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Berger TM, Michaelis C, Probst I, Sagmeister T, Petrowitsch L, Puchner S, Pavkov-Keller T, Gesslbauer B, Grohmann E, Keller W. Small Things Matter: The 11.6-kDa TraB Protein is Crucial for Antibiotic Resistance Transfer Among Enterococci. Front Mol Biosci 2022; 9:867136. [PMID: 35547396 PMCID: PMC9083827 DOI: 10.3389/fmolb.2022.867136] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2022] [Accepted: 03/14/2022] [Indexed: 11/18/2022] Open
Abstract
Conjugative transfer is the most important means for spreading antibiotic resistance genes. It is used by Gram-positive and Gram-negative bacteria, and archaea as well. Conjugative transfer is mediated by molecular membrane-spanning nanomachines, so called Type 4 Secretion Systems (T4SS). The T4SS of the broad-host-range inc18-plasmid pIP501 is organized in a single operon encoding 15 putative transfer proteins. pIP501 was originally isolated from a clinical Streptococcus agalactiae strain but is mainly found in Enterococci. In this study, we demonstrate that the small transmembrane protein TraB is essential for pIP501 transfer. Complementation of a markerless pIP501∆traB knockout by traB lacking its secretion signal sequence did not fully restore conjugative transfer. Pull-downs with Strep-tagged TraB demonstrated interactions of TraB with the putative mating pair formation proteins, TraF, TraH, TraK, TraM, and with the lytic transglycosylase TraG. As TraB is the only putative mating pair formation complex protein containing a secretion signal sequence, we speculate on its role as T4SS recruitment factor. Moreover, structural features of TraB and TraB orthologs are presented, making an essential role of TraB-like proteins in antibiotic resistance transfer among Firmicutes likely.
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Affiliation(s)
- Tamara M.I. Berger
- Institute of Molecular Biosciences, Department of Structural Biology, University of Graz, Graz, Austria
| | - Claudia Michaelis
- Faculty of Life Sciences and Technology, Department of Microbiology, Berliner Hochschule für Technik, Berlin, Germany
| | - Ines Probst
- Division of Infectious Diseases, University Medical Center Freiburg, Freiburg, Germany
| | - Theo Sagmeister
- Institute of Molecular Biosciences, Department of Structural Biology, University of Graz, Graz, Austria
| | - Lukas Petrowitsch
- Institute of Molecular Biosciences, Department of Structural Biology, University of Graz, Graz, Austria
| | - Sandra Puchner
- Faculty of Life Sciences and Technology, Department of Microbiology, Berliner Hochschule für Technik, Berlin, Germany
| | - Tea Pavkov-Keller
- Institute of Molecular Biosciences, Department of Structural Biology, University of Graz, Graz, Austria
- Field of Excellence BioHealth, University of Graz, Graz, Austria
- BioTechMed-Graz, Graz, Austria
| | - Bernd Gesslbauer
- Institute of Pharmaceutical Sciences, Division of Pharmaceutical Chemistry, University of Graz, Graz, Austria
| | - Elisabeth Grohmann
- Faculty of Life Sciences and Technology, Department of Microbiology, Berliner Hochschule für Technik, Berlin, Germany
| | - Walter Keller
- Institute of Molecular Biosciences, Department of Structural Biology, University of Graz, Graz, Austria
- Field of Excellence BioHealth, University of Graz, Graz, Austria
- BioTechMed-Graz, Graz, Austria
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2
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DdvK, a Novel Major Facilitator Superfamily Transporter Essential for 5,5'-Dehydrodivanillate Uptake by Sphingobium sp. Strain SYK-6. Appl Environ Microbiol 2018; 84:AEM.01314-18. [PMID: 30120118 DOI: 10.1128/aem.01314-18] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2018] [Accepted: 08/02/2018] [Indexed: 12/28/2022] Open
Abstract
The microbial conversion of lignin-derived aromatics is a promising strategy for the industrial utilization of this large biomass resource. However, efficient application requires an elucidation of the relevant transport and catabolic pathways. In Sphingobium sp. strain SYK-6, most of the enzyme genes involved in 5,5'-dehydrodivanillate (DDVA) catabolism have been characterized, but the transporter has not yet been identified. Here, we identified SLG_07710 (ddvK) and SLG_07780 (ddvR), genes encoding a putative major facilitator superfamily (MFS) transporter and MarR-type transcriptional regulator, respectively. A ddvK mutant of SYK-6 completely lost the capacity to grow on and convert DDVA. DdvR repressed the expression of the DDVA O-demethylase oxygenase component gene (ligXa), while DDVA acted as the gene inducer. A DDVA uptake assay was developed by employing this DdvR-controlled ligXa transcriptional regulatory system. A Sphingobium japonicum UT26S transformant expressing ddvK acquired DDVA uptake capacity, indicating that ddvK encodes the DDVA transporter. DdvK, probably requiring the proton motive force, was suggested to be a novel MFS transporter on the basis of the amino acid sequence similarity. Subsequently, we evaluated the effects of ddvK overexpression on the production of the DDVA metabolite 2-pyrone-4,6-dicarboxylate (PDC), a building block of functional polymers. A SYK-6 mutant of the PDC hydrolase gene (ligI) cultured in DDVA accumulated PDC via 5-carboxyvanillate and grew by utilizing 4-carboxy-2-hydroxypenta-2,4-dienoate. The introduction of a ddvK-expression plasmid into a ligI mutant increased the growth rate in DDVA and the amounts of DDVA converted and PDC produced after 48 h by 1.35- and 1.34-fold, respectively. These results indicate that enhanced transporter gene expression can improve metabolite production from lignin derivatives.IMPORTANCE The bioengineering of bacteria to selectively transport and metabolize natural substrates into specific metabolites is a valuable strategy for industrial-scale chemical production. The uptake of many substrates into cells requires specific transport systems, and so the identification and characterization of transporter genes are essential for industrial applications. A number of bacterial major facilitator superfamily transporters of aromatic acids have been identified and characterized, but many transporters of lignin-derived aromatic acids remain unidentified. The efficient conversion of lignin, an abundant but unutilized aromatic biomass resource, to value-added metabolites using microbial catabolism requires the characterization of transporters for lignin-derived aromatics. In this study, we identified the transporter gene responsible for the uptake of 5,5'-dehydrodivanillate, a lignin-derived biphenyl compound, in Sphingobium sp. strain SYK-6. In addition to characterizing its function, we applied this transporter gene to the production of a value-added metabolite from 5,5'-dehydrodivanillate.
