Intriguing Conformation Changes Associated with the Trans/Cis Isomerization of a Prolyl Residue in the Active Site of the DsbA C33A Mutant Original Research Article

Escherichia coli DsbA belongs to the thioredoxin family and catalyzes the formation of disulfide bonds during the folding of proteins in the bacterial periplasm. It active site (C30–P31–H32–C33) consists of a disulfide bridge that is transferred to newly translocated proteins. The work reported here refers to the DsbA mutant termed C33A that retains, towards reduced unfolded thrombin inhibitor, an activity comparable with the wild-type enzyme. Besides, C33A is also able to form a stable covalent complex with DsbB, the membrane protein responsible for maintaining DsbA in its active form.