Interplay of septin amphipathic helices in sensing membrane-curvature and filament bundling

© The Author(s), 2021. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Woods, B. L., Cannon, K. S., Vogt, E. J. D., Crutchley, J. M., & Gladfelter, A. S. Interplay of septin amphipathic helices in sensing membrane-curvature and filament bundling. Molecular Biology of the Cell, 32(20), (2021): mbcE20050303, https://doi.org/10.1091/mbc.E20-05-0303.The curvature of the membrane defines cell shape. Septins are GTP-binding proteins that assemble into heteromeric complexes and polymerize into filaments at areas of micron-scale membrane curvature. An amphipathic helix (AH) domain within the septin complex is necessary and sufficient for septins to preferentially assemble onto micron-scale curvature. Here we report that the nonessential fungal septin, Shs1, also has an AH domain capable of recognizing membrane curvature. In a septin mutant strain lacking a fully functional Cdc12 AH domain (cdc12-6), the C-terminal extension of Shs1, containing an AH domain, becomes essential. Additionally, we find that the Cdc12 AH domain is important for regulating septin filament bundling, suggesting septin AH domains have multiple, distinct functions and that bundling and membrane binding may be coordinately controlled.This work was supported by National Institutes of Health (NIH) Grant no. R01GM-130934 to A.S.G. B.L.W. was supported by the NIH Training Grant no. 2T32AI052080-16. K.S.C. and E.J.D.V. were supported in part by a grant from the National Institute of General Medical Sciences under award T32 GM119999