Characterization of DsbC, a periplasmic protein of Erwinia chrysanthemi and Escherichia coli with disulfide isomerase activity.
We identified and characterized an Erwinia chrysanthemi gene able to complement an Escherichia coli dsbA mutation that prevents disulfide bond formation in periplasmic proteins. This gene, dsbC, codes for a 24 kDa periplasmic protein that contains a characteristic active site sequence of disulfide isomerases, Phe-X-X-X-X-Cys-X-X-Cys. Besides the active site, DsbC has no homology with DsbA, thioredoxin or eukaryotic protein disulfide isomerase and it could define a new subfamily of disulfide isomerases. Purified DsbC protein is able to catalyse insulin oxidation in a dithiothreitol dependent manner. The E.coli gene xprA codes for a protein functionally equivalent to DsbC. The in vivo function of DsbC seems to be the formation of disulfide bonds in proteins. The presence of XprA could explain the residual disulfide isomerase activity existing in dsbA mutants. Re-oxidation of XprA does not seem to occur through DsbB, the protein that probably re-oxidizes DsbA.
Shevchik
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VE
Laboratoire de Génétique Moléculaire des Microorganismes, CNRS URA 1486, Villeubanne, France.
Condemine
G
G
Robert-Baudouy
J
J
D000595:Amino Acid Sequence; D001483:Base Sequence; D002451:Cell Compartmentation; D003001:Cloning, Molecular; D016974:Dickeya chrysanthemi / Q000201:enzymology / Q000235:genetics*; D004926:Escherichia coli / Q000201:enzymology / Q000235:genetics*; D005798:Genes, Bacterial / Q000235:genetics; D005816:Genetic Complementation Test; D007535:Isomerases / Q000235:genetics*; D008565:Membrane Proteins / Q000235:genetics*; D008969:Molecular Sequence Data; D009154:Mutation; D019704:Protein Disulfide-Isomerases; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid
D008565:Membrane Proteins; D007535:Isomerases; D019704:Protein Disulfide-Isomerases