentally characterized or solved by X-ray diffraction. Consequently, nothing is known about P. expansum GMC oxidoreductase substrate-binding site and mode of action. In the present investigation, a 3D comparative model for P. expansum GMC oxidoreductase has been described. Furthermore, a multistep computational approach was used to identify P. expansum GMC oxidoreductase residues involved in the FAD binding and in substrate recognition. Notably, the obtained 3D comparative model of P. expansum GMC oxidoreductase was used for performing a virtual screening of a chemical/drug library, which allowed to predict new GMC oxidoreductase high affinity ligands to be tested in in vitro/in vivo assays. In vitro assays performed in presence of 6-hydroxycoumarin and meticrane, among the highly affinity predicted binders, confirmed a dose-dependent inhibition (17–81%) of patulin production by 6-hydroxycoumarin (10 µM–1 mM concentration range), whereas the approved drug meticrane inhibited patulin production by 43% already at 10 µM. Furthermore, 6-hydroxycoumarin and meticrane caused a 60 and 41% reduction of patulin production, respectively, in vivo on apples at 100 µg/wound.
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Affiliation(s)
- Vincenzo Tragni
- Department of Soil, Plant and Food Sciences, University of Bari Aldo Moro, Via Amendola 165/A, 70126 Bari, Italy; (V.T.); (A.M.)
| | - Pietro Cotugno
- Biology Department, University of Bari Aldo Moro, Via Amendola 165/A, 70126 Bari, Italy;
| | - Anna De Grassi
- Laboratory of Biochemistry, Molecular and Structural Biology, Department of Biosciences, Biotechnologies, Biopharmaceutics, University of Bari, Via E. Orabona, 4, 70125 Bari, Italy;
- BROWSer S.r.l., c/o Department of Biosciences, Biotechnologies, Biopharmaceutics, University “Aldo Moro” of Bari, Via E. Orabona, 4, 70126 Bari, Italy
| | - Maria Maddalena Cavalluzzi
- Dipartimento di Farmacia—Scienze del Farmaco, Università degli Studi di Bari Aldo Moro, via Orabona 4, 70125 Bari, Italy; (M.M.C.); (G.L.)
| | - Annamaria Mincuzzi
- Department of Soil, Plant and Food Sciences, University of Bari Aldo Moro, Via Amendola 165/A, 70126 Bari, Italy; (V.T.); (A.M.)
| | - Giovanni Lentini
- Dipartimento di Farmacia—Scienze del Farmaco, Università degli Studi di Bari Aldo Moro, via Orabona 4, 70125 Bari, Italy; (M.M.C.); (G.L.)
| | - Simona Marianna Sanzani
- CIHEAM Bari, Via Ceglie 9, 70010 Valenzano (BA), Italy
- Correspondence: (S.M.S.); (A.I.); ; (C.L.P.); Tel.: +39-0805443614 (C.L.P.); Fax: +39-0805442770 (C.L.P.)
| | - Antonio Ippolito
- Department of Soil, Plant and Food Sciences, University of Bari Aldo Moro, Via Amendola 165/A, 70126 Bari, Italy; (V.T.); (A.M.)
- Correspondence: (S.M.S.); (A.I.); ; (C.L.P.); Tel.: +39-0805443614 (C.L.P.); Fax: +39-0805442770 (C.L.P.)
| | - Ciro Leonardo Pierri
- Laboratory of Biochemistry, Molecular and Structural Biology, Department of Biosciences, Biotechnologies, Biopharmaceutics, University of Bari, Via E. Orabona, 4, 70125 Bari, Italy;
- BROWSer S.r.l., c/o Department of Biosciences, Biotechnologies, Biopharmaceutics, University “Aldo Moro” of Bari, Via E. Orabona, 4, 70126 Bari, Italy
- Correspondence: (S.M.S.); (A.I.); ; (C.L.P.); Tel.: +39-0805443614 (C.L.P.); Fax: +39-0805442770 (C.L.P.)
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Casey D, Sleator RD. A genomic analysis of osmotolerance in Staphylococcus aureus. Gene 2020; 767:145268. [PMID: 33157201 DOI: 10.1016/j.gene.2020.145268] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2020] [Revised: 09/07/2020] [Accepted: 10/20/2020] [Indexed: 12/12/2022]
Abstract
A key phenotypic characteristic of the Gram-positive bacterial pathogen, Staphylococcus aureus, is its ability to grow in low aw environments. A homology transfer based approach, using the well characterised osmotic stress response systems of Bacillus subtilis and Escherichia coli, was used to identify putative osmotolerance loci in Staphylococcus aureus ST772-MRSA-V. A total of 17 distinct putative hyper and hypo-osmotic stress response systems, comprising 78 genes, were identified. The ST772-MRSA-V genome exhibits significant degeneracy in terms of the osmotic stress response; with three copies of opuD, two copies each of nhaK and mrp/mnh, and five copies of opp. Furthermore, regulation of osmotolerance in ST772-MRSA-V appears to be mediated at the transcriptional, translational, and post-translational levels.
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Affiliation(s)
- Dylan Casey
- Department of Biological Sciences, Munster Technological University, Bishopstown Campus, Cork, Ireland
| | - Roy D Sleator
- Department of Biological Sciences, Munster Technological University, Bishopstown Campus, Cork, Ireland.
