PMID: 30061598

Authors:

Cormier A, Campbell MG, Ito S, Wu S, Lou J, Marks J, Baron JL, Nishimura SL, Cheng Y

Title:

Cryo-EM structure of the alphavbeta8 integrin reveals a mechanism for stabilizing integrin extension.

Journal:

Nat Struct Mol Biol. 2018 Aug;25(8):698-704. doi: 10.1038/s41594-018-0093-x. Epub, 2018 Jul 30.

Abstract:

Integrins are conformationally flexible cell surface receptors that survey the extracellular environment for their cognate ligands. Interactions with ligands are thought to be linked to global structural rearrangements involving transitions between bent, extended-closed and extended-open forms. Thus far, structural details are lacking for integrins in the extended conformations due to extensive flexibility between the headpiece and legs in this conformation. Here we present single-particle electron cryomicroscopy structures of human alphavbeta8 integrin in the extended-closed conformation, which has been considered to be a low-affinity intermediate. Our structures show the headpiece rotating about a flexible alphav knee, suggesting a ligand surveillance mechanism for integrins in their extended-closed form. Our model predicts that the extended conformation is mainly stabilized by an interface formed between flexible loops in the upper and lower domains of the alphav leg. Confirming these findings with the alphavbeta3 integrin suggests that our model of stabilizing the extended-closed conformation is generalizable to other integrins.