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3
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Mori K, Kamimura N, Masai E. Identification of the protocatechuate transporter gene in Sphingobium sp. strain SYK-6 and effects of overexpression on production of a value-added metabolite. Appl Microbiol Biotechnol 2018; 102:4807-4816. [DOI: 10.1007/s00253-018-8988-3] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2018] [Revised: 03/22/2018] [Accepted: 04/05/2018] [Indexed: 11/28/2022]
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4
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Physiological and transcriptome changes induced by Pseudomonas putida acquisition of an integrative and conjugative element. Sci Rep 2018; 8:5550. [PMID: 29615803 PMCID: PMC5882942 DOI: 10.1038/s41598-018-23858-6] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2018] [Accepted: 03/21/2018] [Indexed: 12/27/2022] Open
Abstract
Integrative and conjugative elements (ICEs) comprise ubiquitous large mobile regions in prokaryotic chromosomes that transmit vertically to daughter cells and transfer horizontally to distantly related lineages. Their evolutionary success originates in maximized combined ICE-host fitness trade-offs, but how the ICE impacts on the host metabolism and physiology is poorly understood. Here we investigate global changes in the host genetic network and physiology of Pseudomonas putida with or without an integrated ICEclc, a model ICE widely distributed in proteobacterial genomes. Genome-wide gene expression differences were analyzed by RNA-seq using exponentially growing or stationary phase-restimulated cultures on 3-chlorobenzoate, an aromatic compound metabolizable thanks to specific ICEclc-located genes. We found that the presence of ICEclc imposes a variety of changes in global pathways such as cell cycle and amino acid metabolism, which were more numerous in stationary-restimulated than exponential phase cells. Unexpectedly, ICEclc stimulates cellular motility and leads to more rapid growth on 3-chlorobenzoate than cells carrying only the integrated clc genes. ICEclc also concomitantly activates the P. putida Pspu28-prophage, but this in itself did not provoke measurable fitness effects. ICEclc thus interferes in a number of cellular pathways, inducing both direct benefits as well as indirect costs in P. putida.
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5
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Hegedüs B, Kós PB, Bende G, Bounedjoum N, Maróti G, Laczi K, Szuhaj M, Perei K, Rákhely G. Starvation- and xenobiotic-related transcriptomic responses of the sulfanilic acid-degrading bacterium, Novosphingobium resinovorum SA1. Appl Microbiol Biotechnol 2017; 102:305-318. [PMID: 29051988 DOI: 10.1007/s00253-017-8553-5] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2017] [Revised: 09/19/2017] [Accepted: 09/26/2017] [Indexed: 10/18/2022]
Abstract
Novosphingobium resinovorum SA1 was the first single isolate capable of degrading sulfanilic acid, a widely used representative of sulfonated aromatic compounds. The genome of the strain was recently sequenced, and here, we present whole-cell transcriptome analyses of cells exposed to sulfanilic acid as compared to cells grown on glucose. The comparison of the transcript profiles suggested that the primary impact of sulfanilic acid on the cell transcriptome was a starvation-like effect. The genes of the peripheral, central, and common pathways of sulfanilic acid biodegradation had distinct transcript profiles. The peripheral genes located on a plasmid had very high basal expressions which were hardly upregulated by sulfanilic acid. The genomic context and the codon usage preference of these genes suggested that they were acquired by horizontal gene transfer. The genes of the central pathways were remarkably inducible by sulfanilic acid indicating the presence of a substrate-specific regulatory system in the cells. Surprisingly, the genes of the common part of the metabolic pathway had low and sulfanilic acid-independent transcript levels. The approach applied resulted in the identification of the genes of proteins involved in auxiliary processes such as electron transfer, substrate and iron transports, sulfite oxidases, and sulfite transporters. The whole transcriptome analysis revealed that the cells exposed to xenobiotics had multiple responses including general starvation-like, substrate-specific, and substrate-related effects. From the results, we propose that the genes of the peripheral, central, and common parts of the pathway have been evolved independently.
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Affiliation(s)
- Botond Hegedüs
- Department of Biotechnology, University of Szeged, Közép fasor 52, Szeged, 6726, Hungary.,Institute of Biophysics, Biological Research Center, Temesvári krt. 62, Szeged, 6726, Hungary
| | - Péter B Kós
- Department of Biotechnology, University of Szeged, Közép fasor 52, Szeged, 6726, Hungary.,Institute of Plant Biology, Biological Research Center, Temesvári krt. 62, Szeged, 6726, Hungary
| | - Gábor Bende
- Department of Biotechnology, University of Szeged, Közép fasor 52, Szeged, 6726, Hungary.,Institute of Biophysics, Biological Research Center, Temesvári krt. 62, Szeged, 6726, Hungary
| | - Naila Bounedjoum
- Department of Biotechnology, University of Szeged, Közép fasor 52, Szeged, 6726, Hungary
| | - Gergely Maróti
- Seqomics Ltd, Mórahalom, Vállalkozók útja 7, Mórahalom, 6782, Hungary
| | - Krisztián Laczi
- Department of Biotechnology, University of Szeged, Közép fasor 52, Szeged, 6726, Hungary
| | - Márk Szuhaj
- Department of Biotechnology, University of Szeged, Közép fasor 52, Szeged, 6726, Hungary
| | - Katalin Perei
- Department of Biotechnology, University of Szeged, Közép fasor 52, Szeged, 6726, Hungary
| | - Gábor Rákhely
- Department of Biotechnology, University of Szeged, Közép fasor 52, Szeged, 6726, Hungary. .,Institute of Biophysics, Biological Research Center, Temesvári krt. 62, Szeged, 6726, Hungary. .,Institute of Environmental and Technological Sciences, Közép fasor 52, Szeged, 6726, Hungary.
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6
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Cillingová A, Zeman I, Tóth R, Neboháčová M, Dunčková I, Hölcová M, Jakúbková M, Gérecová G, Pryszcz LP, Tomáška Ľ, Gabaldón T, Gácser A, Nosek J. Eukaryotic transporters for hydroxyderivatives of benzoic acid. Sci Rep 2017; 7:8998. [PMID: 28827635 PMCID: PMC5566891 DOI: 10.1038/s41598-017-09408-6] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2017] [Accepted: 07/24/2017] [Indexed: 11/09/2022] Open
Abstract
Several yeast species catabolize hydroxyderivatives of benzoic acid. However, the nature of carriers responsible for transport of these compounds across the plasma membrane is currently unknown. In this study, we analyzed a family of genes coding for permeases belonging to the major facilitator superfamily (MFS) in the pathogenic yeast Candida parapsilosis. Our results revealed that these transporters are functionally equivalent to bacterial aromatic acid: H+ symporters (AAHS) such as GenK, MhbT and PcaK. We demonstrate that the genes HBT1 and HBT2 encoding putative transporters are highly upregulated in C. parapsilosis cells assimilating hydroxybenzoate substrates and the corresponding proteins reside in the plasma membrane. Phenotypic analyses of knockout mutants and hydroxybenzoate uptake assays provide compelling evidence that the permeases Hbt1 and Hbt2 transport the substrates that are metabolized via the gentisate (3-hydroxybenzoate, gentisate) and 3-oxoadipate pathway (4-hydroxybenzoate, 2,4-dihydroxybenzoate and protocatechuate), respectively. Our data support the hypothesis that the carriers belong to the AAHS family of MFS transporters. Phylogenetic analyses revealed that the orthologs of Hbt permeases are widespread in the subphylum Pezizomycotina, but have a sparse distribution among Saccharomycotina lineages. Moreover, these analyses shed additional light on the evolution of biochemical pathways involved in the catabolic degradation of hydroxyaromatic compounds.