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Ronzheimer S, Warmbold B, Arnhold C, Bremer E. The GbsR Family of Transcriptional Regulators: Functional Characterization of the OpuAR Repressor. Front Microbiol 2018; 9:2536. [PMID: 30405586 PMCID: PMC6207618 DOI: 10.3389/fmicb.2018.02536] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2018] [Accepted: 10/04/2018] [Indexed: 11/13/2022] Open
Abstract
Accumulation of compatible solutes is a common stress response of microorganisms challenged by high osmolarity; it can be achieved either through synthesis or import. These processes have been intensively studied in Bacillus subtilis, where systems for the production of the compatible solutes proline and glycine betaine have been identified, and in which five transporters for osmostress protectants (Opu) have been characterized. Glycine betaine synthesis relies on the import of choline via the substrate-restricted OpuB system and the promiscuous OpuC transporter and its subsequent oxidation by the GbsAB enzymes. Transcription of the opuB and gbsAB operons is under control of the MarR-type regulator GbsR, which acts as an intracellular choline-responsive repressor. Modeling studies using the X-ray structure of the Mj223 protein from Methanocaldococcus jannaschii as the template suggest that GbsR is a homo-dimer with an N-terminal DNA-reading head and C-terminal dimerization domain; a flexible linker connects these two domains. In the vicinity of the linker region, an aromatic cage is predicted as the inducer-binding site, whose envisioned architecture resembles that present in choline and glycine betaine substrate-binding proteins of ABC transporters. We used bioinformatics to assess the phylogenomics of GbsR-type proteins and found that they are widely distributed among Bacteria and Archaea. Alignments of GbsR proteins and analysis of the genetic context of the corresponding structural genes allowed their assignment into four sub-groups. In one of these sub-groups of GbsR-type proteins, gbsR-type genes are associated either with OpuA-, OpuB-, or OpuC-type osmostress protectants uptake systems. We focus here on GbsR-type proteins, named OpuAR by us, that control the expression of opuA-type gene clusters. Using such a system from the marine bacterium Bacillus infantis, we show that OpuAR acts as a repressor of opuA transcription, where several compatible solutes (e.g., choline, glycine betaine, proline betaine) serve as its inducers. Site-directed mutagenesis studies allowed a rational improvement of the putative inducer-binding site in OpuAR with respect to the affinity of choline and glycine betaine binding. Collectively, our data characterize GbsR-/OpuAR-type proteins as an extended sub-group within the MarR-superfamily of transcriptional regulators and identify a novel type of substrate-inducible import system for osmostress protectants.
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Affiliation(s)
- Stefanie Ronzheimer
- Laboratory for Microbiology, Department of Biology, Philipps-Universität Marburg, Marburg, Germany
| | - Bianca Warmbold
- Laboratory for Microbiology, Department of Biology, Philipps-Universität Marburg, Marburg, Germany
| | - Christian Arnhold
- Laboratory for Microbiology, Department of Biology, Philipps-Universität Marburg, Marburg, Germany
| | - Erhard Bremer
- Laboratory for Microbiology, Department of Biology, Philipps-Universität Marburg, Marburg, Germany.,LOEWE Center for Synthetic Microbiology, Philipps-Universität Marburg, Marburg, Germany
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Insight into the Genome of Staphylococcus xylosus, a Ubiquitous Species Well Adapted to Meat Products. Microorganisms 2017; 5:microorganisms5030052. [PMID: 28850086 PMCID: PMC5620643 DOI: 10.3390/microorganisms5030052] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2017] [Revised: 08/21/2017] [Accepted: 08/25/2017] [Indexed: 01/23/2023] Open
Abstract
Staphylococcus xylosus belongs to the vast group of coagulase-negative staphylococci. It is frequently isolated from meat products, either fermented or salted and dried, and is commonly used as starter cultures in sausage manufacturing. Analysis of the S. xylosus genome together with expression in situ in a meat model revealed that this bacterium is well adapted to meat substrates, being able to use diverse substrates as sources of carbon and energy and different sources of nitrogen. It is well-equipped with genes involved in osmotic, oxidative/nitrosative, and acidic stress responses. It is responsible for the development of the typical colour of cured meat products via its nitrate reductase activity. It contributes to sensorial properties, mainly by the the catabolism of pyruvate and amino acids resulting in odorous compounds and by the limiting of the oxidation of fatty acids, thereby avoiding rancidity.
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Vermassen A, Dordet-Frisoni E, de La Foye A, Micheau P, Laroute V, Leroy S, Talon R. Adaptation of Staphylococcus xylosus to Nutrients and Osmotic Stress in a Salted Meat Model. Front Microbiol 2016; 7:87. [PMID: 26903967 PMCID: PMC4742526 DOI: 10.3389/fmicb.2016.00087] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2015] [Accepted: 01/18/2016] [Indexed: 11/17/2022] Open
Abstract
Staphylococcus xylosus is commonly used as starter culture for meat fermentation. Its technological properties are mainly characterized in vitro, but the molecular mechanisms for its adaptation to meat remain unknown. A global transcriptomic approach was used to determine these mechanisms. S. xylosus modulated the expression of about 40-50% of the total genes during its growth and survival in the meat model. The expression of many genes involved in DNA machinery and cell division, but also in cell lysis, was up-regulated. Considering that the S. xylosus population remained almost stable between 24 and 72 h of incubation, our results suggest a balance between cell division and cell lysis in the meat model. The expression of many genes encoding enzymes involved in glucose and lactate catabolism was up-regulated and revealed that glucose and lactate were used simultaneously. S. xylosus seemed to adapt to anaerobic conditions as revealed by the overexpression of two regulatory systems and several genes encoding cofactors required for respiration. In parallel, genes encoding transport of peptides and peptidases that could furnish amino acids were up-regulated and thus concomitantly a lot of genes involved in amino acid synthesis were down-regulated. Several genes involved in glutamate homeostasis were up-regulated. Finally, S. xylosus responded to the osmotic stress generated by salt added to the meat model by overexpressing genes involved in transport and synthesis of osmoprotectants, and Na(+) and H(+) extrusion.
