1H, 13C and 15N backbone resonance assignment of the arsenate reductase from Staphylococcus aureus in its reduced state

Abstract

In S. aureus, resistance to the metal(III)oxyanions arsenite As(III)O− 2 and antimonite Sb(III)O− 2 is mediated by two proteins, ArsB and ArsR, encoded in the ars operon of plasmid pI258 (Silver, 1999). ArsR acts as the transcription repressor, which is de-repressed in the presence of intracellular oxy(III)anions (Ji and Silver, 1992). ArsB is an integral membrane protein that functions as an ATP-independent transporter selective for arsenite and antimonite (Bröer et al., 1993). Resistance against arsenate As(V)O3− 4 involves the intervention of the third and final protein coded in the ars operon, ArsC (Chen et al., 1985). This protein reduces intracellular arsenate As(V)O3− 4 to arsenite As(III)O− 2 , which can subsequently be extruded by ArsB. This more elaborate handling of arsenate is thought to avoid phosphate starvation of the bacterium (Silver, 1998).