Extremophiles

, Volume 7, Issue 2, pp 123–130

Arsenic resistance in the archaeon "Ferroplasma acidarmanus": new insights into the structure and evolution of the ars genes

  • Thomas M. Gihring
  • Philip L. Bond
  • Stephen C. Peters
  • Jillian F. Banfield
Original Paper
  • 202 Downloads

Abstract

Arsenic resistance in the acidophilic iron-oxidizing archaeon "Ferroplasma acidarmanus" was investigated. F. acidarmanus is native to arsenic-rich environments, and culturing experiments confirm a high level of resistance to both arsenite and arsenate. Analyses of the complete genome revealed protein-encoding regions related to known arsenic-resistance genes. Genes encoding for ArsR (arsenite-sensitive regulator) and ArsB (arsenite-efflux pump) homologues were found located on a single operon. A gene encoding for an ArsA relative (anion-translocating ATPase) located apart from the arsRB operon was also identified. Arsenate-resistance genes encoding for proteins homologous to the arsenate reductase ArsC and the phosphate-specific transporter Pst were not found, indicating that additional unknown arsenic-resistance genes exist for arsenate tolerance. Phylogenetic analyses of ArsA-related proteins suggest separate evolutionary lines for these proteins and offer new insights into the formation of the arsA gene. The ArsB-homologous protein of F. acidarmanus had a high degree of similarity to known ArsB proteins. An evolutionary analysis of ArsB homologues across a number of species indicated a clear relationship in close agreement with 16S rRNA evolutionary lines. These results support a hypothesis of arsenic resistance developing early in the evolution of life.

Keywords

Arsenic Resistance ars Ferroplasma acidarmanus Acidophile Evolution Phylogeny Genomics 

Copyright information

© Springer-Verlag 2003

Authors and Affiliations

  • Thomas M. Gihring
    • 1
    • 6
  • Philip L. Bond
    • 2
  • Stephen C. Peters
    • 3
    • 7
  • Jillian F. Banfield
    • 4
    • 5
  1. 1.Department of Geology and GeophysicsThe University of Wisconsin MadisonMadisonUSA
  2. 2.School of Biological SciencesUniversity of East AngliaNorwichUK
  3. 3.Department of Geological SciencesThe University of MichiganAnn ArborUSA
  4. 4.Department of Geology and GeophysicsThe University of Wisconsin MadisonMadisonUSA
  5. 5.Department of Earth and Planetary SciencesUniversity of California BerkeleyBerkeleyUSA
  6. 6.Pacific Northwest National LaboratoryMS P7-50RichlandUSA
  7. 7.Department of Earth and Environmental SciencesLehigh UniversityBethlehemUSA

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