Genetic and Physiological Analysis of the Salmonella copper response

ESPARIZ, M.; PÉREZ AUDERO, M. E.; PONTEL, L. B.; SUSANA KARINA CHECA; SONCINI, F. C.

Rosario

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

Sociedad Argentina de Investigación en Bioquímica y Biología Molecular

Copper is an essential trace metal element for both eukaryotes and prokaryotes. It is associated with several metal enzymes, which are involved in electron transport, reduction of nitrite and nitrous oxides, and electron carriers. Intracellular copper homeostasis results from a very complex ensemble and interaction of a number of cellular processes. We have undertaken an in vivo characterization of the extracellular copper response in the pathogenic enterobacterium Salmonella typhimurium. This bacterium harbours all the components of the cytoplasmic/periplasmic-copper controlling CueR system, including the MerR-like regulator CueR, and the multicopper oxidase CueO. It also harbours a gene coding for a P-type ATPase responsible for copper transport, copA, which we demonstrate to be under direct CueR regulation. Surprisingly, no homologous system to CusR/CusS or its target operon, cusCFBA, could be identified in the Salmonella genome. Furthermore, Salmonella harbours a second CueR-homologous transcriptional regulator that is highly sensitive to gold ions, GodS, which induces the expression of a CopA-homologous protein, GodT. We provide evidences that, in the absence of a functional CopA, GodS induces the expression of GodT, which can substitute for the ancestral copper-transporter for metalresistance.