High-resolution mapping of the actin fusion focus reveals myosin V–dependent formin transport for aster formation

Article Article scientifique Article High-resolution mapping of the actin fusion focus reveals myosin V–dependent formin transport for aster formation eng 2025-12-03 2026-02-02 author Thomas Valentine 0009-0005-6381-1892 Department of Molecular and Cellular Biology, University of Geneva, Geneva, Switzerland. 403508 author Mase Hikari 0009-0001-8912-7870 Department of Molecular and Cellular Biology, University of Geneva, Geneva, Switzerland. 413973 Département de biologie moléculaire et cellulaire (MOCEL) author Michon Laetitia 0009-0006-7671-6680 Department of Molecular and Cellular Biology, University of Geneva, Geneva, Switzerland. 135169 Département de biologie moléculaire et cellulaire (MOCEL) author Picco Andrea 0000-0003-2548-9183 Department of Biochemistry, University of Geneva, Geneva, Switzerland. 842776 author Kaksonen Marko 0000-0003-3645-7689 Department of Biochemistry, University of Geneva, Geneva, Switzerland. 830048 Département de biochimie (CHIBI) author Martin Sophie 0000-0002-5317-2557 Department of Molecular and Cellular Biology, University of Geneva, Geneva, Switzerland.,Department of Fundamental Microbiology, University of Lausanne, Lausanne, Switzerland. 403314 Département de biologie moléculaire et cellulaire (MOCEL) e202510018 10.1083/jcb.202510018 41335110 0021-9525 https://rupress.org/jcb/article/225/2/e202510018/278548/High-resolution-mapping-of-the-actin-fusion-focus Many processes such as polarized growth and secretion require specific actin networks. In fungi, cell-cell fusion requires cell wall digestion mediated by local secretion of lytic enzymes. In Schizosaccharomyces pombe, the myosin V Myo52 transports enzyme-containing secretory vesicles on the actin fusion focus, an aster-like actin network assembled by the condensate-forming formin Fus1. The fusion focus also concentrates proteins regulating cell polarity, communication, cytoskeleton, exocytosis, and membrane merging. Here, using centroid tracking and averaging, we present a spatiotemporal map of the fusion site with 8-nm precision. We show that a pool of vesicles remains at constant distance from the membrane as the actin structure condenses. Unexpectedly, Myo52 detaches from this pool and colocalizes with Fus1 closer to the membrane. We show that Myo52 binds Fus1 and transports it along actin filaments, and that Myo52 and Fus1 actin assembly activity contribute to focus compaction. Thus, myosin V-driven transport of formin Fus1 along Fus1-nucleated actin filaments underlies positive feedback for actin aster formation. Dewey 540 Dewey 570 Swiss National Science Foundation Mechanisms of cell polarization initiation 176396 CH European Commission Mechanisms of gradient decoding in fission yeast 101019630 SexYeast EU H2020 7daed2ee-1311-4824-9df9-2e51260a966a Département de biologie moléculaire et cellulaire 16484 39 Département de biochimie 144 false 1410 Groupe Sophie Martin 1397 Groupe Kaksonen The Journal of cell biology 225 2 4b64d639-c65f-4937-a156-d3360388c63d Article (Accepted version) Public Thomas_accepted_ms.pdf 17344327 application/pdf CC BY-4.0 20e4910f26dcabdf94d67e77d1fb9b8ace753d071fa0b009beb49de691e36542 de5df8cf-7743-4f20-8b97-bf0f8f1c97fe Article (Published version) Restricted jcb_202510018.pdf 9667916 application/pdf 3cc3353503bed9cf0da5c160431333711921213c4f463950d6aedd628de92102 openAccess Faculté des sciences / Section de biologie / Département de biologie moléculaire et cellulaire Faculté des sciences / Section de chimie et biochimie / Département de biochimie

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High-resolution mapping of the actin fusion focus reveals myosin V–dependent formin transport for aster formation	The Journal of cell biology			2026	17	18

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