The b′ domain of protein disulfide isomerase cooperates with the a and a′ domains to functionally interact with platelets
Author(s): ,
Lu Wang
Affiliations:
Sol Sherry Thrombosis Research Center, Division of Hematology, Department of Medicine, Temple University School of Medicine, Philadelphia, USA. National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
,
Junsong Zhou
Affiliations:
Sol Sherry Thrombosis Research Center, Division of Hematology, Department of Medicine, Temple University School of Medicine, Philadelphia, USA. The Cyrus Tang Hematology Center, Jiangsu Institute of Hematology, Collaborative Innovation Center of Hematology, Soochow University, Suzhou, China
,
Lei Wang
Affiliations:
National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China. College of Life Sciences, University of Chinese Academy of Sciences, Beijing, China
,
Chih‐chen Wang
Affiliations:
National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China. College of Life Sciences, University of Chinese Academy of Sciences, Beijing, China
David W. Essex
Affiliations:
Sol Sherry Thrombosis Research Center, Division of Hematology, Department of Medicine, Temple University School of Medicine, Philadelphia, USA
Correspondence: David W. Essex, Temple University School of Medicine, Room 204 MRB, 3420 North Broad Street, Philadelphia, PA 19140, USA|Tel.: +1 215 707 6356|E‐mail: essex@temple.edu
ISTH Academy. Essex D. Feb 8, 2019; 273366
David Essex
David Essex
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Background
Protein disulfide isomerase (PDI) is an oxidoreductase consisting of four domains arranged in the order a–b–b′–a′ with an x‐linker between the b′ and a′ domains. PDI binds to αβ integrin on activated platelets, and potentiates activation of this integrin through the C‐terminal CGHC active‐site motif. How PDI binds to platelet αβ is unknown.
Objective and methods
We used PDI domain fragments and full‐length PDI containing point mutations to study inhibition of Alexa 488‐labeled PDI binding to thrombin‐activated platelets. The effect of the PDI variants on platelet aggregation was tested.
Results
Only PDI fragments containing the b′ domain bound to activated platelets. A double mutant of the b′ domain had decreased binding, confirming the essential role of the b′ domain. Addition of mutations in the a and a′ domains further decreased binding, suggesting that these domains contribute to the interaction of PDI with platelets. The ability of the b′ domain to interact directly with αβ was demonstrated with surface plasmon resonance, with contributions from the a and a′ domains. The abb′x PDI fragment that binds to platelets but lacks the critical C‐terminal active site inhibited platelet aggregation and in vivo thrombosis. Moreover, site mutations in the a, b′ and a′ domains that resulted in partial binding to platelets partially recovered aggregation of PDI‐null platelets. PDI mutants that did not bind showed no recovery.
Conclusion
PDI functionally interacts with αβ on platelets through the substrate‐binding b′ domain, with the a and a′ domains contributing to efficient binding.
Keyword(s)
disulfide, integrin, platelet, protein disulfide isomerase, sulfhydryl, thrombosis
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