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Molecular basis for LDL receptor recognition by PCSK9.

Proprotein convertase subtilisin/kexin type 9 (PCSK9) posttranslationally regulates hepatic low-density lipoprotein receptors (LDLRs) by binding to LDLRs on the cell surface, leading to their degradation. The binding site of PCSK9 has been localized to the epidermal growth factor-like repeat A (EGF-A) domain of the LDLR. Here, we describe the crystal structure of a complex between PCSK9 and the EGF-A domain of the LDLR. The binding site for the LDLR EGF-A domain resides on the surface of PCSK9's subtilisin-like catalytic domain containing Asp-374, a residue for which a gain-of-function mutation (Asp-374-Tyr) increases the affinity of PCSK9 toward LDLR and increases plasma LDL-cholesterol (LDL-C) levels in humans. The binding surface on PCSK9 is distant from its catalytic site, and the EGF-A domain makes no contact with either the C-terminal domain or the prodomain. Point mutations in PCSK9 that altered key residues contributing to EGF-A binding (Arg-194 and Phe-379) greatly diminished binding to the LDLR's extracellular domain. The structure of PCSK9 in complex with the LDLR EGF-A domain defines potential therapeutic target sites for blocking agents that could interfere with this interaction in vivo, thereby increasing LDLR function and reducing plasma LDL-C levels.

Pubmed ID: 18250299

Authors

  • Kwon HJ
  • Lagace TA
  • McNutt MC
  • Horton JD
  • Deisenhofer J

Journal

Proceedings of the National Academy of Sciences of the United States of America

Publication Data

February 12, 2008

Associated Grants

  • Agency: NIGMS NIH HHS, Id: GM08014
  • Agency: NHLBI NIH HHS, Id: HL-20948
  • Agency: NHLBI NIH HHS, Id: HL-38049

Mesh Terms

  • Binding Sites
  • Cell Line
  • Epidermal Growth Factor
  • Humans
  • Hydrogen-Ion Concentration
  • Lipoproteins, LDL
  • Models, Molecular
  • Mutagenesis, Site-Directed
  • Proprotein Convertases
  • Protein Binding
  • Protein Conformation
  • Receptors, LDL
  • Serine Endopeptidases