Phosphatidylinositol polyphosphate binding to the mammalian septin H5 is modulated by GTP

Curr Biol. 1999 Dec 16-30;9(24):1458-67. doi: 10.1016/s0960-9822(00)80115-3.


Background: Septins are members of a conserved family of GTPases found in organisms as diverse as budding yeast and mammals. In budding yeast, septins form hetero-oligomeric filaments that lie adjacent to the membrane at the mother-bud neck, whereas in mammals, they concentrate at the cleavage furrow of mitotic cells; in both cases, septins provide a required function for cytokinesis. What directs the location and determines the stability of septin filaments, however, remains unknown.

Results: Here we show that the mammalian septin H5 is associated with the plasma membrane and specifically binds the phospholipids phosphatidylinositol 4, 5-bisphosphate (PtdIns(4,5)P(2)) and phosphatidylinositol 3,4, 5-trisphosphate (PtdIns(3,4,5)P(3)). Deletion analysis revealed that this binding occurs at a site rich in basic residues that is conserved in most septins and is located adjacent to the GTP-binding motif. Phosphoinositide binding was inhibited by mutations within this motif and was also blocked by agents known to associate with PtdInsP(2) or by a peptide corresponding to the predicted PtdInsP(2)-binding sequence of H5. GTP binding and hydrolysis by H5 significantly reduced its PtdInsP(2)-binding capability. Treatment of cells with agents that occluded, dephosphorylated or degraded PtdInsP(2) altered the appearance and localization of H5.

Conclusions: These results indicate that the interaction of septins with PtdInsP(2) might be an important cellular mechanism for the spatial and temporal control of septin accumulation.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • 3T3 Cells
  • Amino Acid Sequence
  • Animals
  • Binding Sites / genetics
  • Cytoskeletal Proteins / chemistry
  • Cytoskeletal Proteins / genetics
  • Cytoskeletal Proteins / metabolism*
  • GTP Phosphohydrolases / chemistry
  • GTP Phosphohydrolases / genetics
  • GTP Phosphohydrolases / metabolism*
  • Guanosine Triphosphate / metabolism*
  • Ionomycin / pharmacology
  • Mice
  • Molecular Sequence Data
  • Mutagenesis, Site-Directed
  • Neomycin / pharmacology
  • Nerve Tissue Proteins / genetics
  • Nerve Tissue Proteins / metabolism
  • Phosphatidylinositol 4,5-Diphosphate / metabolism*
  • Phosphatidylinositol Phosphates / metabolism*
  • Phosphoric Monoester Hydrolases / genetics
  • Phosphoric Monoester Hydrolases / metabolism
  • Protein Binding
  • Septins
  • Sequence Homology, Amino Acid


  • Cytoskeletal Proteins
  • Nerve Tissue Proteins
  • Phosphatidylinositol 4,5-Diphosphate
  • Phosphatidylinositol Phosphates
  • phosphatidylinositol 3,4,5-triphosphate
  • Ionomycin
  • Guanosine Triphosphate
  • synaptojanin
  • Phosphoric Monoester Hydrolases
  • GTP Phosphohydrolases
  • Sept4 protein, mouse
  • Septins
  • Neomycin