6dv1
From Proteopedia
Crystal structure of the alpha-E-catenin actin-binding domain
Structural highlights
Function[CTNA1_MOUSE] Associates with the cytoplasmic domain of a variety of cadherins. The association of catenins to cadherins produces a complex which is linked to the actin filament network, and which seems to be of primary importance for cadherins cell-adhesion properties. Can associate with both E- and N-cadherins. Originally believed to be a stable component of E-cadherin/catenin adhesion complexes and to mediate the linkage of cadherins to the actin cytoskeleton at adherens junctions. In contrast, cortical actin was found to be much more dynamic than E-cadherin/catenin complexes and CTNNA1 was shown not to bind to F-actin when assembled in the complex suggesting a different linkage between actin and adherens junctions components. The homodimeric form may regulate actin filament assembly and inhibit actin branching by competing with the Arp2/3 complex for binding to actin filaments. May play a crucial role in cell differentiation.[1] Publication Abstract from PubMedalpha-catenin is a key mechanosensor that forms force-dependent interactions with F-actin, thereby coupling the cadherin-catenin complex to the actin cytoskeleton at adherens junctions (AJs). However, the molecular mechanisms by which alpha-catenin engages F-actin under tension remained elusive. Here we show that the alpha1-helix of the alpha-catenin actin-binding domain (alphacat-ABD) is a mechanosensing motif that regulates tension-dependent F-actin binding and bundling. alphacat-ABD containing an alpha1-helix-unfolding mutation (H1) shows enhanced binding to F-actin in vitro. Although full-length alpha-catenin-H1 can generate epithelial monolayers that resist mechanical disruption, it fails to support normal AJ regulation in vivo. Structural and simulation analyses suggest that alpha1-helix allosterically controls the actin-binding residue V796 dynamics. Crystal structures of alphacat-ABD-H1 homodimer suggest that alpha-catenin can facilitate actin bundling while it remains bound to E-cadherin. We propose that force-dependent allosteric regulation of alphacat-ABD promotes dynamic interactions with F-actin involved in actin bundling, cadherin clustering, and AJ remodeling during tissue morphogenesis. Force-dependent allostery of the alpha-catenin actin-binding domain controls adherens junction dynamics and functions.,Ishiyama N, Sarpal R, Wood MN, Barrick SK, Nishikawa T, Hayashi H, Kobb AB, Flozak AS, Yemelyanov A, Fernandez-Gonzalez R, Yonemura S, Leckband DE, Gottardi CJ, Tepass U, Ikura M Nat Commun. 2018 Nov 30;9(1):5121. doi: 10.1038/s41467-018-07481-7. PMID:30504777[2] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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