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Characterization of a two-component signal transduction system that controls arsenite oxidation in the chemolithoautotroph NT-26

  • Tom Osborne
    ,
  • Sunita Sardiwal
    ,
  • Joanne M. Santini
    ,
  • Thomas H. Osborne
    ,
  • Snezana Djordjevic
  • University College London
Research Output: Contribution to journal Article Peer-review

Abstract

NT-26 is a chemolithoautotrophic arsenite oxidizer. Understanding the mechanisms of arsenite signalling, tolerance and oxidation by NT-26 will have significant implications for its use in bioremediation and arsenite sensing. We have identified the histidine kinase (AroS) and the cognate response regulator (AroR) involved in the arsenite-dependent transcriptional regulation of the arsenite oxidase aroBA operon. AroS contains a single periplasmic sensory domain that is linked through transmembrane helices to the HAMP domain that transmits the signal to the kinase core of the protein. AroR belongs to a family of AAA+ transcription regulators that interact with DNA through a helix-turn-helix domain. The presence of the AAA+ domain as well as the RNA polymerase σ(54) -interaction sequence motif suggests that this protein regulates transcription through interaction with RNA polymerase in a σ(54) -dependent fashion. The kinase core of AroS and the receiver domain of AroR were heterologously expressed and purified and their autophosphorylation and transphosphorylation activities were confirmed. Using site-directed mutagenesis, we have identified the phosphorylation sites on both proteins. Mutational analysis in NT-26 confirmed that both proteins are essential for arsenite oxidation and the AroS mutant affected growth with arsenite, also implicating it in the regulation of arsenite tolerance. Lastly, arsenite sensing does not appear to involve thiol chemistry.

Publication Information

Output type

Research Output: Contribution to journal Article Peer-review

Original language

English

Pages from-to (Number of pages)

Pages 20-28

Journal (Volume, Issue Number)

FEMS Microbiology Letters (Volume 313, Issue 1)

Publication milestones

  • Accepted/In press - 01/09/2010
  • Published - 07/10/2010

Publication status

Published - 07/10/2010

ISSN

0378-1097

External Publication IDs

  • handle.net: 10547/623438
  • Scopus: 78349291126

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