PDBsum entry 6d32

Membrane protein

PDB id: 6d32

Contents

Protein chain

573 a.a.

Ligands

CY8 ×2

PDB id:

6d32

Name:

Membrane protein

Title:

Crystal structure of xenopus smoothened in complex with cyclopamine

Structure:

Smoothened,soluble cytochrome b562,smoothened. Chain: a. Synonym: cytochrome b-562. Engineered: yes

Source:

Xenopus laevis, escherichia coli. African clawed frog. Organism_taxid: 8355, 562. Gene: smo, smo, cybc. Expressed in: spodoptera frugiperda. Expression_system_taxid: 7108

Resolution:

3.75Å R-factor: 0.229 R-free: 0.260

Authors:

P.Huang,S.Zheng,Y.Kim,A.C.Kruse,A.Salic

Key ref:

P.Huang et al. (2018). Structural Basis of Smoothened Activation in Hedgehog Signaling. Cell, 174, 312. PubMed id: 29804838

Date:

14-Apr-18 Release date: 23-May-18

Protein chain

P0ABE7  (C562_ECOLX) -  Soluble cytochrome b562 from Escherichia coli

Seq: 128 a.a.

Struc: 573 a.a.*

* PDB and UniProt seqs differ at 23 residue positions (black crosses)

Cell 174:312 (2018)

PubMed id: 29804838

Structural Basis of Smoothened Activation in Hedgehog Signaling.

P.Huang, S.Zheng, B.M.Wierbowski, Y.Kim, D.Nedelcu, L.Aravena, J.Liu, A.C.Kruse, A.Salic.

ABSTRACT

The seven-transmembrane-spanning protein Smoothened is the central transducer in Hedgehog signaling, a pathway fundamental in development and in cancer. Smoothened is activated by cholesterol binding to its extracellular cysteine-rich domain (CRD). How this interaction leads to changes in the transmembrane domain and Smoothened activation is unknown. Here, we report crystal structures of sterol-activated Smoothened. The CRD undergoes a dramatic reorientation, allosterically causing the transmembrane domain to adopt a conformation similar to active G-protein-coupled receptors. We show that Smoothened contains a unique inhibitory π-cation lock, which is broken on activation and is disrupted in constitutively active oncogenic mutants. Smoothened activation opens a hydrophobic tunnel, suggesting a pathway for cholesterol movement from the inner membrane leaflet to the CRD. All Smoothened antagonists bind the transmembrane domain and block tunnel opening, but cyclopamine also binds the CRD, inducing the active transmembrane conformation. Together, these results define the mechanisms of Smoothened activation and inhibition.