A conformational-dependent interdomain redox relay at the core of Protein Disulfide Isomerase activity

Abstract

Protein disulfide isomerases (PDIs) are a family of molecular chaperones resident in the endoplasmic reticulum (ER) emerging as important factors in disease. In addition to an holdase function, some members catalyse disulfide bond formation and isomerization, a crucial step for native folding and prevention of aggregation of misfolded proteins. PDIs are characterized by a modular arrangement of thioredoxin-like domains, with the canonical, first identified PDIA1, organized as four thioredoxin-like domains forming a horseshoe with two active sites at the extremities. Using two fluorescent redox sensors, roGFP2 and HyPer, as client substrates either unfolded or native, and the in vitro reconstitution of the full pathways of oxidative protein in the ER, we clarified important aspects underlying the catalytic cycle of PDIA1.