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Affiliation(s)
| | | | - Anne de La Foye
- INRA, Plateforme d'Exploration du MétabolismeSaint-Genès Champanelle, France
| | - Pierre Micheau
- INRA, UR454 MicrobiologieSaint-Genès Champanelle, France
| | - Valérie Laroute
- Université de Toulouse, INSA, UPS, INP, LISBPToulouse, France
| | - Sabine Leroy
- INRA, UR454 MicrobiologieSaint-Genès Champanelle, France
| | - Régine Talon
- INRA, UR454 MicrobiologieSaint-Genès Champanelle, France
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Muñoz-Clares RA, González-Segura L, Riveros-Rosas H, Julián-Sánchez A. Amino acid residues that affect the basicity of the catalytic glutamate of the hydrolytic aldehyde dehydrogenases. Chem Biol Interact 2015; 234:45-58. [DOI: 10.1016/j.cbi.2015.01.019] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2014] [Revised: 12/21/2014] [Accepted: 01/15/2015] [Indexed: 11/26/2022]
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Halavaty AS, Rich RL, Chen C, Joo JC, Minasov G, Dubrovska I, Winsor JR, Myszka DG, Duban M, Shuvalova L, Yakunin AF, Anderson WF. Structural and functional analysis of betaine aldehyde dehydrogenase from Staphylococcus aureus. ACTA CRYSTALLOGRAPHICA. SECTION D, BIOLOGICAL CRYSTALLOGRAPHY 2015; 71:1159-75. [PMID: 25945581 PMCID: PMC4427200 DOI: 10.1107/s1399004715004228] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/10/2014] [Accepted: 03/01/2015] [Indexed: 02/02/2023]
Abstract
When exposed to high osmolarity, methicillin-resistant Staphylococcus aureus (MRSA) restores its growth and establishes a new steady state by accumulating the osmoprotectant metabolite betaine. Effective osmoregulation has also been implicated in the acquirement of a profound antibiotic resistance by MRSA. Betaine can be obtained from the bacterial habitat or produced intracellularly from choline via the toxic betaine aldehyde (BA) employing the choline dehydrogenase and betaine aldehyde dehydrogenase (BADH) enzymes. Here, it is shown that the putative betaine aldehyde dehydrogenase SACOL2628 from the early MRSA isolate COL (SaBADH) utilizes betaine aldehyde as the primary substrate and nicotinamide adenine dinucleotide (NAD(+)) as the cofactor. Surface plasmon resonance experiments revealed that the affinity of NAD(+), NADH and BA for SaBADH is affected by temperature, pH and buffer composition. Five crystal structures of the wild type and three structures of the Gly234Ser mutant of SaBADH in the apo and holo forms provide details of the molecular mechanisms of activity and substrate specificity/inhibition of this enzyme.
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Affiliation(s)
- Andrei S. Halavaty
- Department of Biochemistry and Molecular Genetics, Northwestern University, 303 East Chicago Avenue, Chicago, IL 60611, USA
- Center for Structural Genomics of Infectious Diseases (CSGID), Chicago, IL 60611, USA
| | | | - Chao Chen
- Department of Chemical Engineering and Applied Chemistry, University of Toronto, 200 College Street, Toronto, Ontario M5S 3E5, Canada
| | - Jeong Chan Joo
- Department of Chemical Engineering and Applied Chemistry, University of Toronto, 200 College Street, Toronto, Ontario M5S 3E5, Canada
| | - George Minasov
- Department of Biochemistry and Molecular Genetics, Northwestern University, 303 East Chicago Avenue, Chicago, IL 60611, USA
- Center for Structural Genomics of Infectious Diseases (CSGID), Chicago, IL 60611, USA
| | - Ievgeniia Dubrovska
- Department of Biochemistry and Molecular Genetics, Northwestern University, 303 East Chicago Avenue, Chicago, IL 60611, USA
- Center for Structural Genomics of Infectious Diseases (CSGID), Chicago, IL 60611, USA
| | - James R. Winsor
- Department of Biochemistry and Molecular Genetics, Northwestern University, 303 East Chicago Avenue, Chicago, IL 60611, USA
- Center for Structural Genomics of Infectious Diseases (CSGID), Chicago, IL 60611, USA
| | | | - Mark Duban
- Center for Structural Genomics of Infectious Diseases (CSGID), Chicago, IL 60611, USA
| | - Ludmilla Shuvalova
- Department of Biochemistry and Molecular Genetics, Northwestern University, 303 East Chicago Avenue, Chicago, IL 60611, USA
- Center for Structural Genomics of Infectious Diseases (CSGID), Chicago, IL 60611, USA
| | - Alexander F. Yakunin
- Department of Chemical Engineering and Applied Chemistry, University of Toronto, 200 College Street, Toronto, Ontario M5S 3E5, Canada
| | - Wayne F. Anderson
- Department of Biochemistry and Molecular Genetics, Northwestern University, 303 East Chicago Avenue, Chicago, IL 60611, USA
- Center for Structural Genomics of Infectious Diseases (CSGID), Chicago, IL 60611, USA
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12
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Bashir A, Hoffmann T, Smits SHJ, Bremer E. Dimethylglycine provides salt and temperature stress protection to Bacillus subtilis. Appl Environ Microbiol 2014; 80:2773-85. [PMID: 24561588 PMCID: PMC3993278 DOI: 10.1128/aem.00078-14] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2014] [Accepted: 02/17/2014] [Indexed: 12/13/2022] Open
Abstract
