[A second gene involved in the formation of disulfide bonds in proteins localized in Escherichia coli periplasmic space].

A novel mutant of Escherichia coli was isolated whose phenotype is similar to those of dsbA strains. For instance, it is unable to express pH 2.5 acid phosphatase, glucose-1-phosphatase and alkaline phosphatase in the periplasmic space. The mutation lies at min 26.2 of the linkage map, and does not affect expression of DsbA. Addition of oxidized glutathione to the growth medium restores the wild-type phenotype in the mutant while this is not the case in a dsbA strain. The product of this new gene dsbX is thus actually involved in the formation of disulfide bridges in the periplasmic space but can only operate if DsbA is functional.