REGULATION OF THE TYPE VI SECRETION SYSTEM OF Serratia marcescens: THE ROLE OF THE Rcs SYSTEM

LAZZARO, M; GARCÍA VÉSCOVI, E.

Mar del Plata

Congreso; LI Reunión Anual Sociedad Argentina de Investigación en Bioquímica y Biología Molecular; 2015

Sociedad Argentina de Investigación en Bioquímica y Biología Molecular

Serratia marcescens is an opportunistic human pathogen that represents a growing problem for public health. It hasbeen previously reported that the type VI secretion system (T6SS) of S. marcescens has a role in bacterialcompetition. This characteristic may provide an important competitive advantage against other bacteria in the host orin environmental niches. However, little is known about its regulation. In this work, we analyze the regulation of theT6SS of S. marcescens. We propose that this system is regulated by the Rcs system. We found that the rcsB mutantstrain shows a lower antibacterial activity than the wild type strain. This observation is also supported byimmunodetection assays, which shows lower levels of Hcp (a structural component of the T6SS) in the rcsB mutant. In addition, we have found a putative RcsB binding site in the promoter region of the cluster that codes for the components of T6SS. Using a fusion to GFP as a reporter of the transcriptional activity of that promoter, we have determined that the level of transcriptional activity in the rcsB mutant strain is lower than in the wild type strain. In agreement with this result, we have done real-time PCR assays and we have found that the level of transcript of T6SS is lower in the rcsB mutant. Together, our results show that, in S. marcescens, the Rcs system regulates the T6SS at the transcriptional level.