Serratia marcescens ShlA hemolysin is inhibited by Ni2+

LAZZARO, M.; GARCÍA VÉSCOVI, E.

Paraná, Entre Ríos

Congreso; LIV Reunión de la Sociedad Argentina de Investigación Bioquímica y Biología Molecular (SAIB); 2018

SAIB

Serratia marcescens is an opportunistic human pathogen that represents a growing problem forpublic health. We have previously reported that S. marcescens is able to invade, survive and proliferate innon-phagocytic cells. After proliferation, the ShlA hemolysin is responsiblefor an increase in the cytosolic Ca2+ concentration, remodeling theactin cytoskeleton and promoting an exocytic-like egress. It has been reportedthat ShlA is necessary for cytotoxicity in different cells lines. At sub-lyticconcentrations, it induces ATP depletion and K+ efflux. The aim of this work is to find tools that allow us to understand thefunction of ShlA. Performing invasionassays, co-localization with a calcium fluorophore and autophagy assays, wedetermined that in presence of Ni2+ wild-type Serratia behavies like a shlBAmutant. These assays were done in sub-lytic conditions and are also blockedby the addition of the calcium chelator BAPTA-AM. Next, we performed hemolytic and cytotoxicity assays and we determined thatthe addition of Ni2+ to the wild-type strain blocked the lysis ofthe eukaryotic cells, obtaining a phenotype similar to the observed in the shlBA mutant. The addition of BAPTA-AMdid not block the eukaryotic cells lysis. We conclude that in presence of Ni2+ wild-type Serratia behavies like a shlBA mutant both in lytic and innon-lytic conditions. Moreover, we hypothesize that ShlA is responsible for twodifferent types of phenotypes. The lytics phenotypes are independent of theintracellular concentration of calcium. In contrast, the ones that are induced insub-lytic conditions of ShlA are dependent of a Ca2+ mobilization.