Septin 9 has Two Polybasic Domains Critical to Septin Filament Assembly and Golgi Integrity

Mohyeddine Omrane, Amanda Souza Camara, Cyntia Taveneau, Nassima Benzoubir, Thibault Tubiana, Jinchao Yu, Raphaël Guérois, Didier Samuel, Bruno Goud, Christian Poüs, Stéphane Bressanelli, Richard Charles Garratt, Abdou Rachid Thiam, Ama Gassama-Diagne

Research output: Contribution to journalArticleResearchpeer-review

19 Citations (Scopus)


Septins are GTP-binding proteins involved in several membrane remodeling mechanisms. They associate with membranes, presumably using a polybasic domain (PB1)that interacts with phosphoinositides (PIs). Membrane-bound septins assemble into microscopic structures that regulate membrane shape. How septins interact with PIs and then assemble and shape membranes is poorly understood. Here, we found that septin 9 has a second polybasic domain (PB2)conserved in the human septin family. Similar to PB1, PB2 binds specifically to PIs, and both domains are critical for septin filament formation. However, septin 9 membrane association is not dependent on these PB domains, but on putative PB-adjacent amphipathic helices. The presence of PB domains guarantees protein enrichment in PI-contained membranes, which is critical for PI-enriched organelles. In particular, we found that septin 9 PB domains control the assembly and functionality of the Golgi apparatus. Our findings offer further insight into the role of septins in organelle morphology.

Original languageEnglish
Pages (from-to)138-153
Number of pages16
Publication statusPublished - 29 Mar 2019
Externally publishedYes


  • Cell Biology
  • Functional Aspects of Cell Biology
  • Membrane Architecture
  • Molecular Interaction

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