title: Involvement of the Acr3 and DctA anti-porters in arsenite oxidation in Agrobacterium tumefaciens 5A.
abstract: Microbial arsenite (AsIII) oxidation forms a critical piece of the arsenic cycle in nature, though our understanding of how and why microorganisms oxidize AsIII remains rudimentary. Our model organism Agrobacterium tumefaciens 5A contains two distinct ars operons (ars1 and ars2) that are similar in their coding region content. The ars1 operon is located nearby the aio operon that is essential for AsIII oxidation. The AsIII/H(+) anti-porters encoded by acr3-1 and acr3-2 are required for maximal AsIII and antimonite (SbIII) resistance, but acr3-1 (negatively regulated by ArsR-1) appears more active in this regard and also required for AsIII oxidation and expression of aioBA. A malate-phosphate anti-porter DctA is regulated by RpoN and AsIII, and is required for normal growth with malate as a sole carbon source. Qualitatively, a ΔdctA mutant was normal for AsIII oxidation and AsIII/SbIII resistance at metalloid concentrations inhibitory to the Δacr3-1 mutant; however, aioBA induction kinetics was significantly phase-shift delayed. Acr3 involvement in AsIII/SbIII resistance is reasonably well understood, but the role of Acr3 and DctA anti-porters in AsIII oxidation and its regulation is unexpected, and suggests that controlled AsIII trafficking across the cytoplasmic membrane is important to a process understood to occur in the periplasm.
authors.affiliation: Department of Land Resources and Environmental Sciences, Montana State University, Bozeman, MT, 59717, USA.
authors.forename: Yoon-Suk
authors.initials: YS
authors.lastname: Kang
authors.affiliation: Department of Land Resources and Environmental Sciences, Montana State University, Bozeman, MT, 59717, USA.|State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, China.
authors.forename: Zunji
authors.initials: Z
authors.lastname: Shi
authors.affiliation: Department of Chemistry and Biochemistry, Montana State University, Bozeman, MT, 59717, USA.
authors.forename: Brian
authors.initials: B
authors.lastname: Bothner
authors.affiliation: State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, China.
authors.forename: Gejiao
authors.initials: G
authors.lastname: Wang
authors.affiliation: Department of Land Resources and Environmental Sciences, Montana State University, Bozeman, MT, 59717, USA.
authors.forename: Timothy R
authors.initials: TR
authors.lastname: McDermott
mesh_terms: D016960:Agrobacterium tumefaciens / Q000235:genetics / Q000378:metabolism*; D000965:Antimony / Q000378:metabolism; D018053:Arsenites / Q000378:metabolism*; D001426:Bacterial Proteins / Q000235:genetics*; D001692:Biological Transport / Q000235:genetics; D029382:Dicarboxylic Acid Transporters / Q000235:genetics / Q000378:metabolism*; D015964:Gene Expression Regulation, Bacterial / Q000187:drug effects; D008293:Malates / Q000378:metabolism; D009876:Operon; D027361:Organic Anion Transporters / Q000235:genetics*; D010084:Oxidation-Reduction
chemical_list: D018053:Arsenites; D001426:Bacterial Proteins; D029382:Dicarboxylic Acid Transporters; D008293:Malates; D027361:Organic Anion Transporters; C098940:malate permease protein, Bacteria; C061374:antimonite; C030298:malic acid; D000965:Antimony; C015001:arsenite