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

Francois Iv (1, 2) , Carla Silva Martins (1, 2) , Gerard Castro-Linares (3) , Cyntia Taveneau (4, 5) , Pascale Barbier (6) , Pascal Verdier-Pinard (7) , Luc Camoin (7) , Stéphane Audebert (7) , Feng-Ching Tsai (8) , Laurie Ramond (1, 2) , Alex Llewellyn (1, 2) , Mayssa Belhabib (1, 2) , Koyomi Nakazawa (4) , Aurelie Di Cicco (4) , Renaud Vincentelli (9) , Jérôme Wenger (1, 2) , Stéphanie Cabantous (10) , Gijsje Koenderink (3) , Aurélie Bertin (4) , Manos Mavrakis (2, 1)

1 FRESNEL - Institut FRESNEL
2 MOSAIC - MOSAIC
3 KI-NANO - Kavli Institute of Nanosciences [Delft]
4 PCC - Laboratoire Physico-Chimie Curie [Institut Curie]
5 Monash University [Clayton]
6 INP - Institut de neurophysiopathologie
7 CRCM - Centre de Recherche en Cancérologie de Marseille
8 AMOLF - FOM Institute for Atomic and Molecular Physics
9 AFMB - Architecture et fonction des macromolécules biologiques
10 CRCT - Centre de Recherches en Cancérologie de Toulouse

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. 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 the first-time 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/microtubule cytoskeleton.

Mots clés: Human septins; SEPT9 isoforms

Domaines: Organisation et fonctions cellulaires [q-bio.SC]; Biophysique; Interactions cellulaires [q-bio.CB]; Morphogenèse

Francois Iv, Carla Silva Martins, Gerard Castro-Linares, Cyntia Taveneau, Pascale Barbier, et al.. Insights into animal septins using recombinant human septin octamers with distinct SEPT9 isoforms. Journal of Cell Science, 2021, 134 (15), pp.jcs258484. ⟨10.1242/jcs.258484⟩. ⟨hal-03119193⟩