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Affiliation(s)
- Andrea Cillingová
- Departments of Biochemistry and Genetics, Comenius University in Bratislava, Faculty of Natural Sciences, Ilkovičova 6, 842 15, Bratislava, Slovak Republic
| | - Igor Zeman
- Departments of Biochemistry and Genetics, Comenius University in Bratislava, Faculty of Natural Sciences, Ilkovičova 6, 842 15, Bratislava, Slovak Republic
| | - Renáta Tóth
- Department of Microbiology, University of Szeged, Szeged, Közép fasor 52, H-6726, Szeged, Hungary
| | - Martina Neboháčová
- Departments of Biochemistry and Genetics, Comenius University in Bratislava, Faculty of Natural Sciences, Ilkovičova 6, 842 15, Bratislava, Slovak Republic
| | - Ivana Dunčková
- Departments of Biochemistry and Genetics, Comenius University in Bratislava, Faculty of Natural Sciences, Ilkovičova 6, 842 15, Bratislava, Slovak Republic
| | - Mária Hölcová
- Departments of Biochemistry and Genetics, Comenius University in Bratislava, Faculty of Natural Sciences, Ilkovičova 6, 842 15, Bratislava, Slovak Republic
| | - Michaela Jakúbková
- Departments of Biochemistry and Genetics, Comenius University in Bratislava, Faculty of Natural Sciences, Ilkovičova 6, 842 15, Bratislava, Slovak Republic
| | - Gabriela Gérecová
- Departments of Biochemistry and Genetics, Comenius University in Bratislava, Faculty of Natural Sciences, Ilkovičova 6, 842 15, Bratislava, Slovak Republic.,Department of Biochemistry and Cell Biology, Max F. Perutz Laboratories, University of Vienna, Dr. Bohr Gasse 9, 1030, Vienna, Austria
| | - Leszek P Pryszcz
- Bioinformatics and Genomics Programme, Centre for Genomic Regulation, Doctor Aiguader 88, 08003, Barcelona, Spain.,International Institute of Molecular and Cell Biology in Warsaw, 4 Trojdena Street, 02-109, Warsaw, Poland
| | - Ľubomír Tomáška
- Departments of Biochemistry and Genetics, Comenius University in Bratislava, Faculty of Natural Sciences, Ilkovičova 6, 842 15, Bratislava, Slovak Republic
| | - Toni Gabaldón
- Bioinformatics and Genomics Programme, Centre for Genomic Regulation, Doctor Aiguader 88, 08003, Barcelona, Spain.,Departament de Ciències Experimentals I de la Salut, Universitat Pompeu Fabra, 08003, Barcelona, Spain.,Institució Catalana de Recerca i Estudis Avançats, Pg. Lluís Companys 23, 08010, Barcelona, Spain
| | - Attila Gácser
- Department of Microbiology, University of Szeged, Szeged, Közép fasor 52, H-6726, Szeged, Hungary
| | - Jozef Nosek
- Departments of Biochemistry and Genetics, Comenius University in Bratislava, Faculty of Natural Sciences, Ilkovičova 6, 842 15, Bratislava, Slovak Republic.
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Mutations in the β-Subunit of the RNA Polymerase Impair the Surface-Associated Motility and Virulence of Acinetobacter baumannii. Infect Immun 2017; 85:IAI.00327-17. [PMID: 28507065 DOI: 10.1128/iai.00327-17] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2017] [Accepted: 05/08/2017] [Indexed: 12/19/2022] Open
Abstract
Acinetobacter baumannii is a major cause of antibiotic-resistant nosocomial infections worldwide. In this study, several rifampin-resistant spontaneous mutants obtained from the A. baumannii ATCC 17978 strain that differed in their point mutations in the rpoB gene, encoding the β-subunit of the RNA polymerase, were isolated. All the mutants harboring amino acid substitutions in position 522 or 540 of the RpoB protein were impaired in surface-associated motility and had attenuated virulence in the fertility model of Caenorhabditis elegans The transcriptional profile of these mutants included six downregulated genes encoding proteins homologous to transporters and metabolic enzymes widespread among A. baumannii clinical isolates. The construction of knockout mutants in each of the six downregulated genes revealed a significant reduction in the surface-associated motility and virulence of four of them in the A. baumannii ATCC 17978 strain, as well as in the virulent clinical isolate MAR002. Taken together, our results provide strong evidence of the connection between motility and virulence in this multiresistant nosocomial pathogen.
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8
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γ-Resorcylate catabolic-pathway genes in the soil actinomycete Rhodococcus jostii RHA1. Appl Environ Microbiol 2015; 81:7656-65. [PMID: 26319878 DOI: 10.1128/aem.02422-15] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2015] [Accepted: 08/19/2015] [Indexed: 11/20/2022] Open
Abstract
The Rhodococcus jostii RHA1 gene cluster required for γ-resorcylate (GRA) catabolism was characterized. The cluster includes tsdA, tsdB, tsdC, tsdD, tsdR, tsdT, and tsdX, which encode GRA decarboxylase, resorcinol 4-hydroxylase, hydroxyquinol 1,2-dioxygenase, maleylacetate reductase, an IclR-type regulator, a major facilitator superfamily transporter, and a putative hydrolase, respectively. The tsdA gene conferred GRA decarboxylase activity on Escherichia coli. Purified TsdB oxidized NADH in the presence of resorcinol, suggesting that tsdB encodes a unique NADH-specific single-component resorcinol 4-hydroxylase. Mutations in either tsdA or tsdB resulted in growth deficiency on GRA. The tsdC and tsdD genes conferred hydroxyquinol 1,2-dioxygenase and maleylacetate reductase activities, respectively, on E. coli. Inactivation of tsdT significantly retarded the growth of RHA1 on GRA. The growth retardation was partially suppressed under acidic conditions, suggesting the involvement of tsdT in GRA uptake. Reverse transcription-PCR analysis revealed that the tsd genes constitute three transcriptional units, the tsdBADC and tsdTX operons and tsdR. Transcription of the tsdBADC and tsdTX operons was induced during growth on GRA. Inactivation of tsdR derepressed transcription of the tsdBADC and tsdTX operons in the absence of GRA, suggesting that tsd gene transcription is negatively regulated by the tsdR-encoded regulator. Binding of TsdR to the tsdR-tsdB and tsdT-tsdR intergenic regions was inhibited by the addition of GRA, indicating that GRA interacts with TsdR as an effector molecule.
