Redox Properties and Conformational Changes of DsbA protein from Escherichia coli Periplasm

LI Qi, HU Hong-Yu^*
( Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences,
the Chinese Academy of Sciences, Shanghai 200031, China )

Abstract    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 Trp⁷⁶ between redox forms is responsible for the special fluorescence phenomenon of DsbA. (3) The result from ¹⁹F-NMR study provides further evidence that the local conformation of Trp⁷⁶ is dramatically affected during the transformation of redox forms, but that of Trp¹²⁶ remains unaffected.

Key words    DsbA protein; redox property; conformational change; site-directed mutagenesis; Trp-analog labeling

^*Corresponding author: Tel, 86-21-64374430-5121; Fax, 86-21-64338357; e-mail, [email protected]