biostudies-literatureUnknownCurtis BNNICHD NIH HHSNINDS NIH HHSNIGMS NIH HHSSeptins assemble into scaffolds that direct cell growth and morphology that are often localized to the plasma membrane. While septins preferentially bind convex membranes via amphipathic helices, their assembly on varied geometries in cells suggests additional localization cues. We tested the hypothesis that lipid composition directs septin assembly through lipid packing properties. Lipid mixtures varying in lipid packing were designed by molecular dynamics simulations and incorporated onto supported lipid bilayers to measure septin adsorption in vitro. Septins strongly favor loosely-packed, disordered lipid bilayers but additional geometry cues act in conjunction with this membrane property. Introducing tighter lipid packing in cells disrupted septin structures in a curvature dependent manner, specifically limiting septin assembly and retention along flat regions of the plasma membrane. This work demonstrates that packing defects and geometry jointly regulate septin localization and highlights how multiple membrane properties are integrated to control organization of the septin cytoskeleton.bioRxiv : the preprint server for biology2025.02.12.637894https://www.ebi.ac.uk/biostudies/studies/S-EPMC11844530biostudies-literatureLipid packing and local geometry influence septin curvature sensing.PMC11844530R01 GM130934F31 GM151820P50 HD103573P30 NS045892T32 GM119999Gladfelter ASEdelmaier CCurtis BNVogt EJDfalseLipid packing and local geometry influence septin curvature sensing.Septins assemble into scaffolds that direct cell growth and morphology that are often localized to the plasma membrane. While septins preferentially bind convex membranes via amphipathic helices, their assembly on varied geometries in cells suggests additional localization cues. We tested the hypothesis that lipid composition directs septin assembly through lipid packing properties. Lipid mixtures varying in lipid packing were designed by molecular dynamics simulations and incorporated onto supported lipid bilayers to measure septin adsorption in vitro. Septins strongly favor loosely-packed, disordered lipid bilayers but additional geometry cues act in conjunction with this membrane property. Introducing tighter lipid packing in cells disrupted septin structures in a curvature dependent manner, specifically limiting septin assembly and retention along flat regions of the plasma membrane. This work demonstrates that packing defects and geometry jointly regulate septin localization and highlights how multiple membrane properties are integrated to control organization of the septin cytoskeleton.2025-01-01T00:00:00Z2025 Feb2026-05-22T03:18:43.865Z2025-04-04T02:12:12.061ZS-EPMC118445303999047910.1101/2025.02.12.637894