Glycine betaine is a potent osmotic and thermal stress protectant of many microorganisms. Its synthesis from glycine results in the formation of the intermediates monomethylglycine (sarcosine) and dimethylglycine (DMG), and these compounds are also produced when it is catabolized. Bacillus subtilis does not produce sarcosine or DMG, and it cannot metabolize these compounds. Here we have studied the potential of sarcosine and DMG to protect B. subtilis against osmotic, heat, and cold stress. Sarcosine, a compatible solute that possesses considerable protein-stabilizing properties, did not serve as a stress protectant of B. subtilis. DMG, on the other hand, proved to be only moderately effective as an osmotic stress protectant, but it exhibited good heat stress-relieving and excellent cold stress-relieving properties. DMG is imported into B. subtilis cells primarily under osmotic and temperature stress conditions via OpuA, a member of the ABC family of transporters. Ligand-binding studies with the extracellular solute receptor (OpuAC) of the OpuA system showed that OpuAC possesses a moderate affinity for DMG, with a Kd value of approximate 172 μM; its Kd for glycine betaine is about 26 μM. Docking studies using the crystal structures of the OpuAC protein with the sulfur analog of DMG, dimethylsulfonioacetate, as a template suggest a model of how the DMG molecule can be stably accommodated within the aromatic cage of the OpuAC ligand-binding pocket. Collectively, our data show that the ability to acquire DMG from exogenous sources under stressful environmental conditions helps the B. subtilis cell to cope with growth-restricting osmotic and temperature challenges.
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Affiliation(s)
- Abdallah Bashir
- Laboratory for Microbiology, Department of Biology, Philipps-Universität Marburg, Marburg, Germany
- Al-Azhar University—Gaza, Faculty of Science, Biology Department, Gaza
- Max Planck Institute for Terrestrial Microbiology, Emeritus Group of R. K. Thauer, Marburg, Germany
| | - Tamara Hoffmann
- Laboratory for Microbiology, Department of Biology, Philipps-Universität Marburg, Marburg, Germany
- LOEWE Center for Synthetic Microbiology, Philipps-Universität Marburg, Marburg, Germany
| | - Sander H. J. Smits
- Institute of Biochemistry, Heinrich Heine University Düsseldorf, Düsseldorf, Germany
| | - Erhard Bremer
- Laboratory for Microbiology, Department of Biology, Philipps-Universität Marburg, Marburg, Germany
- LOEWE Center for Synthetic Microbiology, Philipps-Universität Marburg, Marburg, Germany
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13
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Rubiano-Labrador C, Bland C, Miotello G, Guérin P, Pible O, Baena S, Armengaud J. Proteogenomic insights into salt tolerance by a halotolerant alpha-proteobacterium isolated from an Andean saline spring. J Proteomics 2013; 97:36-47. [PMID: 23727365 DOI: 10.1016/j.jprot.2013.05.020] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2012] [Revised: 04/30/2013] [Accepted: 05/16/2013] [Indexed: 01/18/2023]
Abstract
UNLABELLED Tistlia consotensis is a halotolerant Rhodospirillaceae that was isolated from a saline spring located in the Colombian Andes with a salt concentration close to seawater (4.5%w/vol). We cultivated this microorganism in three NaCl concentrations, i.e. optimal (0.5%), without (0.0%) and high (4.0%) salt concentration, and analyzed its cellular proteome. For assigning tandem mass spectrometry data, we first sequenced its genome and constructed a six reading frame ORF database from the draft sequence. We annotated only the genes whose products (872) were detected. We compared the quantitative proteome data sets recorded for the three different growth conditions. At low salinity general stress proteins (chaperons, proteases and proteins associated with oxidative stress protection), were detected in higher amounts, probably linked to difficulties for proper protein folding and metabolism. Proteogenomics and comparative genomics pointed at the CrgA transcriptional regulator as a key-factor for the proteome remodeling upon low osmolarity. In hyper-osmotic condition, T. consotensis produced in larger amounts proteins involved in the sensing of changes in salt concentration, as well as a wide panel of transport systems for the transport of organic compatible solutes such as glutamate. We have described here a straightforward procedure in making a new environmental isolate quickly amenable to proteomics. BIOLOGICAL SIGNIFICANCE The bacterium Tistlia consotensis was isolated from a saline spring in the Colombian Andes and represents an interesting environmental model to be compared with extremophiles or other moderate organisms. To explore the halotolerance molecular mechanisms of the bacterium T. consotensis, we developed an innovative proteogenomic strategy consisting of i) genome sequencing, ii) quick annotation of the genes whose products were detected by mass spectrometry, and iii) comparative proteomics of cells grown in three salt conditions. We highlighted in this manuscript how efficient such an approach can be compared to time-consuming genome annotation when pointing at the key proteins of a given biological question. We documented a large number of proteins found produced in greater amounts when cells are cultivated in either hypo-osmotic or hyper-osmotic conditions. This article is part of a Special Issue entitled: Trends in Microbial Proteomics.