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9
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Luu RA, Kootstra JD, Nesteryuk V, Brunton CN, Parales JV, Ditty JL, Parales RE. Integration of chemotaxis, transport and catabolism inPseudomonas putidaand identification of the aromatic acid chemoreceptor PcaY. Mol Microbiol 2015; 96:134-47. [DOI: 10.1111/mmi.12929] [Citation(s) in RCA: 49] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/07/2015] [Indexed: 11/28/2022]
Affiliation(s)
- Rita A. Luu
- Department of Microbiology and Molecular Genetics; College of Biological Sciences; University of California; Davis CA USA
| | - Joshua D. Kootstra
- Department of Microbiology and Molecular Genetics; College of Biological Sciences; University of California; Davis CA USA
| | - Vasyl Nesteryuk
- Department of Microbiology and Molecular Genetics; College of Biological Sciences; University of California; Davis CA USA
| | - Ceanne N. Brunton
- Department of Microbiology and Molecular Genetics; College of Biological Sciences; University of California; Davis CA USA
| | - Juanito V. Parales
- Department of Microbiology and Molecular Genetics; College of Biological Sciences; University of California; Davis CA USA
| | - Jayna L. Ditty
- Department of Biology; University of St. Thomas; St. Paul MN USA
| | - Rebecca E. Parales
- Department of Microbiology and Molecular Genetics; College of Biological Sciences; University of California; Davis CA USA
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Banigan JR, Gayen A, Cho MK, Traaseth NJ. A structured loop modulates coupling between the substrate-binding and dimerization domains in the multidrug resistance transporter EmrE. J Biol Chem 2014; 290:805-14. [PMID: 25406320 DOI: 10.1074/jbc.m114.601963] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Secondary active transporters undergo large conformational changes to facilitate the efflux of substrates across the lipid bilayer. Among the smallest known transport proteins are members of the small multidrug resistance (SMR) family that are composed of four transmembrane (TM) domains and assemble into dimers. An unanswered question in the SMR field is how the dimerization domain (TM4) is coupled with the substrate-binding chamber (TM1-3). To provide insight for this essential aspect of ion-coupled transport, we carried out a structure-function study on the SMR protein EmrE using solid-state NMR spectroscopy in lipid bilayers and resistance assays in Escherichia coli. The chemical shifts for EmrE were consistent with β-strand secondary structure for the loop connecting TM3 and TM4. Based on these structural results, EmrE mutants were created to ascertain whether a specific loop length and composition were necessary for function. A linker encompassing six extra Gly residues relative to wild-type EmrE failed to give resistance; however, the number of residues in the loop was not the only criterion for a functional efflux pump. Replacement of the central hydrophobic residue with Gly (L83G) also conferred no ethidium resistance phenotype, which supported the conclusion that the structure and length of the loop were both essential for ion-coupled transport. Taken together with a bioinformatics analysis, a structured linker is likely conserved across the SMR family to play an active role in mediating the conformational switch between inward-open and outward-open states necessary for drug efflux. These findings underscore the important role loops can play in mediating efflux.
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Affiliation(s)
- James R Banigan
- From the Department of Chemistry, New York University, New York, New York 10003
| | - Anindita Gayen
- From the Department of Chemistry, New York University, New York, New York 10003
| | - Min-Kyu Cho
- From the Department of Chemistry, New York University, New York, New York 10003
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11
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Pernstich C, Senior L, MacInnes KA, Forsaith M, Curnow P. Expression, purification and reconstitution of the 4-hydroxybenzoate transporter PcaK from Acinetobacter sp. ADP1. Protein Expr Purif 2014; 101:68-75. [PMID: 24907408 PMCID: PMC4148202 DOI: 10.1016/j.pep.2014.05.011] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2014] [Revised: 05/20/2014] [Accepted: 05/23/2014] [Indexed: 11/19/2022]
Abstract
The aromatic acid transporter PcaK was recombinantly expressed and purified. PcaK is a stable homotrimer in n-dodecyl-β-d-maltoside. A reconstituted assay shows asymmetric transport. The electrical component of the proton gradient drives transport. Unexpectedly, PcaK is active in transporting 2-hydroxybenzoates.
The aromatic acid:H+ symporter family of integral membrane proteins play an important role in the microbial metabolism of aromatic compounds. Here, we show that the 4-hydroxybenzoate transporter from Acinetobacter sp. ADP1, PcaK, can be successfully overexpressed in Escherichia coli and purified by affinity chromatography. Affinity-purified PcaK is a stable, monodisperse homotrimer in the detergent n-dodecyl-β-d-maltopyranoside supplemented with cholesteryl hemisuccinate. The purified protein has α-helical secondary structure and can be reconstituted to a functional state in synthetic proteoliposomes. Asymmetric substrate transport was observed when proteoliposomes were energized by applying an electrochemical proton gradient (Δμ‾H+) or a membrane potential (ΔΨ) but not by ΔpH alone. PcaK was selective in transporting 4-hydroxybenzoate and 3,4-dihydroxybenzoate over closely related compounds, confirming previous reports on substrate specificity. However, PcaK also showed an unexpected preference for transporting 2-hydroxybenzoates. These results provide the basis for further detailed studies of the structure and function of this family of transporters.
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Affiliation(s)
| | - Laura Senior
- School of Biochemistry, University of Bristol, Bristol BS8 1TD, UK; Bristol Centre for Functional Nanomaterials, University of Bristol, Bristol BS8 1TD, UK
| | | | - Marc Forsaith
- School of Biochemistry, University of Bristol, Bristol BS8 1TD, UK
| | - Paul Curnow
- School of Biochemistry, University of Bristol, Bristol BS8 1TD, UK.
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12
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Picossi S, Flores E, Ekman M. Diverse roles of the GlcP glucose permease in free-living and symbiotic cyanobacteria. PLANT SIGNALING & BEHAVIOR 2013; 8:e27416. [PMID: 24675169 PMCID: PMC4091242 DOI: 10.4161/psb.27416] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/29/2013] [Accepted: 12/03/2013] [Indexed: 06/03/2023]
Abstract
Certain cyanobacteria can form symbiotic associations with plants, where the symbiont supplies the plant partner with nitrogen and in return obtains sugars. We recently showed that in the symbiotic cyanobacterium Nostoc punctiforme, a glucose specific permease, GlcP, is necessary for the symbiosis to be formed. Results presented here from growth yield measurements of mutant strains with inactivated or overexpressing sugar transporters suggest that GlcP could be induced by a symbiosis specific substance. We also discuss that the transporter may have a role other than nutritional once the symbiosis is established, i.e., during infection, and more specifically in the chemotaxis of the symbiont. Phylogenetic analysis shows that the distribution of GlcP among cyanobacteria is likely influenced by horizontal gene transfer, but also that it is not correlated with symbiotic competence. Instead, regulatory patterns of the transporter in Nostoc punctiforme likely constitute symbiosis specific adaptations.
