A Chemical Ground of de novo Protein Disulfide Bond Generation in the Cell

Many secretory proteins undergo oxidative folding, during which they acquire intra- or intermolecular disulfide bonds. In the periplasm of Escherichia coli, DsbA functions as a primary disulfide bond donor. DsbB, which is responsible for reoxidation of DsbA, acts as a molecular machine that transforms an oxidizing equivalent of ubiquinone into a protein disulfide. A similar oxidative system exists in the ER of eukaryotic cells, where Ero1p and FAD play a pivotal role in the disulfide bond creation. This review describes the reaction mechanism of ubiquinone-dependent dithiol oxidation in Escherichia coli and proposes its similarities to the eukaryotic FAD-dependent one.