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bioRxiv · 10.1101/2024.04.14.589463

Actin polymerization counteracts prewetting of N-WASP on supported lipid bilayers

Wiegand, T.·Liu, J.·Fritsch, A. W.·Vogeley, L.·Luvalle-Burke, I.·Geisler, J.·Hyman, A. A.·Grill, S. W.
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Abstract

Cortical condensates, transient punctate-like structures rich in actin and the actin nucleation pathway member N-WASP, form during activation of the actin cortex in the C. elegans oocyte. Their emergence and spontaneous dissolution is linked to a phase separation process driven by chemical kinetics. However, the physical process that drives the onset of cortical condensate formation near membranes remains unexplored. Here, using a reconstituted phase separation assay of cortical condensate proteins, we demonstrate that the key component, N-WASP, can collectively undergo surface condensation on supported lipid bilayers via a prewetting transition. Actin partitions into the condensates, where it polymerizes and counteracts the N-WASP prewetting transition. Taken together, the dynamics of condensate-assisted cortex formation appear to be controlled by a balance between surface-assisted condensate formation and polymer-driven condensate dissolution. This opens new perspectives for understanding how the formation of complex intracellular structures is affected and controlled by phase separation.

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Wiegand, T., Liu, J., Fritsch, A. W., Vogeley, L., Luvalle-Burke, I., Geisler, J., Hyman, A. A., Grill, S. W.. 2024-04-15. Actin polymerization counteracts prewetting of N-WASP on supported lipid bilayers. https://doi.org/10.1101/2024.04.14.589463

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