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13
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mhpT encodes an active transporter involved in 3-(3-hydroxyphenyl)propionate catabolism by Escherichia coli K-12. Appl Environ Microbiol 2013; 79:6362-8. [PMID: 23934492 DOI: 10.1128/aem.02110-13] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Escherichia coli K-12 utilizes 3-(3-hydroxyphenyl)propionate (3HPP) as a sole carbon and energy source. Among the genes in its catabolic cluster in the genome, mhpT was proposed to encode a hypothetical transporter. Since no transporter for 3HPP uptake has been identified, we investigated whether MhpT is responsible for 3HPP uptake. MhpT fused with green fluorescent protein was found to be located at the periphery of cells by confocal microscopy, consistent with localization to the cytoplasmic membrane. Gene knockout and complementation studies clearly indicated that mhpT is essential for 3HPP catabolism in E. coli K-12 W3110 at pH 8.2. Uptake assays with (14)C-labeled substrates demonstrated that strain W3110 and strain W3110ΔmhpT containing recombinant MhpT specifically transported 3HPP but not benzoate, 3-hydroxybenzoate, or gentisate into cells. Energy dependence assays suggested that MhpT-mediated 3HPP transport was driven by the proton motive force. The change of Ala-272 of MhpT to a histidine, surprisingly, resulted in enhanced transport activity, and strain W3110ΔmhpT containing the MhpT A272H mutation had a slightly higher growth rate than the wild-type strain at pH 8.2. Hence, we demonstrated that MhpT is a specific 3HPP transporter and vital for E. coli K-12 W3110 growth on this substrate under basic conditions.
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Taxis of Pseudomonas putida F1 toward phenylacetic acid is mediated by the energy taxis receptor Aer2. Appl Environ Microbiol 2013; 79:2416-23. [PMID: 23377939 DOI: 10.1128/aem.03895-12] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
The phenylacetic acid (PAA) degradation pathway is a widely distributed funneling pathway for the catabolism of aromatic compounds, including the environmental pollutants styrene and ethylbenzene. However, bacterial chemotaxis to PAA has not been studied. The chemotactic strain Pseudomonas putida F1 has the ability to utilize PAA as a sole carbon and energy source. We identified a putative PAA degradation gene cluster (paa) in P. putida F1 and demonstrated that PAA serves as a chemoattractant. The chemotactic response was induced during growth with PAA and was dependent on PAA metabolism. A functional cheA gene was required for the response, indicating that PAA is sensed through the conserved chemotaxis signal transduction system. A P. putida F1 mutant lacking the energy taxis receptor Aer2 was deficient in PAA taxis, indicating that Aer2 is responsible for mediating the response to PAA. The requirement for metabolism and the role of Aer2 in the response indicate that P. putida F1 uses energy taxis to detect PAA. We also revealed that PAA is an attractant for Escherichia coli; however, a mutant lacking a functional Aer energy receptor had a wild-type response to PAA in swim plate assays, suggesting that PAA is detected through a different mechanism in E. coli. The role of Aer2 as an energy taxis receptor provides the potential to sense a broad range of aromatic growth substrates as chemoattractants. Since chemotaxis has been shown to enhance the biodegradation of toxic pollutants, the ability to sense PAA gradients may have implications for the bioremediation of aromatic hydrocarbons that are degraded via the PAA pathway.
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Xu Y, Wang SH, Chao HJ, Liu SJ, Zhou NY. Biochemical and molecular characterization of the gentisate transporter GenK in Corynebacterium glutamicum. PLoS One 2012; 7:e38701. [PMID: 22808015 PMCID: PMC3392265 DOI: 10.1371/journal.pone.0038701] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2012] [Accepted: 05/11/2012] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND Gentisate (2,5-dihydroxybenzoate) is a key ring-cleavage substrate involved in various aromatic compounds degradation. Corynebacterium glutamicum ATCC13032 is capable of growing on gentisate and genK was proposed to encode a transporter involved in this utilization by its disruption in the restriction-deficient mutant RES167. Its biochemical characterization by uptake assay using [(14)C]-labeled gentisate has not been previously reported. METHODOLOGY/PRINCIPAL FINDINGS In this study, biochemical characterization of GenK by uptake assays with [(14)C]-labeled substrates demonstrated that it specifically transported gentisate into the cells with V(max) and K(m) of 3.06 ± 0.16 nmol/min/mg of dry weight and 10.71 ± 0.11 µM respectively, and no activity was detected for either benzoate or 3-hydoxybenzoate. When GenK was absent in strain RES167 ΔgenK, it retained 85% of its original transport activity at pH 6.5 compared to that of strain RES167. However, it lost 79% and 88% activity at pH 7.5 and 8.0, respectively. A number of competing substrates, including 3-hydroxybenzoate, benzoate, protocatechuate and catechol, significantly inhibited gentisate uptake by more than 40%. Through site-directed mutagenesis, eight amino acid residues of GenK, Asp-54, Asp-57 and Arg-386 in the hydrophobic transmembrane regions and Arg-103, Trp-309, Asp-312, Arg-313 and Ile-317 in the hydrophilic cytoplasmic loops were shown to be important for gentisate transport. When conserved residues Asp-54 and Asp-57 respectively were changed to glutamate, both mutants retained approximately 50% activity and were able to partially complement the ability of strain RES167 ΔgenK to grow on gentisate. CONCLUSIONS/SIGNIFICANCE Our results demonstrate that GenK is an active gentisate transporter in Corynebacterium glutamicum ATCC13032. The GenK-mediated gentisate transport was also shown to be a limiting step for the gentisate utilization by this strain. This enhances our understanding of gentisate transport in the microbial degradation of aromatic compounds.
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Affiliation(s)
- Ying Xu
- Key Laboratory of Agricultural and Environmental Microbiology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, China
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16
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MhbT is a specific transporter for 3-hydroxybenzoate uptake by Gram-negative bacteria. Appl Environ Microbiol 2012; 78:6113-20. [PMID: 22729544 DOI: 10.1128/aem.01511-12] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Klebsiella pneumoniae M5a1 is capable of utilizing 3-hydroxybenzoate via gentisate, and the 6.3-kb gene cluster mhbRTDHIM conferred the ability to grow on 3-hydroxybenzoate to Escherichia coli and Pseudomonas putida PaW340. Four of the six genes (mhbDHIM) encode enzymes converting 3-hydroxybenzoate to pyruvate and fumarate via gentisate. MhbR is a gene activator, and MhbT is a hypothetical protein belonging to the transporter of the aromatic acid/H(+) symporter family. Since a transporter for 3-hydrxybenzoate uptake has not been characterized to date, we investigated whether MhbT is responsible for the uptake of 3-hydroxybenzoate, its metabolic intermediate gentisate, or both. The MhbT-green fluorescent protein (GFP) fusion protein was located on the cytoplasmic membrane. P. putida PaW340 containing mhbRΔTDHIM could not grow on 3-hydroxybenzoate; however, supplying mhbT in trans allowed the bacterium to grow on the substrate. K. pneumoniae M5a1 and P. putida PaW340 containing recombinant MhbT transported (14)C-labeled 3-hydroxybenzoate but not (14)C-labeled gentisate and benzoate into the cells. Site-directed mutagenesis of two conserved amino acid residues (Asp-82 and Asp-314) and a less-conserved residue (Val-311) among the members of the symporter family in the hydrophilic cytoplasmic loops resulted in the loss of 3-hydroxybenzoate uptake by P. putida PaW340 carrying the mutant proteins. Hence, we demonstrated that MhbT is a specific 3-hydroxybenzoate transporter.
