A novel factor required for the SUMO1/Smt3 conjugation of yeast septins

Gene. 2001 Sep 19;275(2):223-31. doi: 10.1016/s0378-1119(01)00662-x.

Abstract

SUMO1/Smt3, a ubiquitin-like protein modifier, is known to be conjugated to other proteins and modulate their functions in various important processes. Similar to the ubiquitin system, SUMO1/Smt3 is activated in an ATP-dependent reaction by thioester bond formation with E1 (activating enzyme), transferred to E2 (conjugating enzyme), and passed to a substrate lysine. It remained unknown, however, whether any SUMO1/Smt3 ligases (E3s) are involved in the final transfer of this modifier. Here we report a novel factor Siz1 (YDR409w) required for septin-sumoylation of budding yeast, possibly acting as E3. Siz1 is a member of a new family (Miz1, PIAS3, etc.) containing a conserved domain with a similarity to a zinc-binding RING-domain, often found in ubiquitin ligases. In the siz1 mutant septin-sumoylation was completely abolished. A conserved cysteine residue in the domain was essential for this conjugation. Furthermore, Siz1 was localized at the mother-bud neck in the M-phase and physically bound to both E2 and the target proteins.

MeSH terms

  • Amino Acid Sequence
  • Cell Cycle Proteins / genetics
  • Cell Cycle Proteins / metabolism
  • Electrophoretic Mobility Shift Assay
  • Fluorescent Antibody Technique, Indirect
  • Fungal Proteins / genetics
  • Fungal Proteins / metabolism*
  • Green Fluorescent Proteins
  • Indoles
  • Ligases / genetics
  • Ligases / metabolism
  • Luminescent Proteins / genetics
  • Luminescent Proteins / metabolism
  • Microscopy, Fluorescence
  • Mitosis
  • Molecular Sequence Data
  • Phosphorylation
  • Profilins
  • Protein Binding
  • Recombinant Fusion Proteins / genetics
  • Recombinant Fusion Proteins / metabolism
  • SUMO-1 Protein / genetics
  • SUMO-1 Protein / metabolism*
  • Saccharomyces cerevisiae / genetics
  • Saccharomyces cerevisiae / metabolism
  • Saccharomyces cerevisiae Proteins*
  • Sequence Homology, Amino Acid
  • Two-Hybrid System Techniques
  • Ubiquitin-Conjugating Enzymes*
  • Zinc Fingers / genetics

Substances

  • CDC3 protein, S cerevisiae
  • Cell Cycle Proteins
  • Fungal Proteins
  • Indoles
  • Luminescent Proteins
  • PCD1 protein, Pyrenopeziza brassicae
  • Profilins
  • Recombinant Fusion Proteins
  • SUMO-1 Protein
  • Saccharomyces cerevisiae Proteins
  • Green Fluorescent Proteins
  • DAPI
  • Ubiquitin-Conjugating Enzymes
  • Ligases
  • ubiquitin-conjugating enzyme UBC9