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Affiliation(s)
- Carolina Rubiano-Labrador
- Unidad de Saneamiento y Biotecnología Ambiental, Departamento de Biología, Pontificia Universidad Javeriana, POB 56710, Bogotá D.C., Colombia; Colombian Center for Genomics and Bioinformatics of Extreme Environments, GeBiX, Colombia
| | - Céline Bland
- CEA, DSV, iBEB, SBTN, Lab Biochim System Perturb, Bagnols-sur-Cèze, F-30207, France
| | - Guylaine Miotello
- CEA, DSV, iBEB, SBTN, Lab Biochim System Perturb, Bagnols-sur-Cèze, F-30207, France
| | - Philippe Guérin
- CEA, DSV, iBEB, SBTN, Lab Biochim System Perturb, Bagnols-sur-Cèze, F-30207, France
| | - Olivier Pible
- CEA, DSV, iBEB, SBTN, Lab Biochim System Perturb, Bagnols-sur-Cèze, F-30207, France
| | - Sandra Baena
- Unidad de Saneamiento y Biotecnología Ambiental, Departamento de Biología, Pontificia Universidad Javeriana, POB 56710, Bogotá D.C., Colombia; Colombian Center for Genomics and Bioinformatics of Extreme Environments, GeBiX, Colombia
| | - Jean Armengaud
- CEA, DSV, iBEB, SBTN, Lab Biochim System Perturb, Bagnols-sur-Cèze, F-30207, France.
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14
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González-Segura L, Riveros-Rosas H, Díaz-Sánchez AG, Julián-Sánchez A, Muñoz-Clares RA. Potential monovalent cation-binding sites in aldehyde dehydrogenases. Chem Biol Interact 2013; 202:41-50. [PMID: 23295228 DOI: 10.1016/j.cbi.2012.12.007] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2012] [Revised: 12/12/2012] [Accepted: 12/18/2012] [Indexed: 10/27/2022]
Abstract
Potassium ions are non-essential activators of several aldehyde dehydrogenases (ALDHs), whereas a few others require the cation for activity. Two kinds of cation-binding sites, which we named intra-subunit and inter-subunit, have been observed in crystal structures of ALDHs, and based on reported crystallographic data, we here propose the existence of a third kind located in the central cavity of some tetrameric ALDHs. Given the high structural similarity between these enzymes, cation-binding sites may be present in many other members of this superfamily. To explore the prevalence of these sites, we compared 37 known crystal structures from 13 different ALDH families and evaluated the possible existence of a cation on the basis of the number, distance and geometry of its potential interactions, as well as of B-factor values of modeled cations obtained in new refinements of some reported crystal structures. Also, by performing multiple alignments of 855 non-redundant amino acid sequences, we assessed the degree of conservation in their respective families of the amino acid residues putatively relevant for cation binding. Among the ALDH enzymes studied, and according to our analyses, potential intra-subunit cation-binding sites seem to be present in most members of ALDH2, ALDH1L, ALDH4, ALDH5, ALDH7, ALDH10, and ALDH25 families, as well as in the bacterial and fungal members of the ALDH9 family and in a few ALDH1, ALDH6, ALDH11 and ALDH26 enzymes; potential inter-subunit sites in members of ALDH1L, ALDH3, ALDH4 from bacillales, ALDH5, ALDH7, ALDH9, ALDH10, ALDH11 and ALDH25 families; and potential central-cavity sites only in some bacterial and animal ALDH9s and in most members of the ALDH1L family. Because potassium is the most abundant intracellular cation, we propose that these are potassium-binding sites, but the specific structural and/or functional roles of the cation bound to these different sites remain to be investigated.
