PMID:11080145

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Citation

Dartigalongue, C, Nikaido, H and Raina, S (2000) Protein folding in the periplasm in the absence of primary oxidant DsbA: modulation of redox potential in periplasmic space via OmpL porin. EMBO J. 19:5980-8

Abstract

Disulfide bond formation in Escherichia coli is a catalyzed reaction accomplished by DsbA. We found that null mutations in a new porin gene, ompL, allowed a total bypass of the DsbA requirement for protein oxidation. These mutations acted as extragenic null suppressors for dsbA, and restored normal folding of alkaline phosphatase and relieved sensitivity to dithiothreitol. ompL dsbA double mutants were completely like wild-type mutants in terms of motility and lack of mucoidy. This suppression was not dependent on DsbC and DsbG, since the oxidation status of these proteins was unaltered in ompL dsbA strains. Purified OmpL allowed diffusion of small solutes, including sugars, but the suppression was not dependent on the carbon sources used. Suppression by ompL null mutations required DsbB, leading us to propose a hypothesis that DsbB oxidizes yet unidentified, low-molecular-weight redox agents in the periplasm. These oxidized agents accumulate and substitute for DsbA if their leakage into the medium is prevented by the absence of OmpL, presumed to form a specific channel for their diffusion.

Links

PubMed PMC305838 Online version:10.1093/emboj/19.22.5980

Keywords

Amino Acid Sequence; Bacterial Proteins; Base Sequence; Cloning, Molecular; DNA Primers/genetics; Escherichia coli/genetics; Escherichia coli/metabolism; Escherichia coli Proteins; Genes, Bacterial; Molecular Sequence Data; Mutation; Oxidants/metabolism; Oxidation-Reduction; Oxidoreductases/genetics; Oxidoreductases/metabolism; Periplasm/metabolism; Periplasmic Proteins; Phenotype; Porins/chemistry; Porins/genetics; Porins/metabolism; Protein Disulfide-Isomerases/genetics; Protein Disulfide-Isomerases/metabolism; Protein Folding; Sigma Factor/genetics; Suppression, Genetic; Transcription Factors/genetics; Transcription, Genetic

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