Regulation of the O-antigen synthesis in Salmonella enterica serovar Typhimurium and their application in the attenuate vaccines development.

ESTELA CERASUOLO; ROBERTO MORERO; MONICA DELGADO

San Pablo-Brasil

Congreso; 8a Feria Iberoamericana de Biotecnología 2008 y 4º Congreso Brasileño de Biotecnología; 2008

Biolatina

Regulation of the O-antigen synthesis in Salmonella enterica serovar Typhimurium and their application in the attenuate vaccines development ESTELA CERASUOLO, ROBERTO MORERO AND MONICA DELGADO Microorganisms respond to changing environmental conditions regulating the genes expression via two-component systems. The PmrA/PmrB system consists of the response regulator PmrA, that is activated by Fe3+, which is the signal sensed by its sensor PmrB, and by low Mg2+, in a pathway that requires the Mg2+-responsive PhoP/PhoQ system. To date, all the characterized PmrA-regulated genes participate in the LPS modification, and are necessary for resistance to polymyxin B and to serum complement. Previously, has been demonstrated the wzzfepE gene controls the amount of O-antigen very long chain in the LPS (35 to 100 O-antigen subunits), but we demonstrated that can not modify the resistance to the serum complement-mediated killing. Nevertheless, we had demonstrated that the absence of pbgE2E3 and wzzst genes, induced by the PmrA/PmrB system, resulted in an O-antigen without the region containing 1 to 15 or 16 to 35 O-antigen subunits and decrease the sensitivity to serum complement. These results indicated that the PmrA/PmrB system is the master regulator of the LPS synthesis and that both, O-antigen formation and the lipid A modification, are required at the same time during the Salmonella infection.