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Arsenite oxidase also functions as an antimonite oxidase

  • Tom Osborne
    ,
  • Qian Wang
    ,
  • Thomas P. Warelow
    ,
  • Yoon-Suk Kang
    ,
  • Christine Romano
    ,
  • Thomas H. Osborne
  • Huazhong Agricultural University
    ,
  • University College London
    ,
  • Montana State University
    ,
  • Oregon Health and Science University
    ,
  • California Polytechnic State University, San Luis Obispo
Research Output: Contribution to journal Article Peer-review

Abstract

Arsenic and antimony are toxic metalloids and are considered priority environmental pollutants by the U.S. Environmental Protection Agency. Significant advances have been made in understanding microbe-arsenic interactions and how they influence arsenic redox speciation in the environment. However, even the most basic features of how and why a microorganism detects and reacts to antimony remain poorly understood. Previous work with Agrobacterium tumefaciens strain 5A concluded that oxidation of antimonite [Sb(III)] and arsenite [As(III)] required different biochemical pathways. Here, we show with in vivo experiments that a mutation in aioA [encoding the large subunit of As(III) oxidase] reduces the ability to oxidize Sb(III) by approximately one-third relative to the ability of the wild type. Further, in vitro studies with the purified As(III) oxidase from Rhizobium sp. strain NT-26 (AioA shares 94% amino acid sequence identity with AioA of A. tumefaciens) provide direct evidence of Sb(III) oxidation but also show a significantly decreased Vmax compared to that of As(III) oxidation. The aioBA genes encoding As(III) oxidase are induced by As(III) but not by Sb(III), whereas arsR gene expression is induced by both As(III) and Sb(III), suggesting that detection and transcriptional responses for As(III) and Sb(III) differ. While Sb(III) and As(III) are similar with respect to cellular extrusion (ArsB or Acr3) and interaction with ArsR, they differ in the regulatory mechanisms that control the expression of genes encoding the different Ars or Aio activities. In summary, this study documents an enzymatic basis for microbial Sb(III) oxidation, although additional Sb(III) oxidation activity also is apparent in this bacterium.

Publication Information

Output type

Research Output: Contribution to journal Article Peer-review

Original language

English

Pages from-to (Number of pages)

Pages 1959-1965

Journal (Volume, Issue Number)

Applied and Environmental Microbiology (Volume 81, Issue 6)

Publication milestones

  • Accepted/In press - 29/12/2014
  • Published - 29/12/2014

Publication status

Published - 29/12/2014

ISSN

0099-2240

External Publication IDs

  • handle.net: 10547/623439
  • Scopus: 84924665544

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