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17
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Kapoor K, Rehan M, Kaushiki A, Pasrija R, Lynn AM, Prasad R. Rational mutational analysis of a multidrug MFS transporter CaMdr1p of Candida albicans by employing a membrane environment based computational approach. PLoS Comput Biol 2009; 5:e1000624. [PMID: 20041202 PMCID: PMC2789324 DOI: 10.1371/journal.pcbi.1000624] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2009] [Accepted: 11/20/2009] [Indexed: 01/31/2023] Open
Abstract
CaMdr1p is a multidrug MFS transporter of pathogenic Candida albicans. An over-expression of the gene encoding this protein is linked to clinically encountered azole resistance. In-depth knowledge of the structure and function of CaMdr1p is necessary for an effective design of modulators or inhibitors of this efflux transporter. Towards this goal, in this study, we have employed a membrane environment based computational approach to predict the functionally critical residues of CaMdr1p. For this, information theoretic scores which are variants of Relative Entropy (Modified Relative Entropy RE(M)) were calculated from Multiple Sequence Alignment (MSA) by separately considering distinct physico-chemical properties of transmembrane (TM) and inter-TM regions. The residues of CaMdr1p with high RE(M) which were predicted to be significantly important were subjected to site-directed mutational analysis. Interestingly, heterologous host Saccharomyces cerevisiae, over-expressing these mutant variants of CaMdr1p wherein these high RE(M) residues were replaced by either alanine or leucine, demonstrated increased susceptibility to tested drugs. The hypersensitivity to drugs was supported by abrogated substrate efflux mediated by mutant variant proteins and was not attributed to their poor expression or surface localization. Additionally, by employing a distance plot from a 3D deduced model of CaMdr1p, we could also predict the role of these functionally critical residues in maintaining apparent inter-helical interactions to provide the desired fold for the proper functioning of CaMdr1p. Residues predicted to be critical for function across the family were also found to be vital from other previously published studies, implying its wider application to other membrane protein families.
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Affiliation(s)
- Khyati Kapoor
- School of Life Sciences, Jawaharlal Nehru University, New Delhi, India
| | - Mohd Rehan
- School of Information Technology, Jawaharlal Nehru University, New Delhi, India
| | - Ajeeta Kaushiki
- School of Information Technology, Jawaharlal Nehru University, New Delhi, India
| | - Ritu Pasrija
- School of Life Sciences, Jawaharlal Nehru University, New Delhi, India
| | - Andrew M. Lynn
- School of Information Technology, Jawaharlal Nehru University, New Delhi, India
| | - Rajendra Prasad
- School of Life Sciences, Jawaharlal Nehru University, New Delhi, India
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Bobadilla Fazzini RA, Bielecka A, Poucas Quintas AK, Golyshin PN, Preto MJ, Timmis KN, Martins dos Santos VAP. Bacterial consortium proteomics under 4-chlorosalicylate carbon-limiting conditions. Proteomics 2009; 9:2273-85. [DOI: 10.1002/pmic.200800489] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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19
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Chaudhry MT, Huang Y, Shen XH, Poetsch A, Jiang CY, Liu SJ. Genome-wide investigation of aromatic acid transporters in Corynebacterium glutamicum. MICROBIOLOGY-SGM 2007; 153:857-865. [PMID: 17322206 DOI: 10.1099/mic.0.2006/002501-0] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Genome-wide data mining indicated that six genes (ncgl1031, ncgl2302, ncgl2325, ncgl2326, ncgl2922 and ncgl2953) encoding putative transport proteins are involved in uptake of various aromatic compounds that are further degraded through the beta-ketoadipate, gentisate and resorcinol pathways in Corynebacterium glutamicum. The gentisate (GenK/NCgl2922) and vanillate (VanK/NCgl2302) transporters have been identified previously. In this study, physiological functions of the remaining four putative transporters as well as the vanillate transporter (VanK/NCgl2302) were examined by genetic disruption/complementation and uptake assays. Results indicated that ncgl1031 encodes PcaK for 4-hydroxybenzoate and protocatechuate transport, and ncgl2302 encodes VanK for vanillate transport. Genetic studies and uptake assays indicated that both ncgl2325/benK and ncgl2326/benE are involved in benzoate transport in C. glutamicum. When growth rates were compared for two benzoate transporter mutants, benK and benE, a high growth rate was observed for the benE mutant. Sequence alignments revealed that PcaK, VanK, BenK and GenK belong to the major facilitator superfamily (MFS). Modelling of secondary structures based on previously characterized MFS members revealed that NCgl1031, NCgl2302, NCgl2325 and NCgl2922 are typical 12 helix transmembrane proteins but NCgl2326 contains only 11 alpha-helices. Thus the functionally identified NCgl2326 belongs to a novel type of benzoate transporters. Attempts to identify the phenotype of a hydK/ncgl2953 mutant failed, so the function of ncgl2953 remains unclear.
