Crystal structure of a multi-domain human smoothened receptor in complex with a super stabilizing ligand.
Zhang, X., Zhao, F., Wu, Y., Yang, J., Han, G.W., Zhao, S., Ishchenko, A., Ye, L., Lin, X., Ding, K., Dharmarajan, V., Griffin, P.R., Gati, C., Nelson, G., Hunter, M.S., Hanson, M.A., Cherezov, V., Stevens, R.C., Tan, W., Tao, H., Xu, F.(2017) Nat Commun 8: 15383-15383
- PubMed: 28513578 
- DOI: https://doi.org/10.1038/ncomms15383
- Primary Citation of Related Structures:  
5V56, 5V57 - PubMed Abstract: 
The Smoothened receptor (SMO) belongs to the Class Frizzled of the G protein-coupled receptor (GPCR) superfamily, constituting a key component of the Hedgehog signalling pathway. Here we report the crystal structure of the multi-domain human SMO, bound and stabilized by a designed tool ligand TC114, using an X-ray free-electron laser source at 2.9 Å. The structure reveals a precise arrangement of three distinct domains: a seven-transmembrane helices domain (TMD), a hinge domain (HD) and an intact extracellular cysteine-rich domain (CRD). This architecture enables allosteric interactions between the domains that are important for ligand recognition and receptor activation. By combining the structural data, molecular dynamics simulation, and hydrogen-deuterium-exchange analysis, we demonstrate that transmembrane helix VI, extracellular loop 3 and the HD play a central role in transmitting the signal employing a unique GPCR activation mechanism, distinct from other multi-domain GPCRs.
Organizational Affiliation: 
iHuman Institute, ShanghaiTech University, 2F Building 6, 99 Haike Road, Pudong New District, Shanghai 201210, China.