title: A novel factor required for the SUMO1/Smt3 conjugation of yeast septins.
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.
authors.affiliation: Department of Biological Sciences, Graduate School of Science, The University of Tokyo, 7-3-1, Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Takahashi
authors.forename: A
authors.initials: A
authors.lastname: Toh-e
authors.forename: Y
authors.initials: Y
authors.lastname: Kikuchi
mesh_terms: D000595:Amino Acid Sequence; D018797:Cell Cycle Proteins / Q000235:genetics / Q000378:metabolism; D024202:Electrophoretic Mobility Shift Assay; D019084:Fluorescent Antibody Technique, Indirect; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism*; D049452:Green Fluorescent Proteins; D007211:Indoles; D008025:Ligases / Q000235:genetics / Q000378:metabolism; D008164:Luminescent Proteins / Q000235:genetics / Q000378:metabolism; D008856:Microscopy, Fluorescence; D008938:Mitosis; D008969:Molecular Sequence Data; D010766:Phosphorylation; D051304:Profilins; D011485:Protein Binding; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D025842:SUMO-1 Protein / Q000235:genetics / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins; D017386:Sequence Homology, Amino Acid; D020798:Two-Hybrid System Techniques; D044763:Ubiquitin-Conjugating Enzymes; D016335:Zinc Fingers / Q000235:genetics; D000098843:Ubiquitin-Conjugating Enzyme UBC9
chemical_list: C086662:CDC3 protein, S cerevisiae; D018797:Cell Cycle Proteins; D005656:Fungal Proteins; D007211:Indoles; D008164:Luminescent Proteins; C410684:PCD1 protein, Pyrenopeziza brassicae; D051304:Profilins; D011993:Recombinant Fusion Proteins; D025842:SUMO-1 Protein; D029701:Saccharomyces cerevisiae Proteins; D049452:Green Fluorescent Proteins; C007293:DAPI; D044763:Ubiquitin-Conjugating Enzymes; D008025:Ligases; D000098843:Ubiquitin-Conjugating Enzyme UBC9