Characterization of new Listeria monocytogenes surface proteins of the LPXTG family

JAVIER FERNANDO MARISCOTTI; ENRIQUE CALVO; LAURA BOTELLO-MORTE; M. GRACIELA PUCCIARELLI; FRANCISCO GARCÍA-DEL PORTILLO

Tenerife

Congreso; ERA-NET PathoGenoMics 2010; 2010

ERA-NET PathoGenoMics

Listeria monocytogenes is a Gram-positive bacteria pathogen that causes listeriosis, a severe food-borne disease in humans. This bacterium has the ability of cross three host barriers during infection: the intestinal, the blood-brain, and the feto-placental barriers. L. monocytogenes also invades phagocytic and non-phagocytic host cell types in which it survives or proliferates. The genome of L. monocytogenes encodes 41 proteins that are anchored covalently to the peptidoglycan via the recognition by a sole enzyme, the sortase SrtA, of a conserved LPXTG motif located in the C-terminus. These surface proteins are candidates to play an important role in the host-pathogen interaction. Some of the few proteins of this family characterized at the functional level include the invasins Internalin-A (InlA), and Vip; together with InlJ, which promotes adhesion. The role of the rest of LPXTG proteins remains unknown. The goal of our study was to characterize six LPXTG proteins of Listeria monocytogenes in the context of the current ERA-NET project named SPATELIS, which addresses the biology of the entire LPXTG protein family. We constructed six defective mutants in the following LPXTG surface proteins: Lmo0159, Lmo0160, Lmo0550, Lmo0725, Lmo2178 and Lmo2179, which were further subjected to phenotypic analyses. These mutants did not exhibit differences in invasion and intracellular proliferation in human cultured epithelial cells JEG-3. Using specific antibodies, we detected two of these proteins, Lmo0159 and Lmo0160, in the cell wall of L. monocytogenes grown in brain-heart infusion (BHI) medium and in intracellular bacteria growing inside epithelial cells. We also analyzed the cell wall proteome in these mutants to assess putative differences in the content of other LPXTG proteins. No significant differences were found in the relative amount of other LPXTG proteins. Future goals include the virulence analysis of these mutants in BALB/c model and the identification of putative host ligands involved.