Dam methylation regulates the expression and secretion of SPI-5-encoded effector sopB in Salmonella enterica serovar Typhimurium

GIACOMODONATO MN; NOTO LLANA, M; AYA CASTAÑEDA MR; BUZZOLA FR; GALLO CALDERÓN M; SARNACKI SH; CERQUETTI, MC

MICROBES AND INFECTION

ELSEVIER SCIENCE BV

Lugar: Amsterdam; Año: 2014

1286-4579

DNA adenine methylation is an essential factor in  Salmonella virulence. Here, we  investigate the involvement of DNA adenine methylase (Dam) in the expression and  translocation of a SPI-5-encoded effector of  S.Typhimurium. SopB expression and  secretion were determined using SopB FLAG-tagged wild type and  damstrains of  S.  Typhimurium. Western blot and quantitative reverse transcriptase PCR analysis showed  that the  dammutant expresses lower levels of SopB protein and  sopBmRNA than the  wild type strain under SPI-1 and SPI-2 inducing conditions in vitro. SopB secretion  was also considerably impaired in the absence of  dam. In agreement with in vitro  experiments, SopB synthesis in  dammutants recovered from infected epithelial cells  and from murine mesenteric lymph nodes was reduced by 40% respect to the wild type  strain (p < 0.05). SopB translocation was neither detected in the cytosol of epithelial  cells nor in the cytosol of cells isolated from mesenteric lymph nodes infected with the dam mutant. Taken together, our results demonstrate that, in  S.  Typhimurium, Dam  methylation modulates the expression and translocation of SPI-5 encoded SopB  effector.