Linking selenium biogeochemistry to the sulfur-dependent biological detoxification of arsenic |
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Authors: | Couture Raoul-Marie Sekowska Agnieszka Fang Gang Danchin Antoine |
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Affiliation: | Ecohydrology, Department of Earth and Environmental Sciences, University of Waterloo, 200 University Ave W, Waterloo, Canada. |
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Abstract: | 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. |
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