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Crystal Structure Of the Reduced Protein Disulfide Bond Isomerase DsbG
Structural highlights
FunctionDSBG_ECOLI Involved in disulfide bond formation. DsbG and DsbC are part of a periplasmic reducing system that controls the level of cysteine sulfenylation, and provides reducing equivalents to rescue oxidatively damaged secreted proteins such as ErfK, YbiS and YnhG. Probably also functions as a disulfide isomerase with a narrower substrate specificity than DsbC. DsbG is maintained in a reduced state by DsbD. Displays chaperone activity in both redox states in vitro.[1] Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedDsb proteins control the formation and rearrangement of disulfide bonds during the folding of secreted and membrane proteins in bacteria. DsbG, a member of this family, has disulfide bond isomerase and chaperone activity. Here, we present two crystal structures of DsbG at 1.7and 2.0-A resolution that are meant to represent the reduced and oxidized forms, respectively. The oxidized structure, however, reveals a mixture of both redox forms, suggesting that oxidized DsbG is less stable than the reduced form. This trait would contribute to DsbG isomerase activity, which requires that the active-site Cys residues are kept reduced, regardless of the highly oxidative environment of the periplasm. We propose that a Thr residue that is conserved in the cis-Pro loop of DsbG and DsbC but not found in other Dsb proteins could play a role in this process. Also, the structure of DsbG reveals an unanticipated and surprising feature that may help define its specific role in oxidative protein folding. Thus, the dimensions and surface features of DsbG show a very large and charged binding surface that is consistent with interaction with globular protein substrates having charged surfaces. This finding suggests that, rather than catalyzing disulfide rearrangement in unfolded substrates, DsbG may preferentially act later in the folding process to catalyze disulfide rearrangement in folded or partially folded proteins. Crystal structures of the DsbG disulfide isomerase reveal an unstable disulfide.,Heras B, Edeling MA, Schirra HJ, Raina S, Martin JL Proc Natl Acad Sci U S A. 2004 Jun 15;101(24):8876-81. Epub 2004 Jun 7. PMID:15184683[2] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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