NEW INSIGHTS INTO THE CONTROL OF MAGNESIUM HOMEOSTASIS IN Salmonella enterica

SPINELLI, S.V.; PONTEL, L.B.; GARCÍA VÉSCOVI, E.; SONCINI, F.C.

Bariloche, Argentina

Congreso; XXXIX Reunión anual de la Sociedad Argentina de Investigaciones en Bioquímica y Biología Molecular; 2003

Sociedad Argentina de Investigaciones en Bioquímica y Biología Molecular

Magnesium plays a fundamental role in Salmonella pathogenesis. It controls the activation of the PhoP/PhoQ regulatory system, signaling the bacteria its specific location inside the host. In response to Mg2+ limitation, the PhoP/PhoQ regulatory system triggers the expression of two high-affinity Mg2+ transporter genes, mgtA and mgtCB. Mutations in mgtA or in mgtCB greatly affect the ability of Salmonella to grow in low Mg2+ environments.  We uncovered a novel checkpoint in the Mg2+ deprivation response. This mechanism can detect this cellular stress bypassing PhoQ and posing an additional control over the expression of the Mg2+ transporters. We have demonstrated that in mgtA the responsive element for the PhoQ-independent regulatory mechanism maps to the 5’UTR. We further characterized this region using site directed mutagenesis, and examined the level (transcriptional/ posttranscriptional) at which this system exerts its control. The study of this homeostatic network will provide new insights in the mechanisms that allow Salmonella to proliferate within its host.