REGULATION OF EXPRESSION OF THE TWO-COMPONENT SYSTEM CitST IN Bacillus subtilis

SENDER, PD; BLANCATO, VS; LOLKEMA, J; MAGNI, C

San Carlos de Bariloche (Río Negro)

Congreso; XXXIX Reunión Anual de SAIB; 2003

Sociedad Argentina de Investigación en Bioquímica y Biología Molecular

The two-component signal transduction system is a ubiquitous mechanism for sensing and responding to several environmental stimuli in bacteria. In Bacillus subtilis, citS and citT encode a two-component system involved at the regulation of the citrate transporter CitM. Induction of citM is mediated by CitS (sensor kinase), which recognizes external citrate, and CitT (response regulator) that work as a transcriptional activator by binding to the promoter region of citM. Due to the expression of citM depends on the expression of the two-component citS and citT, in this period we start the molecular characterization of the gene expression of this two-component system to understand more about the exquisite regulation in the citrate-Mg+2 transport in B. subtilis. Our experiments shown that an expression of the two-component system depends on the constitutive promoter located upstream region of  citS. The control of the citS expression is under the CcpA protein, which binds to the cre site present in the internal region of this gene. The expression of citST is not repressed by arginine in rich medium suggesting that this repression is operated in the citM region.