Protein disulfide-isomerase interacts with a substrate protein at all stages along its folding pathway.

ABSTRACT: In contrast to molecular chaperones that couple protein folding to ATP hydrolysis, protein disulfide-isomerase (PDI) catalyzes protein folding coupled to formation of disulfide bonds (oxidative folding). However, we do not know how PDI distinguishes folded, partly-folded and unfolded protein substrates. As a model intermediate in an oxidative folding pathway, we prepared a two-disulfide mutant of basic pancreatic trypsin inhibitor (BPTI) and showed by NMR that it is partly-folded and highly dynamic. NMR studies show that it binds to PDI at the same site that binds peptide ligands, with rapid binding and dissociation kinetics; surface plasmon resonance shows its interaction with PDI has a Kd of ca. 10(-5) M. For comparison, we characterized the interactions of PDI with native BPTI and fully

SUBMITTER: Irvine AG 

PROVIDER: S-EPMC3896340 | biostudies-literature | 2014

REPOSITORIES: biostudies-literature