Insights into animal septins using recombinant human septin octamers with distinct SEPT9 isoforms

Francois Iv, Carla Silva Martins, Gerard Castro-Linares, Cyntia Taveneau, Pascale Barbier, Pascal Verdier-Pinard, Luc Camoin, Stéphane Audebert, Feng Ching Tsai, Laurie Ramond, Alex Llewellyn, Mayssa Belhabib, Koyomi Nakazawa, Aurélie Di Cicco, Renaud Vincentelli, Jerome Wenger, Stéphanie Cabantous, Gijsje H. Koenderink, Aurélie Bertin, Manos Mavrakis

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18 Citations (Scopus)


Septin GTP-binding proteins contribute essential biological functions that range from the establishment of cell polarity to animal tissue morphogenesis. Human septins in cells form hetero-octameric septin complexes containing the ubiquitously expressed SEPT9 subunit (also known as SEPTIN9). Despite the established role of SEPT9 in mammalian development and human pathophysiology, biochemical and biophysical studies have relied on monomeric SEPT9, thus not recapitulating its native assembly into hetero-octameric complexes. We established a protocol that enabled, for the first time, the isolation of recombinant human septin octamers containing distinct SEPT9 isoforms. A combination of biochemical and biophysical assays confirmed the octameric nature of the isolated complexes in solution. Reconstitution studies showed that octamers with either a long or a short SEPT9 isoform form filament assemblies, and can directly bind and cross-link actin filaments, raising the possibility that septin-decorated actin structures in cells reflect direct actin-septin interactions. Recombinant SEPT9-containing octamers will make it possible to design cell-free assays to dissect the complex interactions of septins with cell membranes and the actin and microtubule cytoskeleton.

Original languageEnglish
Article numberjcs258484
Number of pages19
JournalJournal of Cell Science
Issue number15
Publication statusPublished - 1 Aug 2021


  • In vitro reconstitution
  • Analytical ultracentrifugation
  • Cytoskeleton
  • Electron microscopy
  • Human septins
  • Mass spectrometry
  • Protein biochemistry
  • SEPT9 isoforms

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