NreB from Achromobacter xylosoxidans 31A is a nickel-induced transporter conferring nickel resistance

There are two distinct nickel resistance loci on plasmid pTOM9 from Achromobacter xylosoxidans 31A, ncc and nre. Expression of the nreB gene was specifically induced by nickel and conferred nickel resistance on both A. xylosoxidans 31A and Escherichia coli. E. coli cells expressing nreB showed reduced accumulation of Ni2+, suggesting that NreB mediated nickel efflux. The histidine-rich C-terminal region of NreB mas not essential but contributed to maximal Ni2+ resistance.