Fighting copper: The Salmonella specific resistance.

LUCAS B. PONTEL; MARTÍN ESPARIZ; FERNANDO C. SONCINI

Rosario, Santa Fe, Argentina.

Congreso; 42th Annual Meeting of Argentine Society for Biochemistry and Molecular Biology (SAIB).; 2006

Sociedad Argentina de Bioquímica y Biología Molecular.

Copper ions represent a dual challenge for both prokaryotic and eukaryotic cells. It is required for the proper function of several enzymes but can also catalyse harmful redox reactions resulting in cell damage. Cellular systems must respond to changes in the extracellular bioavailability of this element over a wide and dynamic concentration range. Escherichia coli, one of the best studied organisms, harbours three systems involved in copper resistance: the ATPase efflux protein CopA, the periplasmic multicopper oxidase CueO, and the multicomplex system CusCFBA. We investigated the presence of similar systems in the pathogenic bacterium Salmonella enterica serovar Typhimurium. Although, copA and cueO ortholog genes are encoded in the bacterial genome, no homolog system to CusCFBA could be found, suggesting that Salmonella employs a different mechanism to cope with the metal ion excess. We performed a genomic screening searching for genes involved in copper resistance. We identified a protein that we named CueP, involved in copper resistance both in anaerobic conditions and in environments where CueO is not active. We established that cueP expression is controlled by copper ions level in the surrounding media. These results show that Salmonella has evolved specific systems to survive in toxic copper environments.