C H A R A C T E R I Z A T I O N O F R E G U L A T O R Y MECHANISMS OF ShlA HEMOLYSIN EXPRESSION IN Serratia marcescens

STEPANENKO TATIANA MARIEL; DI VENANZIO GISELA ANDREA; CASTELLI MARÍA EUGENIA; GARCÍA VÉSCOVI ELEONORA

Potrero de los Funes

Congreso; 47 Annual Meeting Argentine Society for Biochemistry and Molecular Biology; 2011

Argentine Society for Biochemistry and Molecular Biology

The ShlA hemolysin of Serratia marcescens is one of the major virulence factors of this opportunistic pathogen. ShlA together with ShlB, an outer membrane protein, required for secretion and activation of ShlA, form a two-partner system encoded by the shlBA operon. It has been previously reported that ShlA presents cytotoxic activityinseveral cellular lines, and we have recently demonstrated that it is also responsible for the autophagic phenotype induced by Serratia in epithelial cells. We have also previously determined that the Rcs regulatory system modulates flagellar biogenesis and the expression of the PhlA phospholipase in response to structural alterations in the bacterial envelope. In this work, we analyze the influence of the Rcs phosphorelay system on ShlA synthesis regulation. We found that the rcsB mutant strain presents higher hemolytic activity than the wild type strain, in different growth conditions. This observation is also supported by immunodetection assays, which show higher levels of ShlA in the rcsB mutant. In agreement with this result, we have found a putative RcsB binding site in the promoter region of shlBA operon, suggesting that Rcs system controls shlA expression at the transcriptional level. Together, our results reveal that, in S. marcescens, the Rcs phosphorelay system is key for the regulation of bacterial virulence determinants.