1. Shigella IpaA mediates actin bundling through diffusible vinculin oligomers with activation imprint.
- Author
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Valencia-Gallardo, Cesar, Aguilar-Salvador, Daniel-Isui, Khakzad, Hamed, Cocom-Chan, Benjamin, Bou-Nader, Charles, Velours, Christophe, Zarrouk, Yosra, Le Clainche, Christophe, Malosse, Christian, Lima, Diogo Borges, Quenech'Du, Nicole, Mazhar, Bilal, Essid, Sami, Fontecave, Marc, Asnacios, Atef, Chamot-Rooke, Julia, Malmström, Lars, and Tran Van Nhieu, Guy
- Abstract
Upon activation, vinculin reinforces cytoskeletal anchorage during cell adhesion. Activating ligands classically disrupt intramolecular interactions between the vinculin head and tail domains that bind to actin filaments. Here, we show that Shigella IpaA triggers major allosteric changes in the head domain, leading to vinculin homo-oligomerization. Through the cooperative binding of its three vinculin-binding sites (VBSs), IpaA induces a striking reorientation of the D1 and D2 head subdomains associated with vinculin oligomerization. IpaA thus acts as a catalyst producing vinculin clusters that bundle actin at a distance from the activation site and trigger the formation of highly stable adhesions resisting the action of actin relaxing drugs. Unlike canonical activation, vinculin homo-oligomers induced by IpaA appear to keep a persistent imprint of the activated state in addition to their bundling activity, accounting for stable cell adhesion independent of force transduction and relevant to bacterial invasion. [Display omitted] • Shigella IpaA induces vinculin oligomerization via the D1D2 head subdomains • IpaA-induced vinculin oligomers promote actin bundling • IpaA stimulates the formation of highly stable focal adhesions • Focal adhesions triggered by IpaA form independent of acto-myosin contraction Valencia-Gallardo et al. show that the Shigella invasion effector IpaA induces major conformational changes in the vinculin head domain leading to vinculin oligomerization and actin filament bundling. This non-canonical mode of vinculin activation is required for bacterial invasion and may also be pertinent for the formation of cell adhesion structures. [ABSTRACT FROM AUTHOR]
- Published
- 2023
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