An amphipathic helix enables septins to sense micrometer-scale membrane curvature
Cannon, Kevin S.
Woods, Benjamin L.
Crutchley, John M.
Gladfelter, Amy S.
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Cell shape is well described by membrane curvature. Septins are filament-forming, GTP-binding proteins that assemble on positive, micrometer-scale curvatures. Here, we examine the molecular basis of curvature sensing by septins. We show that differences in affinity and the number of binding sites drive curvature-specific adsorption of septins. Moreover, we find septin assembly onto curved membranes is cooperative and show that geometry influences higher-order arrangement of septin filaments. Although septins must form polymers to stay associated with membranes, septin filaments do not have to span micrometers in length to sense curvature, as we find that single-septin complexes have curvature-dependent association rates. We trace this ability to an amphipathic helix (AH) located on the C-terminus of Cdc12. The AH domain is necessary and sufficient for curvature sensing both in vitro and in vivo. These data show that curvature sensing by septins operates at much smaller length scales than the micrometer curvatures being detected.
© The Authors, 2019. This article is distributed under the terms of the Creative Commons Attribution-Noncommercial-Share Alike 4.0 International License. The definitive version was published in Journal of Cell Biology (2019), doi:10.1083/jcb.201807211.
Suggested CitationCannon, K. S., Woods, B. L., Crutchley, J. M., & Gladfelter, A. S. (2019). An amphipathic helix enables septins to sense micrometer-scale membrane curvature. Journal of Cell Biology, jcb.201807211.
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