2KP2

Solution structure of the b' domain of thermophilic fungal protein disulfide isomerase

Summary for 2KP2

• Entry DOI: 10.2210/pdb2kp2/pdb
• Related: 2KP1
• Descriptor: Protein disulfide-isomerase (1 entity in total)
• Functional Keywords: thioredoxin fold, isomerase, disulfide bond, endoplasmic reticulum, redox-active center
• Biological source: Humicola insolens
• Cellular location: Endoplasmic reticulum lumen (By similarity): P55059
• Total number of polymer chains: 1
• Total formula weight: 14505.34

Authors

Kato, K.,Yamaguchi, Y.,Serve, O. (deposition date: 2009-10-06, release date: 2009-10-27, Last modification date: 2024-05-29)

Primary citation

Serve, O.,Kamiya, Y.,Maeno, A.,Nakano, M.,Murakami, C.,Sasakawa, H.,Yamaguchi, Y.,Harada, T.,Kurimoto, E.,Yagi-Utsumi, M.,Iguchi, T.,Inaba, K.,Kikuchi, J.,Asami, O.,Kajino, T.,Oka, T.,Nakasako, M.,Kato, K.
Redox-Dependent Domain Rearrangement of Protein Disulfide Isomerase Coupled with Exposure of Its Substrate-Binding Hydrophobic Surface
J.Mol.Biol., 2009

PubMed Abstract: Protein disulfide isomerase (PDI) is a major protein in the endoplasmic reticulum, operating as an essential folding catalyst and molecular chaperone for disulfide-containing proteins by catalyzing the formation, rearrangement, and breakage of their disulfide bridges. This enzyme has a modular structure with four thioredoxin-like domains, a, b, b', and a', along with a C-terminal extension. The homologous a and a' domains contain one cysteine pair in their active site directly involved in thiol-disulfide exchange reactions, while the b' domain putatively provides a primary binding site for unstructured regions of the substrate polypeptides. Here, we report a redox-dependent intramolecular rearrangement of the b' and a' domains of PDI from Humicola insolens, a thermophilic fungus, elucidated by combined use of nuclear magnetic resonance (NMR) and small-angle X-ray scattering (SAXS) methods. Our NMR data showed that the substrates bound to a hydrophobic surface spanning these two domains, which became more exposed to the solvent upon oxidation of the active site of the a' domain. The hydrogen-deuterium exchange and relaxation data indicated that the redox state of the a' domain influences the dynamic properties of the b' domain. Moreover, the SAXS profiles revealed that oxidation of the a' active site causes segregation of the two domains. On the basis of these data, we propose a mechanistic model of PDI action; the a' domain transfers its own disulfide bond into the unfolded protein accommodated on the hydrophobic surface of the substrate-binding region, which consequently changes into a "closed" form releasing the oxidized substrate.

PubMed: 19944705
DOI: 10.1016/j.jmb.2009.11.049

Experimental method

SOLUTION NMR