title: The PhoP/PhoQ system and its role in Serratia marcescens pathogenesis.
abstract: Serratia marcescens is able to invade, persist, and multiply inside nonphagocytic cells, residing in nonacidic, nondegradative, autophagosome-like vacuoles. In this work, we have examined the physiological role of the PhoP/PhoQ system and its function in the control of critical virulence phenotypes in S. marcescens. We have demonstrated the involvement of the PhoP/PhoQ system in the adaptation of this bacterium to growth on scarce environmental Mg(2+), at acidic pH, and in the presence of polymyxin B. We have also shown that these environmental conditions constitute signals that activate the PhoP/PhoQ system. We have found that the two S. marcescens mgtE orthologs present a conserved PhoP-binding motif and demonstrated that mgtE1 expression is PhoP dependent, reinforcing the importance of PhoP control in magnesium homeostasis. Finally, we have demonstrated that phoP expression is activated intracellularly and that a phoP mutant strain is defective in survival inside epithelial cells. We have shown that the Serratia PhoP/PhoQ system is involved in prevention of the delivery to degradative/acidic compartments.
authors.affiliation: Instituto de Biología Molecular y Celular de Rosario (IBR-CONICET), Departamento de Microbiología, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Rosario, Argentina.
authors.forename: Julieta
authors.initials: J
authors.lastname: Barchiesi
authors.forename: María Eugenia
authors.initials: ME
authors.lastname: Castelli
authors.forename: Gisela
authors.initials: G
authors.lastname: Di Venanzio
authors.forename: María Isabel
authors.initials: MI
authors.lastname: Colombo
authors.forename: Eleonora
authors.initials: E
authors.lastname: García Véscovi
mesh_terms: D000143:Acids / Q000378:metabolism; D000595:Amino Acid Sequence; D000818:Animals; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D001483:Base Sequence; D002460:Cell Line; D015964:Gene Expression Regulation, Bacterial; D006801:Humans; D008247:Lysosomes / Q000378:metabolism / Q000382:microbiology; D008274:Magnesium / Q000378:metabolism; D050296:Microbial Viability; D008969:Molecular Sequence Data; D016415:Sequence Alignment; D016868:Serratia Infections / Q000382:microbiology*; D012706:Serratia marcescens / Q000235:genetics / Q000254:growth & development / Q000378:metabolism* / Q000472:pathogenicity*; D014774:Virulence
chemical_list: D000143:Acids; D001426:Bacterial Proteins; C079792:PhoQ protein, Bacteria; C061064:PhoP protein, Bacteria; D008274:Magnesium