Quercetin-3-rutinoside Inhibits Protein Disulfide Isomerase by Binding to Its b'x Domain

• Published in: The Journal of biological chemistry 2015-09, Vol.290 (39), p.23543
• Main Authors: Lin, Lin, Gopal, Srila, Sharda, Anish, Passam, Freda, Bowley, Sheryl R, Stopa, Jack, Xue, Guangpu, Yuan, Cai, Furie, Barbara C, Flaumenhaft, Robert, Huang, Mingdong, Furie, Bruce
• Format: Article
• Language: English
• Subjects: Animals; Binding Sites; Calorimetry; Humans; Inhibitory Concentration 50; Mice; Mice, Inbred C57BL; Protein Disulfide-Isomerases - antagonists & inhibitors; Protein Disulfide-Isomerases - metabolism; Rutin - metabolism; Rutin - pharmacology; Scattering, Small Angle; Thrombosis - prevention & control; X-Ray Diffraction
• ISSN: 1083-351X
• DOI: 10.1074/jbc.M115.666180

Quercetin-3-rutinoside inhibits thrombus formation in a mouse model by inhibiting extracellular protein disulfide isomerase (PDI), an enzyme required for platelet thrombus formation and fibrin generation. Prior studies have identified PDI as a potential target for novel antithrombotic agents. Using a fluorescence enhancement-based assay and isothermal calorimetry, we show that quercetin-3-rutinoside directly binds to the b' domain of PDI with a 1:1 stoichiometry. The binding of quercetin-3-rutinoside to PDI induces a more compact conformation and restricts the conformational flexibility of PDI, as revealed by small angle x-ray scattering. The binding sites of quercetin-3-rutinoside to PDI were determined by studying its interaction with isolated fragments of PDI. Quercetin-3-rutinoside binds to the b'x domain of PDI. The infusion of the b'x fragment of PDI rescued thrombus formation that was inhibited by quercetin-3-rutinoside in a mouse thrombosis model. This b'x fragment does not possess reductase activity and, in the absence of quercetin-3-rutinoside, does not affect thrombus formation in vivo. The isolated b' domain of PDI has potential as an antidote to reverse the antithrombotic effect of quercetin-3-rutinoside by binding and neutralizing quercetin-3-rutinoside.