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bioRxiv · 10.1101/2022.07.22.501094

Impact of native-like lipid membranes on the architecture and contractility of actomyosin networks

Liebe, N. L.·Mey, I.·Vuong, L.·Geil, B.·Janshoff, A.·Steinem, C.
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Abstract

The connection between the actomyosin cortex and the plasma membrane of eukaryotic cells is investigated by creating a versatile, near-native model system that allows studying the architecture and contractility of the cortex as a function of lipid composition. We found that the concentration of phosphatidylserine, a characteristic lipid of the inner leaflet of mammalian plasma membranes, plays a pivotal role in the binding of the membrane-cytoskeleton linker protein ezrin and the resulting contractile behavior of an adjacent actin network. In addition to the specific receptor lipid for ezrin, i.e., PtdIns[4,5]P2 cross-linking the network to the inner leaflet, the presence of phosphatidylserine in the membrane is critical to enhancing the binding of ezrin to PtdIns[4,5]P2 and allows rapid local actin contraction at physiologically relevant concentrations in the regime of 1-3 mol% PtdIns[4,5]P2. In the presence of phosphatidylserine, the additional negative charges in the membrane may induce enhanced sliding of the filaments on the membrane surface due to repulsive interactions between F-actin and the bilayer readily leading to the emergence of contraction foci. Conversely, if phosphatidylserine is replaced by an increased PtdIns[4,5]P2 concentration of 5 or 8 mol%, a highly connected but non-contracting actin network is observed.

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Liebe, N. L., Mey, I., Vuong, L., Geil, B., Janshoff, A., Steinem, C.. 2022-07-22. Impact of native-like lipid membranes on the architecture and contractility of actomyosin networks. https://doi.org/10.1101/2022.07.22.501094

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