7zi0
Structure of human Smoothened in complex with cholesterol and SAG
Structural highlights
FunctionC562_ECOLX Electron-transport protein of unknown function.SMO_HUMAN G protein-coupled receptor that probably associates with the patched protein (PTCH) to transduce the hedgehog's proteins signal. Binding of sonic hedgehog (SHH) to its receptor patched is thought to prevent normal inhibition by patched of smoothened (SMO). Required for the accumulation of KIF7 and GLI3 in the cilia.[1] Publication Abstract from PubMedSmoothened (SMO) transduces the Hedgehog (Hh) signal across the plasma membrane in response to accessible cholesterol. Cholesterol binds SMO at two sites: one in the extracellular cysteine-rich domain (CRD) and a second in the transmembrane domain (TMD). How these two sterol-binding sites mediate SMO activation in response to the ligand Sonic Hedgehog (SHH) remains unknown. We find that mutations in the CRD (but not the TMD) reduce the fold increase in SMO activity triggered by SHH. SHH also promotes the photocrosslinking of a sterol analog to the CRD in intact cells. In contrast, sterol binding to the TMD site boosts SMO activity regardless of SHH exposure. Mutational and computational analyses show that these sites are in allosteric communication despite being 45 angstroms apart. Hence, sterols function as both SHH-regulated orthosteric ligands at the CRD and allosteric ligands at the TMD to regulate SMO activity and Hh signaling. Patched 1 regulates Smoothened by controlling sterol binding to its extracellular cysteine-rich domain.,Kinnebrew M, Woolley RE, Ansell TB, Byrne EFX, Frigui S, Luchetti G, Sircar R, Nachtergaele S, Mydock-McGrane L, Krishnan K, Newstead S, Sansom MSP, Covey DF, Siebold C, Rohatgi R Sci Adv. 2022 Jun 3;8(22):eabm5563. doi: 10.1126/sciadv.abm5563. Epub 2022 Jun 3. PMID:35658032[2] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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