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Affiliation(s)
- Lilian González-Segura
- Departamento de Bioquímica, Facultad de Química, Universidad Nacional Autónoma de México, México, DF 04510, Mexico
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15
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Riveros-Rosas H, González-Segura L, Julián-Sánchez A, Díaz-Sánchez AG, Muñoz-Clares RA. Structural determinants of substrate specificity in aldehyde dehydrogenases. Chem Biol Interact 2012; 202:51-61. [PMID: 23219887 DOI: 10.1016/j.cbi.2012.11.015] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2012] [Revised: 11/24/2012] [Accepted: 11/27/2012] [Indexed: 12/28/2022]
Abstract
Within the aldehyde dehydrogenase (ALDH) superfamily, proteins belonging to the ALDH9, ALDH10, ALDH25, ALDH26 and ALDH27 families display activity as ω-aminoaldehyde dehydrogenases (AMADHs). These enzymes participate in polyamine, choline and arginine catabolism, as well as in synthesis of several osmoprotectants and carnitine. Active site aromatic and acidic residues are involved in binding the ω-aminoaldehydes in plant ALDH10 enzymes. In order to ascertain the degree of conservation of these residues among AMADHs and to evaluate their possible relevance in determining the aminoaldehyde specificity, we compared the known amino acid sequences of every ALDH family that have at least one member with known crystal structure, as well as the electrostatic potential surface of the aldehyde binding sites of these structures. Our analyses showed that four or three aromatic residues form a similar "aromatic box" in the active site of the AMADH enzymes, being the equivalents to Phe170 and Trp177 (human ALDH2 numbering) strictly conserved in all of them, which supports their relevance in binding the aminoaldehyde by cation-π interactions. In addition, all AMADHs exhibit a negative electrostatic potential surface in the aldehyde-entrance tunnel, due to side-chain carboxyl and hydroxyl groups or main-chain carbonyl groups. In contrast, ALDHs that have non-polar or negatively charged substrates exhibit neutral or positive electrostatic potential surfaces, respectively. Finally, our comparative sequence analyses revealed that the residues equivalent to Asp121 and Phe170 are highly conserved in many ALDH families irrespective of their substrate specificity-suggesting that they perform a role in catalysis additional or different to binding of the substrate-and that the positions Met124, Cys301, and Cys303 are hot spots changed during evolution to confer aldehyde specificity to several ALDH families.
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Affiliation(s)
- Héctor Riveros-Rosas
- Departamento de Bioquímica, Facultad de Medicina, Universidad Nacional Autónoma de México, 04510 México, DF, Mexico
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16
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Nau-Wagner G, Opper D, Rolbetzki A, Boch J, Kempf B, Hoffmann T, Bremer E. Genetic control of osmoadaptive glycine betaine synthesis in Bacillus subtilis through the choline-sensing and glycine betaine-responsive GbsR repressor. J Bacteriol 2012; 194:2703-14. [PMID: 22408163 PMCID: PMC3347207 DOI: 10.1128/jb.06642-11] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2011] [Accepted: 02/27/2012] [Indexed: 11/20/2022] Open
Abstract
Synthesis of the compatible solute glycine betaine confers a considerable degree of osmotic stress tolerance to Bacillus subtilis. This osmoprotectant is produced through the uptake of the precursor choline via the osmotically inducible OpuB and OpuC ABC transporters and a subsequent two-step oxidation process by the GbsB and GbsA enzymes. We characterized a regulatory protein, GbsR, controlling the transcription of both the structural genes for the glycine betaine biosynthetic enzymes (gbsAB) and those for the choline-specific OpuB transporter (opuB) but not of that for the promiscuous OpuC transporter. GbsR acts genetically as a repressor and functions as an intracellular choline sensor. Spectroscopic analysis of the purified GbsR protein showed that it binds the inducer choline with an apparent K(D) (equilibrium dissociation constant) of approximately 165 μM. Based on the X-ray structure of a protein (Mj223) from Methanococcus jannaschii, a homology model for GbsR was derived. Inspection of this GbsR in silico model revealed a possible ligand-binding pocket for choline resembling those of known choline-binding sites present in solute receptors of microbial ABC transporters, e.g., that of the OpuBC ligand-binding protein of the OpuB ABC transporter. GbsR was not only needed to control gbsAB and opuB expression in response to choline availability but also required to genetically tune down glycine betaine production once cellular adjustment to high osmolarity has been achieved. The GbsR regulatory protein from B. subtilis thus records and integrates cellular and environmental signals for both the onset and the repression of the synthesis of the osmoprotectant glycine betaine.
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Affiliation(s)
- Gabriele Nau-Wagner
- Philipps-University Marburg, Department of Biology, Laboratory for Microbiology, Marburg, Germany
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17
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Pittelkow M, Tschapek B, Smits SHJ, Schmitt L, Bremer E. The crystal structure of the substrate-binding protein OpuBC from Bacillus subtilis in complex with choline. J Mol Biol 2011; 411:53-67. [PMID: 21658392 DOI: 10.1016/j.jmb.2011.05.037] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2011] [Revised: 05/17/2011] [Accepted: 05/24/2011] [Indexed: 11/20/2022]
Abstract
Bacillus subtilis can synthesize the compatible solute glycine betaine as an osmoprotectant from an exogenous supply of the precursor choline. Import of choline is mediated by two osmotically inducible ABC transport systems: OpuB and OpuC. OpuC catalyzes the import of various osmoprotectants, whereas OpuB is highly specific for choline. OpuBC is the substrate-binding protein of the OpuB transporter, and we have analyzed the affinity of the OpuBC/choline complex by intrinsic tryptophan fluorescence and determined a K(d) value of about 30 μM. The X-ray crystal structure of the OpuBC/choline complex was solved at a resolution of 1.6 Å and revealed a fold typical of class II substrate-binding proteins. The positively charged trimethylammonium head group of choline is wedged into an aromatic cage formed by four tyrosine residues and is bound via cation-pi interactions. The hydroxyl group of choline protrudes out of this aromatic cage and makes a single interaction with residue Gln19. The substitution of this residue by Ala decreases choline binding affinity by approximately 15-fold. A water network stabilizes choline within its substrate-binding site and promotes indirect interactions between the two lobes of the OpuBC protein. Disruption of this intricate water network by site-directed mutagenesis of selected residues in OpuBC either strongly reduces choline binding affinity (between 18-fold and 25-fold) or abrogates ligand binding. The crystal structure of the OpuBC/choline complex provides a rational for the observed choline specificity of the OpuB ABC importer in vivo and explains its inability to catalyze the import of glycine betaine into osmotically stressed B. subtilis cells.
