Force-dependent allostery of the α-catenin actinbinding domain controls adherens junction dynamics and functions

α-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 α-catenin engages F-actin under tension remained elusive. Here we show that the α1-helix of the α-catenin actin-binding domain (αcat-ABD) is a mechanosensing motif that regulates tension-dependent F-actin binding and bundling. αcat-ABD containing an α1-helix-unfolding mutation (H1) shows enhanced binding to F-actin in vitro. Although full-length α-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 α1-helix allosterically controls the actin-binding residue V796 dynamics. Crystal structures of αcat-ABD-H1 homodimer suggest that α-catenin can facilitate actin bundling while it remains bound to E-cadherin. We propose that force-dependent allosteric regulation of αcat-ABD promotes dynamic interactions with F-actin involved in actin bundling, cadherin clustering, and AJ remodeling during tissue morphogenesis

Drosophila KAP interacts with the kinesin II motor subunit KLP64D to assemble chordotonal sensory cilia, but not sperm tails

and Daniel F. Eberl2,3 1Department of Biological Sciences containing 9�0 axonemal organization of microtubules. Each chordotonal organ neuron has a single long cilium, the assembly of which begins from the distal basal bodies in the dendrite and which is attached to a tubeshaped dendritic cap at the apex. Such chordotonal organs are found in the second antennal segment, where Tata Institute of Fundamental Research they are required for hearing and are called Johnston’s Mumbai 400005 organ (JO), and in various other parts of the body, where India they are required for proprioception. Mutants with audi-2Department of Biological Sciences tory defects were previously found to have defective 3Graduate Program in Neuroscience dendritic cilia in JO neurons [1–3]. The mechanisms tha

Stabilization of the Actomyosin Ring Enables Spermatocyte Cytokinesis in Drosophila

The scaffolding protein anillin recruits septins to the cleavage furrow and constrains actomyosin contractility. Expression of E-cadherin suppresses the cytokinesis defects caused by anillin knockdown and stabilizes F-actin in the furrow, thereby providing an alternate means of coupling the actomyosin ring to the plasma membrane during cytokinesis