IMPAIRED EXPRESSION AND SECRETION OF SOPB, SOPD AND SOPE2 IN SALMONELLA DAM MUTANTS

GIACOMODONATO MN, ; GARTNER AS, ; GARCIA BLATZ MD, ; SARNACKI SH, ; NOTO LLANA M, ; CERQUETTI MC.

San Luis

Congreso; XLVII Reunión Anual de la Sociedad Argentina de Investigación en Bioquímica y Biología Molecular; 2011

SAIB

Dam methylation is an essential factor involved in the virulence of an increasing number of bacterial pathogens including Salmonella spp. dam mutants have a reduced capacity to colonize murine organs compared to the parental strain. This partial inability could be related to a reduced secretion of invasion proteins. Then, we investigated the involvement of Dam methylation on the expression and secretion of essential proteins for invasion, such as SopB, SopD and SopE2. These effectors are located outside of SPI-1 but are translocated in a SPI-1-dependent manner. S. Typhimurium sopB, sopD and sopE2 tagged (3xFLAG) strains and their derivative Ädam were used during the experiments. The expression and secretion of these effectors were determined in vitro, under SPI-1 culture conditions, analyzing bacterial pellets and culture supernatants, respectively. Tagged proteins were examined by SDS-page and immunoblotting with anti-FLAG antibodies. Western blot results showed an impaired SopB, SopD and SopE2 expression and secretion in dam mutants with respect to the parental strain (p < 0.05). These results were further confirmed by QRT-PCR showing that sopB, sopD and sopE2 genes transcription were two or three-fold lower in dam mutants compared to wild type strain. Taken together, our results demonstrate that Dam methylation modulates the expression and secretion of SopB, SopD and SopE2.