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Affiliation(s)
- Marco Pittelkow
- Laboratory for Microbiology, Department of Biology, Philipps University Marburg, Marburg, Germany
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18
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Ziegler C, Bremer E, Krämer R. The BCCT family of carriers: from physiology to crystal structure. Mol Microbiol 2011; 78:13-34. [PMID: 20923416 DOI: 10.1111/j.1365-2958.2010.07332.x] [Citation(s) in RCA: 86] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Increases in the environmental osmolarity are key determinants for the growth of microorganisms. To ensure a physiologically acceptable level of cellular hydration and turgor at high osmolarity, many bacteria accumulate compatible solutes. Osmotically controlled uptake systems allow the scavenging of these compounds from scarce environmental sources as effective osmoprotectants. A number of these systems belong to the BCCT family (betaine-choline-carnitine-transporter), sodium- or proton-coupled transporters (e.g. BetP and BetT respectively) that are ubiquitous in microorganisms. The BCCT family also contains CaiT, an L-carnitine/γ-butyrobetaine antiporter that is not involved in osmotic stress responses. The glycine betaine transporter BetP from Corynebacterium glutamicum is a representative for osmoregulated symporters of the BCCT family and functions both as an osmosensor and osmoregulator. The crystal structure of BetP in an occluded conformation in complex with its substrate glycine betaine and two crystal structures of CaiT in an inward-facing open conformation in complex with L-carnitine and γ-butyrobetaine were reported recently. These structures and the wealth of biochemical data on the activity control of BetP in response to osmotic stress enable a correlation between the sensing of osmotic stress by a transporter protein with the ensuing regulation of transport activity. Molecular determinants governing the high-affinity binding of the compatible solutes by BetP and CaiT, the coupling in symporters and antiporters, and the osmoregulatory properties are discussed in detail for BetP and various BCCT carriers.
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Affiliation(s)
- Christine Ziegler
- Max-Planck Institute for Biophysics, Max-von-Laue Street 3, D-60438 Frankfurt, Germany
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19
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Burkhardt J, Sewald X, Bauer B, Saum SH, Müller V. Synthesis of glycine betaine from choline in the moderate halophile Halobacillus halophilus: co-regulation of two divergent, polycistronic operons. ENVIRONMENTAL MICROBIOLOGY REPORTS 2009; 1:38-43. [PMID: 23765718 DOI: 10.1111/j.1758-2229.2008.00001.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
The moderately halophilic bacterium Halobacillus halophilus can synthesize glycine betaine from choline. Oxidation of choline is induced by salinity and repressed by exogenous glycine betaine. The genes encoding the choline dehydrogenase (gbsB) and the glycine betaine aldehyde dehydrogenase (gbsA) were identified and shown to constitute an operon. Divergent to this operon is another operon containing gbsR and gbsU that encode proteins with similarities to a transcriptional regulator and a glycine betaine-binding protein respectively. Synthesis of the four Gbs proteins was strictly dependent on the choline concentration of the medium. Salinity was essential for the production of GbsB and increased the production of GbsA, GbsR and GbsU. Glycine betaine repressed the production of all four Gbs proteins with half maximal inhibition at 0.1 mM glycine betaine.
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Affiliation(s)
- Janin Burkhardt
- Molecular Microbiology & Bioenergetics, Institute of Molecular Biosciences, Goethe University, Frankfurt am Main, Germany
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20
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Gu ZJ, Wang L, Le Rudulier D, Zhang B, Yang SS. Characterization of the Glycine Betaine Biosynthetic Genes in the Moderately Halophilic Bacterium Halobacillus dabanensis D-8T. Curr Microbiol 2008; 57:306-11. [DOI: 10.1007/s00284-008-9194-9] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2008] [Accepted: 04/25/2008] [Indexed: 10/21/2022]
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21
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Chen C, Beattie GA. Pseudomonas syringae BetT is a low-affinity choline transporter that is responsible for superior osmoprotection by choline over glycine betaine. J Bacteriol 2008; 190:2717-25. [PMID: 18156257 PMCID: PMC2293270 DOI: 10.1128/jb.01585-07] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2007] [Accepted: 12/12/2007] [Indexed: 11/20/2022] Open
Abstract
The plant pathogen Pseudomonas syringae derives better osmoprotection from choline than from glycine betaine, unlike most bacteria that have been characterized. In this report, we identified a betaine/carnitine/choline family transporter (BCCT) in P. syringae pv. tomato strain DC3000 that mediates the transport of choline and acetylcholine. This transporter has a particularly low affinity (K(m) of 876 microM) and high capacity (V(max) of 80 nmol/min/mg of protein) for choline transport relative to other known BCCTs. Although BetT activity increased in response to hyperosmolarity, BetT mediated significant uptake under low-osmolarity conditions, suggesting a role in transport for both osmoprotection and catabolism. Growth studies with mutants deficient in BetT and other choline transporters demonstrated that BetT was responsible for the superior osmoprotection conferred to P. syringae by choline over glycine betaine when these compounds were provided at high concentrations (>100 microM). These results suggest that P. syringae has evolved to survive in relatively choline-rich habitats, a prediction that is supported by the common association of P. syringae with plants and the widespread production of choline, but genus- and species-specific production of glycine betaine, by plants. Among the three putative BCCT family transporters in Pseudomonas aeruginosa and six in Pseudomonas putida, different transporters were predicted to function based on similarity to Escherichia coli BetT than to P. syringae BetT. Functional P. putida and P. aeruginosa transporters were identified, and their possession of a long C-terminal tail suggested an osmoregulatory function for this tail; this function was confirmed for P. syringae BetT using deletion derivatives.
