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Protein folding in the periplasm in the absence of primary oxidant DsbA: modulation of redox potential in periplasmic space via OmpL porin
Author(s) -
Dartigalongue Claire,
Nikaido Hiroshi,
Raina Satish
Publication year - 2000
Publication title -
the embo journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 7.484
H-Index - 392
eISSN - 1460-2075
pISSN - 0261-4189
DOI - 10.1093/emboj/19.22.5980
Subject(s) - periplasmic space , humanities , philosophy , chemistry , gene , biochemistry , escherichia coli
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.