Characterization of DsbC, a periplasmic protein of Erwinia chrysanthemi and Escherichia coli with disulfide isomerase activity.

Vladimir E Shevchik (1, 2) , G. Condemine (3, 1, 2) , J Robert-Baudouy

1 MAP - Microbiologie, adaptation et pathogénie
2 MTSB - Trafic et signalisation membranaires chez les bactéries
3 UMG - Unité de Microbiologie et génétique

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.

Domaines: Chimie; Sciences du Vivant [q-bio]

Vladimir E Shevchik, G. Condemine, J Robert-Baudouy. Characterization of DsbC, a periplasmic protein of Erwinia chrysanthemi and Escherichia coli with disulfide isomerase activity.. EMBO Journal, 1994, 13 (8), pp.2007-12. ⟨hal-03102873⟩