title: The OmpL porin does not modulate redox potential in the periplasmic space of Escherichia coli.
abstract: The Escherichia coli DsbA protein is the major oxidative catalyst in the periplasm. Dartigalongue et al. (EMBO J., 19, 5980-5988, 2000) reported that null mutations in the ompL gene of E.coli fully suppress all phenotypes associated with dsbA mutants, i.e. sensitivity to the reducing agent dithiothreitol (DTT) and the antibiotic benzylpenicillin, lack of motility, reduced alkaline phosphatase activity and mucoidy. They showed that OmpL is a porin and hypothesized that ompL null mutations exert their suppressive effect by preventing efflux of a putative oxidizing-reducing compound into the medium. We have repeated these experiments using two different ompL null alleles in at least three different E.coli K-12 genetic backgrounds and have failed to reproduce any of the ompL suppressive effects noted above. Also, we show that, contrary to earlier results, ompL null mutations alone do not result in partial DTT sensitivity or partial motility, nor do they appreciably affect bacterial growth rates or block propagation of the male-specific bacteriophage M13. Thus, our findings clearly demonstrate that ompL plays no perceptible role in modulating redox potential in the periplasm of E.coli.
authors.affiliation: Département de Biochimie Médicale, Centre Médical Universitaire, Université de Genève, 1 rue Michel-Servet, CH-1211 Genève 4, Switzerland.
authors.forename: Abhijit A
authors.initials: AA
authors.lastname: Sardesai
authors.forename: Pierre
authors.initials: P
authors.lastname: Genevaux
authors.forename: Françoise
authors.initials: F
authors.lastname: Schwager
authors.forename: Debbie
authors.initials: D
authors.lastname: Ang
authors.forename: Costa
authors.initials: C
authors.lastname: Georgopoulos
mesh_terms: D000469:Alkaline Phosphatase / Q000378:metabolism; D001426:Bacterial Proteins; D001483:Base Sequence; D017931:DNA Primers; D004229:Dithiothreitol / Q000494:pharmacology; D004926:Escherichia coli / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism*; D029968:Escherichia coli Proteins; D005798:Genes, Bacterial; D009154:Mutation; D010084:Oxidation-Reduction; D019897:Periplasm / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism*; D018272:Porins / Q000235:genetics / Q000502:physiology*; D019704:Protein Disulfide-Isomerases / Q000235:genetics
chemical_list: D001426:Bacterial Proteins; D017931:DNA Primers; D029968:Escherichia coli Proteins; C491058:OmpL protein, E coli; C100900:OmpL protein, bacteria; D018272:Porins; D000469:Alkaline Phosphatase; D019704:Protein Disulfide-Isomerases; D004229:Dithiothreitol