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Affiliation(s)
- Chiliang Chen
- Iowa State University, Department of Plant Pathology, 207 Science I, Ames, IA 50011-3211, USA
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22
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Rediers H, Rainey PB, Vanderleyden J, De Mot R. Unraveling the secret lives of bacteria: use of in vivo expression technology and differential fluorescence induction promoter traps as tools for exploring niche-specific gene expression. Microbiol Mol Biol Rev 2005; 69:217-61. [PMID: 15944455 PMCID: PMC1197422 DOI: 10.1128/mmbr.69.2.217-261.2005] [Citation(s) in RCA: 119] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
A major challenge for microbiologists is to elucidate the strategies deployed by microorganisms to adapt to and thrive in highly complex and dynamic environments. In vitro studies, including those monitoring genomewide changes, have proven their value, but they can, at best, mimic only a subset of the ensemble of abiotic and biotic stimuli that microorganisms experience in their natural habitats. The widely used gene-to-phenotype approach involves the identification of altered niche-related phenotypes on the basis of gene inactivation. However, many traits contributing to ecological performance that, upon inactivation, result in only subtle or difficult to score phenotypic changes are likely to be overlooked by this otherwise powerful approach. Based on the premise that many, if not most, of the corresponding genes will be induced or upregulated in the environment under study, ecologically significant genes can alternatively be traced using the promoter trap techniques differential fluorescence induction and in vivo expression technology (IVET). The potential and limitations are discussed for the different IVET selection strategies and system-specific variants thereof. Based on a compendium of genes that have emerged from these promoter-trapping studies, several functional groups have been distinguished, and their physiological relevance is illustrated with follow-up studies of selected genes. In addition to confirming results from largely complementary approaches such as signature-tagged mutagenesis, some unexpected parallels as well as distinguishing features of microbial phenotypic acclimation in diverse environmental niches have surfaced. On the other hand, by the identification of a large proportion of genes with unknown function, these promoter-trapping studies underscore how little we know about the secret lives of bacteria and other microorganisms.
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Affiliation(s)
- Hans Rediers
- Centre of Microbial and Plant Genetics, Heverlee, Belgium
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23
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Cánovas D, Vargas C, Kneip S, Morón MAJ, Ventosa A, Bremer E, Nieto JNJ. Genes for the synthesis of the osmoprotectant glycine betaine from choline in the moderately halophilic bacterium Halomonas elongata DSM 3043, USA. MICROBIOLOGY (READING, ENGLAND) 2000; 146 ( Pt 2):455-463. [PMID: 10708384 DOI: 10.1099/00221287-146-2-455] [Citation(s) in RCA: 67] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The genes involved in the oxidative pathway of choline to glycine betaine in the moderate halophile Halomonas elongata DSM 3043 were isolated by functional complementation of an Escherichia coli strain defective in glycine betaine synthesis. The cloned region was able to mediate the oxidation of choline to glycine betaine in E. coli, but not the transport of choline, indicating that the gene(s) involved in choline transport are not clustered with the glycine betaine synthesis genes. Nucleotide sequence analysis of a 4.6 kb segment from the cloned DNA revealed the occurrence of three ORFs (betIBA) apparently arranged in an operon. The deduced betI gene product exhibited features typical for DNA-binding regulatory proteins. The deduced BetB and BetA proteins showed significant similarity to soluble glycine betaine aldehyde dehydrogenases and membrane-bound choline dehydrogenases, respectively, from a variety of organisms. Evidence is presented that BetA is able to oxidize both choline and glycine betaine aldehyde and therefore can mediate both steps in the synthesis of glycine betaine.
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Affiliation(s)
- David Cánovas
- Laboratory for Microbiology, Department of Biology, Philipps University, MarburgD-35032, Marburg, Germany2
- Department of Microbiology and Parasitology, Faculty of Pharmacy, University of Seville, 41012 Seville, Spain1
| | - Carmen Vargas
- Department of Microbiology and Parasitology, Faculty of Pharmacy, University of Seville, 41012 Seville, Spain1
| | - Susanne Kneip
- Laboratory for Microbiology, Department of Biology, Philipps University, MarburgD-35032, Marburg, Germany2
| | - Marı A-Jesús Morón
- Department of Microbiology and Parasitology, Faculty of Pharmacy, University of Seville, 41012 Seville, Spain1
| | - Antonio Ventosa
- Department of Microbiology and Parasitology, Faculty of Pharmacy, University of Seville, 41012 Seville, Spain1
| | - Erhard Bremer
- Laboratory for Microbiology, Department of Biology, Philipps University, MarburgD-35032, Marburg, Germany2
| | - Joaquı N J Nieto
- Department of Microbiology and Parasitology, Faculty of Pharmacy, University of Seville, 41012 Seville, Spain1
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