Gold resistance in Salmonella typhimurium

ESPARIZ, MARTÍN; PÉREZ AUDERO, MARÍA EUGENIA; BOTTA, PABLO; CHECA, SUSANA KARINA; SONCINI, FERNANDO CARLOS

Puerto Iguazú - Misiones

Congreso; XXXX Reunión anual de la Sociedad de Investigación en Bioquímica y Biología Molecular; 2004

Sociedad de Investigación en Bioquímica y Biología Molecular

We have screened the Salmonella genome for loci encoding Salmonella-specific metal-responsive MerR homologues. Among the genes detected, we have identified one that we termed godS. GodS controls the expression of two transcriptional units, godTS and godB, in response to gold salts. These genes code for a P-type ATPase with homology to metal transporters, the regulator, and a metal-binding protein, respectively. We investigated the role of this regulon in the resistance to gold and other heavy metals salts.  We found that a mutant strain deleted in godS was more susceptible only to gold salts than the wild type. Mutants in either godT or godB or in both genes showed an intermediate tolerance, suggesting that other GodS-controlled genes are required for full tolerance. We analyzed a series of putative cation efflux systems in order to identify additional genes involved in gold tolerance. Mutants in the copper efflux systems cusBAC and copA were more sensitive to gold than the wild type. However, the expression of these loci was not modulated by gold suggesting that these systems are not controlled by the God regulon. In sum, to our knowledge this is the first gold-specific detoxification system horizontally acquired into the Salmonella genome, that allow this pathogenic bacterium to monitor and to resist environments with high concentration of gold salts.