Septin stability and recycling during dynamic structural transitions in cell division and development

Curr Biol. 2008 Aug 26;18(16):1203-8. doi: 10.1016/j.cub.2008.07.020. Epub 2008 Aug 14.

Abstract

Septins are conserved proteins found in hetero-oligomeric complexes that are incorporated into distinct structures during cell division and differentiation; yeast septins Cdc3, Cdc10, Cdc11, and Cdc12 form hetero-octamers and polymerize into filaments, which form a "collar" at the mother-bud neck [1]. Posttranslational modifications, nucleotide binding, and protein-protein and protein-lipid interactions influence assembly and disassembly of septin structures [2], but whether individual septins are used repeatedly to build higher-order assemblies was not known. We used fluorescence-based pulse-chase methods to visualize the fate of pre-existing (old) and newly synthesized (new) molecules of two septins, Cdc10 and Cdc12. They were recycled through multiple mitotic divisions, and old and new molecules were incorporated indistinguishably into the collar. Likewise, old and new subunits intermixed within hetero-octamers, indicating that exchange occurs at this organizational level. Remarkably, in meiosis, Cdc10 made during vegetative growth was reutilized to build sporulation-specific structures and reused again during spore germination for budding and during subsequent mitotic divisions. Although Cdc12 also persisted during sporulation, it was excluded from septin structures and replaced by another subunit, Spr3; only new Cdc12 populated the collar of germinating spores. Thus, mechanisms governing septin incorporation are specific to each subunit and to the developmental state of the cell.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Cell Cycle Proteins / genetics
  • Cell Cycle Proteins / metabolism*
  • Cell Division*
  • Cytoskeletal Proteins / genetics
  • Cytoskeletal Proteins / metabolism*
  • GTP Phosphohydrolases / genetics
  • GTP Phosphohydrolases / metabolism*
  • Humans
  • Membrane Proteins / genetics
  • Membrane Proteins / metabolism*
  • Multiprotein Complexes / metabolism
  • O(6)-Methylguanine-DNA Methyltransferase / genetics
  • O(6)-Methylguanine-DNA Methyltransferase / metabolism
  • Saccharomyces cerevisiae / growth & development
  • Saccharomyces cerevisiae / metabolism*
  • Saccharomyces cerevisiae Proteins / genetics
  • Saccharomyces cerevisiae Proteins / metabolism*
  • Spores, Fungal / growth & development

Substances

  • CDC12 protein, S cerevisiae
  • Cell Cycle Proteins
  • Cytoskeletal Proteins
  • Membrane Proteins
  • Multiprotein Complexes
  • Saccharomyces cerevisiae Proteins
  • O(6)-Methylguanine-DNA Methyltransferase
  • CDC10 protein, S cerevisiae
  • GTP Phosphohydrolases