dsbB

dsbB encodes DsbB, a membrane-anchored oxidoreductase that participates in disulfide bond formation in the periplasm of many Gram-negative bacteria. It works in the bacterial Dsb (disulfide bond) system to ensure proper folding of extracytoplasmic proteins, many of which require disulfide bonds for stability and activity. DsbA is the primary oxidase that introduces disulfide bonds into substrate proteins, becoming reduced in the process; DsbB reoxidizes DsbA, transferring electrons from DsbA to the membrane quinone pool and thereby sustaining continuous disulfide bond formation.

Mechanism-wise, DsbB is an inner membrane protein with multiple transmembrane helices. It contains conserved cysteine residues in periplasmic loops that cycle between reduced and oxidized states, acting as an electron relay between DsbA and the quinone pool. Through this redox cycling, DsbA remains available to catalyze the formation of disulfide bonds in folding proteins across the periplasm.

Genetically, dsbB is part of the broader dsb oxidative pathway and is commonly found in conjunction with dsbA in many bacterial species. The DsbA–DsbB system is essential for the correct folding of a wide range of periplasmic and secreted proteins; in some pathogens, this includes virulence factors and surface structures, linking DsbB function to pathogenicity.

Distribution and significance, in short,: the dsbA–dsbB pair is widely conserved among Gram-negative bacteria and is central to envelope protein folding. Disrupting DsbB activity can impair disulfide bond formation, affecting protein maturation, virulence factor function, and the assembly of surface components in certain organisms.