[Redox properties and conformational changes of DsbA protein from Escherichia coli periplasm]

DsbA protein, a disulfide bond enzyme in Escherichia coli periplasm, catalyzes mainly disulfide bond formation of proteins. Site-directed mutagenes is combined with Trp-analog labeling technique was used to investigate the redox properties and conformational changes of DsbA. The results show that: (1) DsbA, as an oxidase, can catalyze disulfide bond formation efficiently. The reduced form is more stable than the oxidized form, suggesting that the strong oxidizing force of DsbA comes from the tense conformation of the oxidized form. (2) The alteration of local environment around Trp(76) between redox forms is responsible for the special fluorescence phenomenon of DsbA. (3) The result from (19)F-NMR study provides further evidence that the local conformation of Trp(76) is dramatically affected during the transformation of redox forms, but that of Trp(126) remains unaffected.