A probable link between the DedA protein and resistance to selenite

Abstract

To understand the molecular events involved in the reduction of selenite to non-toxic elemental selenium, 4000 clones of Ralstonia metallidurans CH34 were produced by random Tn 5 transposon integration mutagenesis. Eight mutants were able to resist up to 15 mM selenite while the MIC for the wild-type strain was estimated as 4–6 mM selenite. The identification of the disrupted genes was carried out by Southern blot analysis and inverse PCR. The three resistant mutants containing only one insertion were further characterized. Tn 5 disrupted a gene that encoded a protein which was closely related to proteins of the DedA family. This family represents a group of integral membrane proteins with completely unknown functions. Phenotypic characterization of the dedA mutants and selenite consumption experiments strongly suggest that DedA is involved in the uptake of selenite.