?
DsbA family, DsbA subfamily; DsbA is a monomeric thiol disulfide oxidoreductase protein containing a redox active CXXC motif imbedded in a TRX fold. It is involved in the oxidative protein folding pathway in prokaryotes, and is the strongest thiol oxidant known, due to the unusual stability of the thiolate anion form of the first cysteine in the CXXC motif. The highly unstable oxidized form of DsbA directly donates disulfide bonds to reduced proteins secreted into the bacterial periplasm. This rapid and unidirectional process helps to catalyze the folding of newly-synthesized polypeptides. To regain catalytic activity, reduced DsbA is then reoxidized by the membrane protein DsbB, which generates its disulfides from oxidized quinones, which in turn are reoxidized by the electron transport chain.
|