Periplasmic protein thiol : disulfide oxidoreductases of Escherichia coli

Disulfide bond formation is part of the folding pathway for many periplasmi c and outer membrane proteins that contain structural disulfide bonds. In E scherichia coli, a broad variety of periplasmic protein thiol:disulfide oxi doreductases have been identified in recent years, which substantially cont ribute to this pathway. Like the well-known cytoplasmic thioredoxins and gl utaredoxins, these periplasmic protein thiol:disulfide oxidoreductases cont ain the conserved C-X-X-C motif in their active site. Most of them have a d omain that displays the thioredoxin-like fold. In contrast to the cytoplasm ic system, which consists exclusively of reducing proteins, the periplasmic oxidoreductases have either an oxidising, a reducing or an isomerisation a ctivity. Apart from understanding their physiological role, it is of intere st to learn how these proteins interact with their target molecules and how they are recycled as electron donors or accepters. This review reflects th e recently made efforts to elucidate the sources of oxidising and reducing power in the periplasm as well as the different properties of certain perip lasmic protein thiol:disulfide oxidoreductases of E. coli. (C) 2000 Federat ion of European Microbiological Societies. Published by Elsevier Science B. V. All rights reserved.