Cupriavidus metallidurans strain CH34 is a multiple metal resistant -proteobacterium isolated from the sediments of a zinc metallurgical plant. This strain possesses a large diversity of heavy metal resistance genes that are located mostly on two large plasmids, pMOL28 and pMOL30. The metal efflux ATPases constitute the major mechanism by which metal ions are removed and pumped out from the cytoplasmic pool of thiol groups. The genome of C. metallidurans CH34 contains eight such P1-ATPases. This high number of ATPases, compared to the P1-ATPase content in other microorganisms, is a typical feature of the adaptation of C. metallidurans CH34 to metal-rich biotopes. We performed phylogenetic analysis, and used quantitative PCR to study the metal specific induction of the ATPases genes and, for some of them, their neighbouring genes. One of the ATPases, a homologue of the E. coli zntA gene, was characterized in detail, by analyzing the phenotypes of zntA mutants in different genetic backgrounds. In addition to the already reported sensitivity to Zn(II), Cd(II) and Pb(II), zntA mutants also displayed a higher sensitivity to Tl(I) and Bi(III), indicating that the ZntA protein might play role in the tolerance of very large cations.
|Journal||International Journal of Environmental Analytical Chemistry|
|State||Published - 10 Aug 2006|