PmrA and RcsB expression is affected by Dam methylation in Salmonella Enteritidis

M.DEL ROSARIO AYA C; SEBASTIÁN SARNACKI; MARIÁNGELES NOTO LLANA; MÓNICA GIACOMODONATO; MIGUEL VALVANO; MARÍA CRISTINA CERQUETTI

Portero de Funes, San Luis

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

Sociedad Argentina de Investigación Bioquímica y Biología Molecular (SAIB)

We reported earlier that S. Enteritidis dam mutant, has a partial defect in the O Ag chain length distribution, possibly due to a reduced expression of rcsB, one of the two regulators of wzz, together with pmrA. Here we show, not only that pmrA is also regulated by Dam methylation, but that a compensatory effect would exist between both wzz regulators. We investigated the PmrA protein expression in the dam mutant. PmrA was tagged adding a 3xFLAG. The expression was analysed by Western blot. Similar PmrA expression was found in dam mutant and in wt strain. However, the expression of pmrA studied by RT-PCR showed reduced levels of mRNA in the dam mutant. Next we studied the expression of wzz in pmrA and rcsB mutants. Results showed that in the absence of rcsB, the amount of wzz mRNA was reduced in 50% compared with the wt. Surprisingly, in pmrA mutant the amount of wzz mRNA was 30% higher than in the wt. In order to investigate the putative interaction between both wzz regulators, we determined the expression of rcsB in a pmrA mutant and pmrA expression in a rcsB mutant. We found that in rcsB mutant the expression of pmrA mRNA decreases 40%, whereas in the absence of pmrA, rcsB mRNA increases 10%, suggesting a compensatory effect. Thus, in S. Enteritidis Dam regulates Wzzthrough its two regulators, PmrA and RcsB; a compensatory mechanism would exist between both regulators.