Fighting copper: The Salmonella specific resistance.

PONTEL,L.B., ESPARIA,M., SONCINI,F.C.

Rosario, Argentina

Congreso; XLII Reunion Anual Sociedad Argentina de Investigación en Bioquímica y Biología Molecular; 2006

SAIB

Copper ions represent a dual challenge for both prokaryotic and eukaryotic cells. They are required for the proper function of several enzymes but can also catalyze 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 organism, 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 in Salmonella 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 the level of copper ions. These results show that Salmonella has evolved this specific system to survive in toxic copper environments.