Myosin-X sorts actin filaments into parallel bundles and tunes barbed-end dynamics

Kools, W.; Faour, S.; Carlier, A.; Hristova, T.; Sirkia, M. E.; Chaix, L.; Lee, A.; Martin, P.; Houdusse, A.; Romet-Lemonne, G.; JEGOU, A.

doi:10.64898/2026.09.08.749704

bioRxiv · 10.64898/2026.09.08.749704

Myosin-X sorts actin filaments into parallel bundles and tunes barbed-end dynamics

Kools, W.·Faour, S.·Carlier, A.·Hristova, T.·Sirkia, M. E.·Chaix, L.·Lee, A.·Martin, P.·Houdusse, A.·Romet-Lemonne, G.·JEGOU, A.

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Abstract

Whether a molecular motor can spontaneously organize actin filaments into bundles has remained an open question despite decades of in vitro investigation. Here, we show that the dimeric myosin-X, essential for filopodia initiation and extension in cells, is capable of sorting actin filaments into parallel bundles, gathering barbed ends within 1-2 micrometers. We observe that myosin-X processivity is comparable on single filaments and on bundles induced by myosin-X or fascin. Upon reaching barbed ends, myosin-X slows down the addition or removal of actin subunits, in a myosin density-dependent manner. Furthermore, the funneling of myosin-X towards the remaining filaments at the bundle tip increases motor density and triggers dynamic clustering. Together, we propose that the motor activity of myosin-X is sufficient to initiate filopodia, independently of passive crosslinkers such as fascin or fimbrin.

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Kools, W., Faour, S., Carlier, A., Hristova, T., Sirkia, M. E., Chaix, L., Lee, A., Martin, P., Houdusse, A., Romet-Lemonne, G., JEGOU, A.. 2026-09-11. Myosin-X sorts actin filaments into parallel bundles and tunes barbed-end dynamics. https://doi.org/10.64898/2026.09.08.749704

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