Gold resistance in Salmonella typhimurium

ESPARIZ, M.; PÉREZ AUDERO, M. E.; BOTTA, P.; SUSANA KARINA CHECA; SONCINI, F. C.

Iguazú

Congreso; Argentine Society for Biochemistry and Molecular Biology XL Annual Meeting. Protein Phosphorylation and Bioregulation Symposium.; 2004

Sociedad Argentina de Investigación en Bioquímica y Biología Molecular

GOLD RESISTANCE IN Salmonella typhimurium. Espariz, Martín; Pérez Audero, María E.; Botta Pablo E.;;  Checa, Susana K.; and Soncini, Fernando C. IBR-CONICET, Fac.  Cs. Bioquímicas y Farmaceúticas,  Rosario, Argentina. E-mail: martinespariz@yahoo.com.ar Salmonella species have evolved to survive in a wide range of environments such as food, water or the human being. The aim of our work is to contribute to understand this complex phenomena. From an in silico searching of new transcriptional regulators, we identified a Salmonella specific MerR-like regulator that showed to be induced in the presence of gold salts. This regulator control the expression of a putative P-type ATPase (hmrT) and a small metal binding protein (hmrB). In order to investigated the biological function of this system, we test the sensitivity to gold salts of mutants in these genes. We found that hmrR mutants were more sensitive to this metal than wild type bacteria. Mutants in either, hmrT or hmrB, or both showed an intermediate tolerance suggesting that other HmrR-contoled genes are required for full tolerance. In an attempt to identified new genes involved in gold tolerance in Salmonella we determined the survival of mutants in several putative cation efflux systems. This analysis indicated that mutants in E. coli homologs to copper efflux systems, cusBAC and copA, were also more sensitive to gold than wild type bacteria. However, the expression of these loci was not dependent of the gold content suggesting that these systems act in an unspecific way. In summary, we proved that Salmonella has acquired genes that enable it to grow in the presence of heavy metal and that HmrR is an essential regulator for gold tolerance.