title: The ompW (porin) gene mediates methyl viologen (paraquat) efflux in Salmonella enterica serovar typhimurium.
abstract: Porins are channels that enable passive diffusion of hydrophilic solutes, nutrients and toxins through the outer bacterial membrane. This explains in part the ability of Gram-negative microorganisms to grow in several different environments, as well as their drug resistance. OmpD is an outer membrane channel that works with the inner membrane pump YddG to expel methyl viologen (MV) from Salmonella enterica serovar Typhimurium; this occurs independently of SmvA, also involved in MV resistance. On the other hand, DeltatolC strains show increased MV resistance when compared to wild-type cells, suggesting that there may be other porin(s) that could function with SmvA to pump MV out of S. typhimurium. A strong candidate is OmpW. Here we show that DeltaompW strains of S. typhimurium are 2.5-fold more sensitive to MV than the wild-type strain. Transcriptional fusions replacing ompW by lacZ show that ompW is induced at least 2-fold in the presence of MV. This result was observed both at the mRNA and protein levels, suggesting that ompW participates in MV resistance. In addition, DeltasmvADeltaompW strains are not fully complemented by smvA, suggesting that OmpW may function through an independent pathway different from that used by SmvA to move MV outside the cell.
authors.affiliation: Laboratorio de Microbiología Molecular, Facultad de Ciencias de la Salud, Universidad Andrés Bello, Santiago, Chile. f.gil@uandresbello.edu
authors.forename: Fernando
authors.initials: F
authors.lastname: Gil
authors.forename: Francisco
authors.initials: F
authors.lastname: Ipinza
authors.forename: Juan
authors.initials: J
authors.lastname: Fuentes
authors.forename: Robinson
authors.initials: R
authors.lastname: Fumeron
authors.forename: José M
authors.initials: JM
authors.lastname: Villarreal
authors.forename: Alexis
authors.initials: A
authors.lastname: Aspée
authors.forename: Guido C
authors.initials: GC
authors.lastname: Mora
authors.forename: Claudio C
authors.initials: CC
authors.lastname: Vásquez
authors.forename: Claudia
authors.initials: C
authors.lastname: Saavedra
mesh_terms: D001425:Bacterial Outer Membrane Proteins / Q000235:genetics*; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D001483:Base Sequence; D001692:Biological Transport; D024881:Drug Resistance, Bacterial; D007700:Kinetics; D008969:Molecular Sequence Data; D016296:Mutagenesis; D010269:Paraquat / Q000493:pharmacokinetics*; D016133:Polymerase Chain Reaction; D018272:Porins / Q000235:genetics*; D012329:RNA, Bacterial / Q000235:genetics; D012333:RNA, Messenger / Q000235:genetics; D012486:Salmonella typhimurium / Q000235:genetics*; D017384:Sequence Deletion; D001616:beta-Galactosidase / Q000378:metabolism
chemical_list: D001425:Bacterial Outer Membrane Proteins; D001426:Bacterial Proteins; D018272:Porins; D012329:RNA, Bacterial; D012333:RNA, Messenger; D001616:beta-Galactosidase; D010269:Paraquat