The ompW (porin) gene mediates methyl viologen (paraquat) efflux in Salmonella enterica serovar Typhimurium

Fernando Gil, Francisco Ipinza, Juan Fuentes, Robinson Fumeron, José M. Villarreal, Alexis Aspée, Guido C. Mora, Claudio C. Vásquez, Claudia Saavedra

Research output: Contribution to journalArticlepeer-review

55 Citations (Scopus)


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, ΔtolC 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 ΔompW 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, ΔsmvAΔompW 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.

Original languageEnglish
Pages (from-to)529-536
Number of pages8
JournalResearch in Microbiology
Issue number6
Publication statusPublished - Jul 2007


  • Methyl viologen
  • OmpW
  • Porin
  • Salmonella typhimurium

ASJC Scopus subject areas

  • Microbiology
  • Molecular Biology


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