6u38 | pdb_00006u38
PCSK9 in complex with a Fab and compound 8
Structural highlights
Disease[PCSK9_HUMAN] Defects in PCSK9 are the cause of hypercholesterolemia autosomal dominant type 3 (HCHOLA3) [MIM:603776]. A familial condition characterized by elevated circulating cholesterol contained in either low-density lipoproteins alone or also in very-low-density lipoproteins.[1] Function[PCSK9_HUMAN] Crucial player in the regulation of plasma cholesterol homeostasis. Binds to low-density lipid receptor family members: low density lipoprotein receptor (LDLR), very low density lipoprotein receptor (VLDLR), apolipoprotein E receptor (LRP1/APOER) and apolipoprotein receptor 2 (LRP8/APOER2), and promotes their degradation in intracellular acidic compartments. Acts via a non-proteolytic mechanism to enhance the degradation of the hepatic LDLR through a clathrin LDLRAP1/ARH-mediated pathway. May prevent the recycling of LDLR from endosomes to the cell surface or direct it to lysosomes for degradation. Can induce ubiquitination of LDLR leading to its subsequent degradation. Inhibits intracellular degradation of APOB via the autophagosome/lysosome pathway in a LDLR-independent manner. Involved in the disposal of non-acetylated intermediates of BACE1 in the early secretory pathway. Inhibits epithelial Na(+) channel (ENaC)-mediated Na(+) absorption by reducing ENaC surface expression primarily by increasing its proteasomal degradation. Regulates neuronal apoptosis via modulation of LRP8/APOER2 levels and related anti-apoptotic signaling pathways.[2] [3] [4] [5] [6] [7] [8] Publication Abstract from PubMedProprotein convertase substilisin-like/kexin type 9 (PCSK9) is a serine protease involved in a protein-protein interaction with the low-density lipoprotein (LDL) receptor that has both human genetic and clinical validation. Blocking this protein-protein interaction prevents LDL receptor degradation and thereby decreases LDL cholesterol levels. Our pursuit of small-molecule direct binders for this difficult to drug PPI target utilized affinity selection/mass spectrometry, which identified one confirmed hit compound. An X-ray crystal structure revealed that this compound was binding in an unprecedented allosteric pocket located between the catalytic and C-terminal domain. Optimization of this initial hit, using two distinct strategies, led to compounds with high binding affinity to PCSK9. Direct target engagement was demonstrated in the cell lysate with a cellular thermal shift assay. Finally, ligand-induced protein degradation was shown with a proteasome recruiting tag attached to the high-affinity allosteric ligand for PCSK9. From Screening to Targeted Degradation: Strategies for the Discovery and Optimization of Small Molecule Ligands for PCSK9.,Petrilli WL, Adam GC, Erdmann RS, Abeywickrema P, Agnani V, Ai X, Baysarowich J, Byrne N, Caldwell JP, Chang W, DiNunzio E, Feng Z, Ford R, Ha S, Huang Y, Hubbard B, Johnston JM, Kavana M, Lisnock JM, Liang R, Lu J, Lu Z, Meng J, Orth P, Palyha O, Parthasarathy G, Salowe SP, Sharma S, Shipman J, Soisson SM, Strack AM, Youm H, Zhao K, Zink DL, Zokian H, Addona GH, Akinsanya K, Tata JR, Xiong Y, Imbriglio JE Cell Chem Biol. 2019 Oct 22. pii: S2451-9456(19)30322-8. doi:, 10.1016/j.chembiol.2019.10.002. PMID:31653597[9] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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