2W2N: Wt Pcsk9-Deltac Bound To Egf-A H306y Mutant Of Ldlr

PCSK9 regulates low density lipoprotein receptor (LDLR) levels and consequently is a target for the prevention of atherosclerosis and coronary heart disease. Here we studied the interaction, of LDLR EGF(A/AB) repeats with PCSK9. We show that PCSK9 binds the EGF(AB) repeats in a pH-dependent manner. Although the PCSK9 C-terminal domain is not involved in LDLR binding, PCSK9 autocleavage is required. Moreover, we report the x-ray structure of the PCSK9DeltaC-EGF(AB) complex at neutral pH. Compared with the low pH PCSK9-EGF(A) structure, the new structure revealed rearrangement of the EGF(A) His-306 side chain and disruption of the salt bridge with PCSK9 Asp-374, thus suggesting the basis for enhanced interaction at low pH. In addition, the structure of PCSK9DeltaC bound to EGF(AB)(H306Y), a mutant associated with familial hypercholesterolemia (FH), reveals that the Tyr-306 side chain forms a hydrogen bond with PCSK9 Asp-374, thus mimicking His-306 in the low pH conformation. Consistently, Tyr-306 confers increased affinity for PCSK9. Importantly, we found that although the EGF(AB)(H306Y)-PCSK9 interaction is pH-independent, LDLR(H306Y) binds PCSK9 50-fold better at low pH, suggesting that factors other than His-306 contribute to the pH dependence of PCSK9-LDLR binding. Further, we determined the structures of EGF(AB) bound to PCSK9DeltaC containing the FH-associated D374Y and D374H mutations, revealing additional interactions with EGF(A) mediated by Tyr-374/His-374 and providing a rationale for their disease phenotypes. Finally, we report the inhibitory properties of EGF repeats in a cellular assay measuring LDL uptake.
PDB ID: 2W2NDownload
MMDB ID: 68724
PDB Deposition Date: 2008/11/3
Updated in MMDB: 2008/12
Experimental Method:
x-ray diffraction
Resolution: 2.3  Å
Source Organism:
Similar Structures:
Biological Unit for 2W2N: trimeric; determined by author and by software (PQS)
Molecular Components in 2W2N
Label Count Molecule
Proteins (3 molecules)
Proprotein Convertase Subtilisinkexin Type 9(Gene symbol: PCSK9)
Molecule annotation
Proprotein Convertase Subtilisinkexin Type 9(Gene symbol: PCSK9)
Molecule annotation
Low-density Lipoprotein Receptor(Gene symbol: LDLR)
Molecule annotation
Chemicals (3 molecules)
* Click molecule labels to explore molecular sequence information.

Citing MMDB