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Affiliation(s)
- Muhammad Tausif Chaudhry
- Graduate University of Chinese Academy of Sciences, Beijing, 100049, China
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing, 100080, China
| | - Yan Huang
- Graduate University of Chinese Academy of Sciences, Beijing, 100049, China
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing, 100080, China
| | - Xi-Hui Shen
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing, 100080, China
| | - Ansgar Poetsch
- Lehrstuhl für Biochemie der Pflanzen, Ruhr Universität, Bochum, Germany
| | - Cheng-Ying Jiang
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing, 100080, China
| | - Shuang-Jiang Liu
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing, 100080, China
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20
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O'Sullivan LA, Weightman AJ, Jones TH, Marchbank AM, Tiedje JM, Mahenthiralingam E. Identifying the genetic basis of ecologically and biotechnologically useful functions of the bacterium Burkholderia vietnamiensis. Environ Microbiol 2007; 9:1017-34. [PMID: 17359273 DOI: 10.1111/j.1462-2920.2006.01228.x] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Signature-tagged mutagenesis (STM) was used to identify genetic determinants of fitness associated with two key ecological processes mediated by bacteria. Burkholderia vietnamiensis strain G4 was used as a model bacterium to investigate: phenol degradation as a model of bioremediation, and pea rhizosphere colonization as a prerequisite to biological control and phytoremediation. A total of 1900 mutants were screened and 196 putative fitness mutants identified; the genetic basis of 137 of these mutations was determined by correlation to the G4 genome. The phenol-STM screen was more successful at identifying phenol degradation mutations (83 mutants; 4.4% hit rate) than a conventional agar-based phenol screen (49 mutants, 5319 screened, 0.92% hit rate). The combination of both screens completely defined the components of the TOM pathway in strain G4 and also identified novel accessory genes not previously implicated in phenol utilization. The rhizosphere-STM screen identified 113 mutants (5.9% hit rate); 107 had reduced tag signals indicative of poor rhizosphere colonization (Rhiz-), while six mutants produced high hybridization signals suggesting increased rhizosphere competence (Rhiz+). Competition assays confirmed that 69% of Rhiz- mutants tested (24/35) were severely compromised in their rhizosphere fitness. Seventy Rhiz- mutations mapped to genes with the following putative functions: amino acid biosynthesis (25; 36%), general metabolism (18; 26%), hypothetical (9; 13%), regulatory genes (4; 5.7%), transport and stress (2 each; 2.8% respectively). One of the most interesting discoveries mediated by the rhizosphere-STM screen was the identification of three Rhiz+ mutants inactivated within a single virulence-associated autotransporter adhesin gene; this mutation consistently produced a hyper-colonization phenotype suggesting a highly novel role for this surface adhesin during plant interactions. Our study has shown that STM can be successfully applied to ecologically important microbial interactions, defining the underlying genetic systems important for biotechnological fitness of environmental bacteria such those from the Burkholderia cepacia complex.
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Affiliation(s)
- Louise A O'Sullivan
- Cardiff School of Biosciences, Cardiff University, Main Building, Park Place, Cardiff CF10 3TL, UK
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21
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Xu Y, Yan DZ, Zhou NY. Heterologous expression and localization of gentisate transporter Ncg12922 from Corynebacterium glutamicum ATCC 13032. Biochem Biophys Res Commun 2006; 346:555-61. [PMID: 16765316 DOI: 10.1016/j.bbrc.2006.05.143] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2006] [Accepted: 05/23/2006] [Indexed: 10/24/2022]
Abstract
Ralstonia sp. strain U2 metabolizes naphthalene via gentisate (2,5-dihydroxybenzoate) to central metabolites, but it was found unable to utilize gentisate as growth substrate. A putative gentisate transporter encoded by ncg12922 from Corynebacterium glutamicum ATCC 13032 was functionally expressed in Ralstonia sp. strain U2, converting strain U2 to a gentisate utilizer. After ncg12922 was inserted into plasmid pGFPe with green fluorescence protein gene gfp, the expressed fusion protein Ncg12922-GFP could be visualized in the periphery of Escherichia coli cells under confocal microscope, consistent with a cytoplasmic membrane location. In contrast, GFP was ubiquitous in the cytoplasm of E. coli cells carrying pGFPe only. Gentisate 1,2-dioxygenase activity was present in the cell extract from strain U2 induced with gentisate but at a much lower level (one-fifth) than that obtained with salicylate. However, it exhibited a similar level in strain U2 containing Ncg12922 induced either by salicylate or gentisate.
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Affiliation(s)
- Ying Xu
- Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, China
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22
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Parales RE. Nitrobenzoates and aminobenzoates are chemoattractants for Pseudomonas strains. Appl Environ Microbiol 2004; 70:285-92. [PMID: 14711654 PMCID: PMC321308 DOI: 10.1128/aem.70.1.285-292.2004] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Three Pseudomonas strains were tested for the ability to sense and respond to nitrobenzoate and aminobenzoate isomers in chemotaxis assays. Pseudomonas putida PRS2000, a strain that grows on benzoate and 4-hydroxybenzoate by using the beta-ketoadipate pathway, has a well-characterized beta-ketoadipate-inducible chemotactic response to aromatic acids. PRS2000 was chemotactic to 3- and 4-nitrobenzoate and all three isomers of aminobenzoate when grown under conditions that induce the benzoate chemotactic response. P. putida TW3 and Pseudomonas sp. strain 4NT grow on 4-nitrotoluene and 4-nitrobenzoate by using the ortho (beta-ketoadipate) and meta pathways, respectively, to complete the degradation of protocatechuate derived from 4-nitrotoluene and 4-nitrobenzoate. However, based on results of catechol 1,2-dioxygenase and catechol 2,3-dioxygenase assays, both strains were found to use the beta-ketoadipate pathway for the degradation of benzoate. Both strains were chemotactic to benzoate, 3- and 4-nitrobenzoate, and all three aminobenzoate isomers after growth with benzoate but not succinate. Strain TW3 was chemotactic to the same set of aromatic compounds after growth with 4-nitrotoluene or 4-nitrobenzoate. In contrast, strain 4NT did not respond to any aromatic acids when grown with 4-nitrotoluene or 4-nitrobenzoate, apparently because these substrates are not metabolized to the inducer (beta-ketoadipate) of the chemotaxis system. The results suggest that strains TW3 and 4NT have a beta-ketoadipate-inducible chemotaxis system that responds to a wide range of aromatic acids and is quite similar to that present in PRS2000. The broad specificity of this chemotaxis system works as an advantage in strains TW3 and 4NT because it functions to detect diverse carbon sources, including 4-nitrobenzoate.
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Affiliation(s)
- Rebecca E Parales
- Section of Microbiology, University of California, Davis, California 95616, USA.
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23
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Aguilera S, Aguilar ME, Chávez MP, López-Meza JE, Pedraza-Reyes M, Campos-García J, Cervantes C. Essential residues in the chromate transporter ChrA ofPseudomonas aeruginosa. FEMS Microbiol Lett 2004; 232:107-12. [PMID: 15019742 DOI: 10.1016/s0378-1097(04)00068-0] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2003] [Revised: 01/06/2004] [Accepted: 01/12/2004] [Indexed: 11/19/2022] Open
Abstract
The chrA gene of Pseudomonas aeruginosa plasmid pUM505 encodes the hydrophobic protein ChrA, which confers resistance to chromate by the energy-dependent efflux of chromate ions. Chromate-sensitive mutants were isolated by in vivo random mutagenesis. Transport experiments with cell suspensions of selected mutants showed that 51CrO4(2-) extrusion was drastically lowered as compared to suspensions of the strain with the wild-type plasmid, confirming that the mutations affected a chromate efflux system. DNA sequence analysis showed that most point mutations affected amino acids clustered in the N-terminal half of ChrA, altering either cytoplasmic regions or transmembrane segments, and replaced residues moderately to highly conserved in ChrA homologs. PhoA and LacZ translational fusions were used to confirm the membrane topology at the N-terminal half of the ChrA protein.
