Transcriptional control of the copper-resistance regulon in Salmonella enterica

PEZZA, A.; PONTEL, L. B.; SONCINI, F. C.

Potrero de los Funes, San Luis

Congreso; XLVII Reunión Anual; 2011

Sociedad Argentina de Investigación en Bioquímica y Biología Molecular

Copper (Cu) is an essential metal required as a cofactor in numerous essential biochemical reactions. However, free Cu ions can be toxic. In Gram-negative bacteria, Cu toxicity is handled by the cue regulon. This includes the Cu-sensor/regulator CueR that induces the expression of the Cu-efflux pump copA and the multicopper oxidase cueO coding genes. Under anaerobic conditions most species also require the cus system to cope with Cu excess. This includes CusR/CusS, a two-component system that senses periplasmic Cu and induces the expression of CusCFBA, an RND-based Cu-efflux pump. In Salmonella as well as in other species that do not harbor the cus locus, Cu resistance in anaerobiosis relies on CueP, a periplasmic protein encoded by a gene that belongs to the Salmonella cue regulon. We examined the transcriptional regulation of the Salmonella cue regulon in different environments and found a differential expression within its constituents. Using bioinformatic tools we detected putative cis-acting sequences responsible for this differential expression. in vivo transcription as well as in vitro footprinting experiments allowed us to confirm the existence of these regulatory elements, which ensure the correct supply of the copper-resistance components when the environment becomes unfavorable for cell survival.