title: A substrate-driven allosteric switch that enhances PDI catalytic activity.
abstract: Protein disulfide isomerase (PDI) is an oxidoreductase essential for folding proteins in the endoplasmic reticulum. The domain structure of PDI is a-b-b'-x-a', wherein the thioredoxin-like a and a' domains mediate disulfide bond shuffling and b and b' domains are substrate binding. The b' and a' domains are connected via the x-linker, a 19-amino-acid flexible peptide. Here we identify a class of compounds, termed bepristats, that target the substrate-binding pocket of b'. Bepristats reversibly block substrate binding and inhibit platelet aggregation and thrombus formation in vivo. Ligation of the substrate-binding pocket by bepristats paradoxically enhances catalytic activity of a and a' by displacing the x-linker, which acts as an allosteric switch to augment reductase activity in the catalytic domains. This substrate-driven allosteric switch is also activated by peptides and proteins and is present in other thiol isomerases. Our results demonstrate a mechanism whereby binding of a substrate to thiol isomerases enhances catalytic activity of remote domains.
authors: Division of Hemostasis and Thrombosis, Department of Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts 02115, USA.
authors: Roelof H
authors: RH
authors: Bekendam
authors: Division of Hemostasis and Thrombosis, Department of Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts 02115, USA.
authors: Pavan K
authors: PK
authors: Bendapudi
authors: Division of Hemostasis and Thrombosis, Department of Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts 02115, USA.
authors: Lin
authors: L
authors: Lin
authors: Department of Pharmaceutical and Administrative Sciences, The Broad Institute Probe Development Center, Cambridge, Massachusetts 02142, USA.|Center for the Science of Therapeutics, Broad Institute, Cambridge, Massachusetts 02142, USA.
authors: Partha P
authors: PP
authors: Nag
authors: Department of Pharmaceutical and Administrative Sciences, The Broad Institute Probe Development Center, Cambridge, Massachusetts 02142, USA.
authors: Jun
authors: J
authors: Pu
authors: College of Pharmacy, Western New England University, Springfield, Massachusetts 01119, USA.
authors: Daniel R
authors: DR
authors: Kennedy
authors: College of Pharmacy, Western New England University, Springfield, Massachusetts 01119, USA.
authors: Alexandra
authors: A
authors: Feldenzer
authors: The Centenary Institute, Newtown, Sydney, New South Wales 2050, Australia.|National Health and Medical Research Council Clinical Trials Centre, University of Sydney, Sydney, New South Wales 2050, Australia.
authors: Joyce
authors: J
authors: Chiu
authors: The Centenary Institute, Newtown, Sydney, New South Wales 2050, Australia.
authors: Kristina M
authors: KM
authors: Cook
authors: Division of Hemostasis and Thrombosis, Department of Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts 02115, USA.
authors: Bruce
authors: B
authors: Furie
authors: Division of Hemostasis and Thrombosis, Department of Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts 02115, USA.
authors: Mingdong
authors: M
authors: Huang
authors: The Centenary Institute, Newtown, Sydney, New South Wales 2050, Australia.|National Health and Medical Research Council Clinical Trials Centre, University of Sydney, Sydney, New South Wales 2050, Australia.
authors: Philip J
authors: PJ
authors: Hogg
authors: Division of Hemostasis and Thrombosis, Department of Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts 02115, USA.
authors: Robert
authors: R
authors: Flaumenhaft
mesh_terms: D000494:Allosteric Regulation / Q000187:drug effects; D000818:Animals; D001792:Blood Platelets / Q000187:drug effects / Q000502:physiology; D020134:Catalytic Domain / Q000187:drug effects; D004195:Disease Models, Animal; D004353:Drug Evaluation, Preclinical; D004721:Endoplasmic Reticulum / Q000378:metabolism*; D004791:Enzyme Inhibitors / Q000494:pharmacology* / Q000627:therapeutic use; D064368:Healthy Volunteers; D006801:Humans; D057927:Hydrophobic and Hydrophilic Interactions / Q000187:drug effects; D007328:Insulin / Q000378:metabolism; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D010974:Platelet Aggregation / Q000187:drug effects*; D011485:Protein Binding / Q000187:drug effects; D019704:Protein Disulfide-Isomerases / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000378:metabolism*; D017510:Protein Folding; D017434:Protein Structure, Tertiary / Q000187:drug effects; D011994:Recombinant Proteins / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism; D013927:Thrombosis / Q000097:blood / Q000188:drug therapy / Q000473:pathology
chemical_list: D004791:Enzyme Inhibitors; D007328:Insulin; D011994:Recombinant Proteins; D019704:Protein Disulfide-Isomerases