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Environmental Microbiology
Vol. xx, No: xx, 2012, Pages: xxx - xxx

Linking selenium biogeochemistry to the sulfur-dependent biological detoxification of arsenic

Couture RM, Sekowska A, Fang G, Danchin A

Ecohydrology, Department of Earth and Environmental Sciences, University of Waterloo, 200 University Ave W, Waterloo, Canada N2L 3G1 AMAbiotics SAS, Bâtiment G1, 2 rue Gaston Crémieux, 91000 Evry, France Department of Molecular Biophysics & Biochemistry, Medical School, Yale University New Haven, CT 06520, USA Department of Biochemistry, Faculty of Medicine, Hong Kong University, 21 Sassoon Road, Pokfulam, Hong Kong.


Geochemistry often reveals unexpected (anti)correlations. Arsenic (As) and selenium (Se) are cases in point. We explore the hypothesis that bacteria living in an As-replete environment recruited a biological process involving Se and sulfur to fulfil their need for As detoxification. In analogy with the formation of arsenolipids and arsenosugars, which are common non-toxic As metabolites derived from microbial and plant metabolism, we attempt to explain the prevalence of novel sulfur-containing As derivatives, in particular monothioarsenate, in the aqueous environment. Thiolated-As species have been overlooked so far mainly because of the difficulty of their identification. Based on comparative genomics, we propose a scenario where SelD and SelU proteins, commonly used to make selenophosphate and modify transfer RNA, have been recruited to make monothioarsenate, a relatively innocuous arsenical. This hypothesis is discussed in terms of the relative geochemical distribution of Se and As.

Keywords:Geochemistry often reveals unexpected (anti)correlations,Arsenic (As) and selenium (Se),geochemical distribution of Se and As.


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