Disulfide bond formation protein B (DsbB) is a protein component of the pathway that leads to disulfide bond formation in periplasmic proteins of Escherichia coli and other bacteria. In Bacillus subtilis it is known as BdbC .
The DsbB protein oxidizes the periplasmic protein DsbA which in turn oxidizes cysteines in other periplasmic proteins in order to make disulfide bonds.[1] DsbB acts as a redox potential transducer across the cytoplasmic membrane. It is a membrane protein which spans the membrane four times with both the N- and C-termini of the protein are in the cytoplasm. Each of the periplasmic domains of the protein has two essential cysteines. The two cysteines in the first periplasmic domain are in a Cys-X-Y-Cys configuration that is characteristic of the active site of other proteins involved in disulfide bond formation, including DsbA and protein disulfide isomerase.[2]