THE PHOP/PHOQ SYSTEM AND MGTES GENES ROLE IN Serratia marcescens PATHOGENESIS

DI VENANZIO, GISELA; LESTRADET, MATTHIEU; FERRANDON, DOMINIQUE; GARCÍA VÉSCOVI, ELEONORA

Rosario

Congreso; Sociedad Argentina de Investigación en Bioquímica y Biología; 2015

Sociedad Argentina de Investigación en Bioquímica y Biología Molecular

The S. marcescens PhoP/PhoQ system is involved in the adaptation of this bacterium to growth on scarce environmental Mg2+, at acidic pH, and in the presence of polymyxin B. As we previously reported, there are two mgtE orthologs in Serratia that present a conserved PhoP-binding motif. mgtE1 expression had been shown to be PhoP dependent and is required for optimal growth under Mg2+ limiting conditions. To asses mgtE2 transcriptional regulation we constructed lacZ- and gfp-containing reporter plasmids. Regarding to their role in pathogenesis, we determined that a phoP mutant strain is defective in survival inside epithelial cells and that the PhoP/PhoQ system is involved in prevention of the delivery to degradative/acidic compartments. In D. melanogaster, a phoP mutant strain was unable to kill A5001 and Eater Drosophila mutants in a septic injury model, but regained full virulence in a Key mutant background. However, the phoP mutant was capable of damaging the insect gut in the early phase of the oral infection model. In CHO cells, the mgtEs mutants were unable to survive at late times p.i. and co-localized with acidic compartments. Based on these findings, we propose that a) the PhoP/PhoQ system is involved in the resistance to AMPs in D. melanogaster, and b) the mgtEs genes could be involved in reventing the delivery to degradative/acidic compartments.