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Science. 2012 Sep 28;337(6102):1665-8. Epub 2012 Aug 30.

Disulfide rearrangement triggered by translocon assembly controls lipopolysaccharide export.

Author information

1
Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA 02138, USA.

Abstract

The presence of lipopolysaccharide (LPS) on the cell surface of Gram-negative bacteria is critical for viability. A conserved β-barrel membrane protein LptD (lipopolysaccharide transport protein D) translocates LPS from the periplasm across the outer membrane (OM). In Escherichia coli, this protein contains two disulfide bonds and forms the OM LPS translocon with the lipoprotein LptE. Here, we identified seven in vivo states on the oxidative-folding pathway of LptD. Proper assembly involved a nonfunctional intermediate containing non-native disulfides. Intermediate formation required the oxidase DsbA, and subsequent maturation to the active form with native disulfides was triggered by LptE. Thus, disulfide bond-dependent protein folding of LptD requires the proper assembly of a two-protein complex to promote disulfide bond rearrangement.

PMID:
22936569
PMCID:
PMC3489181
DOI:
10.1126/science.1227215
[Indexed for MEDLINE]
Free PMC Article

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