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Affiliation(s)
- Selene Aguilera
- Instituto de Investigaciones Químico-Biológicas, Universidad Michoacana, Edificio B-3, Ciudad Universitaria, 58030 Morelia, Mich., Mexico
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25
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Simmons CR, Fridlender M, Navarro PA, Yalpani N. A maize defense-inducible gene is a major facilitator superfamily member related to bacterial multidrug resistance efflux antiporters. PLANT MOLECULAR BIOLOGY 2003; 52:433-46. [PMID: 12856948 DOI: 10.1023/a:1023982704901] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
A defense-inducible maize gene was discovered through global mRNA profiling analysis. Its mRNA expression is induced by pathogens and defense-related conditions in various tissues involving both resistant and susceptible interactions. These include Cochliobolus heterostrophus and Cochliobolus carbonum infection, ultraviolet light treatment, the Les9 disease lesion mimic background, and plant tissues engineered to express flavonoids or the avirulence gene avrRxv. The gene was named Zm-mfs1 after it was found to encode a protein related to the major facilitator superfamily (MFS) of intregral membrane permeases. It is most closely related to the bacterial multidrug efflux protein family, typified by the Escherichia coli TetA, which are proton motive force antiporters that export antimicrobial drugs and other compounds, but which can be also involved in potassium export/proton import or potassium re-uptake. Other related plant gene sequences in maize, rice, and Arabidopsis were identified, three of which are introduced here. Among this new plant MFS subfamily, the characteristic MFS motif in cytoplasmic TM2-TM3 loop, and the antiporter family motif in transmembrane domain TM5 are both conserved, however the TM7 and the cytoplasmic TM8-TM9 loop are divergent from those of the bacterial multidrug transporters. We hypothesize that Zm-Mfs1 is a prototype of a new class of plant defense-related proteins that could be involved in either of three nonexclusive roles: (1) export of antimicrobial compounds produced by plant pathogens; (2) export of plant-generated antimicrobial compounds; and (3) potassium export and/or re-uptake, as can occur in plant defense reactions.
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MESH Headings
- Amino Acid Sequence
- Antiporters/genetics
- Ascomycota/growth & development
- Blotting, Northern
- DNA, Complementary/chemistry
- DNA, Complementary/genetics
- Drug Resistance, Bacterial/genetics
- Drug Resistance, Multiple/genetics
- Gene Expression Profiling
- Gene Expression Regulation, Plant/radiation effects
- Immunity, Innate/genetics
- Molecular Sequence Data
- Plant Diseases/genetics
- Plant Diseases/microbiology
- Plant Proteins/genetics
- RNA, Messenger/genetics
- RNA, Messenger/metabolism
- Sequence Alignment
- Sequence Analysis, DNA
- Sequence Homology, Amino Acid
- Ultraviolet Rays
- Zea mays/genetics
- Zea mays/microbiology
- Zea mays/radiation effects
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Affiliation(s)
- Carl R Simmons
- Bioinformatics Department, Pioneer Hi-Bred International, Inc., 7300 N.W. 62nd Avenue, Johnston, IA 50131-1004, USA.
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26
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Abstract
There is accumulating evidence that motile bacteria are chemotactically attracted to environmental pollutants that they can degrade. Chemotaxis, the ability of motile bacteria to detect and respond to specific chemicals in the environment, can increase an organism's chances of locating useful sources of carbon, nitrogen and energy, and could thus play an important role in the biodegradation process. Recent evidence demonstrating that chemotaxis and biodegradation genes are coordinately regulated suggests that these processes are intimately linked in nature.
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Affiliation(s)
- Rebecca E Parales
- Department of Microbiology and Center for Biocatalysis and Bioprocessing, 3-730 Bowen Science Building, University of Iowa, Iowa City, Iowa 52242, USA.
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27
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Ditty JL, Harwood CS. Charged amino acids conserved in the aromatic acid/H+ symporter family of permeases are required for 4-hydroxybenzoate transport by PcaK from Pseudomonas putida. J Bacteriol 2002; 184:1444-8. [PMID: 11844776 PMCID: PMC134867 DOI: 10.1128/jb.184.5.1444-1448.2002] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Charged amino acids in the predicted transmembrane portion of PcaK, a permease from Pseudomonas putida that transports 4-hydroxybenzoate (4-HBA), were required for 4-HBA transport, and they were also required for P. putida to have a chemotactic response to 4-HBA. An essential amino acid motif (DGXD) containing aspartate residues is located in the first transmembrane segment of PcaK and is conserved in the aromatic acid/H+ symporter family of the major facilitator superfamily of transporters.
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Affiliation(s)
- Jayna L Ditty
- Department of Microbiology, The University of Iowa, Iowa City, IA 52242, USA
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28
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Hawkins AC, Harwood CS. Chemotaxis of Ralstonia eutropha JMP134(pJP4) to the herbicide 2,4-dichlorophenoxyacetate. Appl Environ Microbiol 2002; 68:968-72. [PMID: 11823246 PMCID: PMC126733 DOI: 10.1128/aem.68.2.968-972.2002] [Citation(s) in RCA: 78] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Ralstonia eutropha JMP134(pJP4) and several other species of motile bacteria can degrade the herbicide 2,4-dichlorophenoxyacetate (2,4-D), but it was not known if bacteria could sense and swim towards 2,4-D by the process of chemotaxis. Wild-type R. eutropha cells were chemotactically attracted to 2,4-D in swarm plate assays and qualitative capillary assays. The chemotactic response was induced by growth with 2,4-D and depended on the presence of the catabolic plasmid pJP4, which harbors the tfd genes for 2,4-D degradation. The tfd cluster also encodes a permease for 2,4-D named TfdK. A tfdK mutant was not chemotactic to 2,4-D, even though it grew at wild-type rates on 2,4-D.
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Affiliation(s)
- Andrew C Hawkins
- Department of Microbiology, Center for Biocatalysis and Bioprocessing, The University of Iowa, Iowa City, IA 52242, USA
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29
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Affiliation(s)
- G Alexandre
- School of Biology, Georgia Institute of Technology, Atlanta, Georgia 30332-0230, USA
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30
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Abstract
The treatment of environmental pollution by microorganisms is a promising technology. Various genetic approaches have been developed and used to optimize the enzymes, metabolic pathways and organisms relevant for biodegradation. New information on the metabolic routes and bottlenecks of degradation is still accumulating, enlarging the available toolbox. With molecular methods allowing the characterization of microbial community structure and activities, the performance of microorganisms under in situ conditions and in concert with the indigenous microflora will become predictable.
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Affiliation(s)
- D H Pieper
- Department of Environmental Biotechnology, Gesellschaft für Biotechnologische Forschung mbH (GBF), Braunschweig, D-38124, Germany.
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