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Structures of factor XI and prekallikrein bound to domain 6 of high–molecular weight kininogen reveal alternate domain 6 conformations and exosites

2023; Elsevier BV; Volume: 21; Issue: 9 Linguagem: Inglês

10.1016/j.jtha.2023.03.042

1538-7933

Chan Li, Awital Bar Barroeta, Szu Shen Wong, Hyo Jung Kim, Monika Pathak, Ingrid Dreveny, Joost C.M. Meijers, Jonas Emsley,

Mast cells and histamine

Background: High-molecular weight kininogen (HK) circulates in plasma as a complex with zymogen prekallikrein (PK).HK is both a substrate and a cofactor for activated plasma kallikrein, and the principal exosite interactions occur between PK N-terminal apple domains and the C-terminal D6 domain of HK.Objectives: To determine the structure of the complex formed between PK apple domains and an HKD6 fragment and compare this with the coagulation factor XI (FXI)-HK complex.Methods: We produced recombinant FXI and PK heavy chains (HCs) spanning all 4 apple domains.We cocrystallized PKHC (and subsequently FXIHC) with a 31-amino acid synthetic peptide spanning HK residues Ser565-Lys595 and determined the crystal structure.We also analyzed the full-length FXI-HK complex in solution using hydrogen deuterium exchange mass spectrometry.Results: The 2.3Å PKHC-HK peptide crystal structure revealed that the HKD6 sequence WIPDIQ (Trp569-Gln574) binds to the apple 1 domain and HK FNPISDFPDT (Phe582-Thr591) binds to the apple 2 domain with a flexible intervening sequence resulting in a bent double conformation.A second 3.2Å FXIHC-HK peptide crystal structure revealed a similar interaction with the apple 2 domain but an alternate, straightened conformation of the HK peptide where residues LSFN (Leu579-Asn583) interacts with a unique pocket formed between the apple 2 and 3 domains.HDX-MS of full length FXI-HK complex in solution confirmed interactions with both apple 2 and apple 3. Conclusions:The alternate conformations and exosite binding of the HKD6 peptide likely reflects the diverging relationship of HK to the functions of PK and FXI.