An origin for arsenobetaine involving bacterial formation of an arsenic–carbon bond

Abstract

Lysed-cell extract of a Pseudomonas sp. was shown to catalyse bioconversion of dimethylarsinoylacetate to arsenobetaine and dimethylarsinate. Provision of the universal methyl donor S-adenosylmethionine to bioconversion mixtures promoted both the rate and extent of arsenobetaine formation. These findings suggest that in the proposed biosynthesis of arsenobetaine from dimethy-larsinoylethanol, oxidation (i.e. the formation of the carboxymethyl group of dimethylarsinoylacetate) would precede the reduction and methylation at the arsenic atom. The presence of enzyme(s) capable of methylating dimethylarsinoylacetate in a bacterial isolate from marine mussel (Mylitus edulis), highlights a possible direct involvement of prokaryotic organisms in the biosynthesis of or-ganoarsenic compounds within marine animals.