SREL Reprint #3036

Extreme arsenic resistance by the acidophilic archaeon ‘Ferroplasma acidarmanus’ Fer1

Craig Baker-Austin1,6, Mark Dopson1,2, Margaret Wexler1, R. Gary Sawers3, Ann Stemmler4,
Barry P. Rosen4, and Philip L. Bond1,5,7

1School of Biological Sciences, University of East Anglia, Norwich NR4 7TJ, UK
2Molecular Biology, Umeå University, SE-901 87 Umeå, Sweden
3Department of Molecular Biology, John Innes Centre, Norwich NR4 7UH, UK
4Department of Biochemistry and Molecular Biology, Wayne state University, School of Medicine, Detroit, MI 48210, USA
5Centre for Ecology, Evolution and Conservation, University of East Anglia, Norwich NR4 7TJ, UK
6Savannah River Ecology Laboratory, The University of Georgia, Aiken, SC 29802, USA
7Advanced Wastewater Management Centre, University of Queensland, Brisbane 4072 QLD, Australia

Abstract: ‘Ferroplasma acidarmanus’ Fer1 is an arsenic-hypertolerant acidophilic archaeon isolated from the Iron Mountain mine, California; a site characterized by heavy metals contamination. The presence of up to 10 g arsenate per litre [As(V); 133 mM] did not significantly reduce growth yields, whereas between 5 and 10 g arsenite per litre [As(III); 67–133 mM] significantly reduced the yield. Previous bioinformatic analysis indicates that ‘F. acidarmanus’ Fer1 has only two predicted genes involved in arsenic resistance and lacks a recognizable gene for an arsenate reductase. Biochemical analysis suggests that ‘F. acidarmanus’ Fer1 does not reduce arsenate indicating that ‘F. acidarmanus’ Fer1 has an alternative resistance mechanism to arsenate other than reduction to arsenite and efflux. Primer extension analysis of the putative ars transcriptional regulator (arsR) and efflux pump (arsB) demonstrated that these genes are co-transcribed, and expressed in response to arsenite, but not arsenate. Two-dimensional polyacrylamide gel electrophoresis analysis of ‘F. acidarmanus’ Fer1 cells exposed to arsenite revealed enhanced expression of proteins associated with protein refolding, including the thermosome Group II HSP60 family chaperonin and HSP70 DnaK type heat shock proteins. This report represents the first molecular and proteomic study of arsenic resistance in an acidophilic archaeon.

Keywords: Ferroplasma, Arsenic resistance, Arsenite, Proteomics, Primer extension

SREL Reprint #3036

Baker-Austin, C., M. Dopson, M. Wexler, R. G. Sawers, A. Stemmler, B. P. Rosen, and P. L. Bond. 2007. Extreme arsenic resistance by the acidophilic archaeon ‘Ferroplasma acidarmanus’ Fer1. Extremophiles (2007)11:425-434.

This information was provided by the University of Georgia's Savannah River Ecology Laboratory (srel.uga.edu).