title: Deletion mutants of AP-1 adaptin subunits display distinct phenotypes in fission yeast.
abstract: Adaptins are subunits of the heterotetrameric (beta/mu/gamma/sigma) adaptor protein (AP) complexes that are involved in clathrin-mediated membrane trafficking. Here, we show that in Schizosaccharomyces pombe the deletion strains of each individual subunit of the AP-1 complex [Apl2 (beta), Apl4 (gamma), Apm1 (mu) and Aps1 (sigma)] caused distinct phenotypes on growth sensitivity to temperature or drugs. We also show that the Deltaapm1 and Deltaapl2 mutants displayed similar but more severe phenotypes than those of Deltaaps1 or Deltaapl4 mutants. Furthermore, the Deltaapl2Deltaaps1 and Deltaapl2Deltaapl4 double mutants displayed synthetic growth defects, whereas the Deltaaps1Deltaapl4 and Deltaapl2Deltaapm1 double mutants did not. In pull-down assay, Apm1 binds Apl2 even in the absence of Aps1 and Apl4, and Apl4 binds Aps1 even in the absence of Apm1 and Apl2. Consistently, the deletion of any subunit generally caused the disassociation of the heterotetrameric complex from endosomes, although some subunits weakly localized to endosomes. In addition, the deletion of individual subunits caused similar endosomal accumulation of v-SNARE synaptobrevin Syb1. Altogether, results suggest that the four subunits are all essential for the heterotetrameric complex formation and for the AP-1 function in exit transport from endosomes.
authors.affiliation: Division of Molecular Pharmacology and Pharmacogenomics, Department of Biochemistry and Molecular Biology, Kobe University Graduate School of Medicine, Kusunoki-cho, Chuo-ku, Kobe 650-0017, Japan.
authors.forename: Yan
authors.initials: Y
authors.lastname: Ma
authors.forename: Mai
authors.initials: M
authors.lastname: Takeuchi
authors.forename: Reiko
authors.initials: R
authors.lastname: Sugiura
authors.forename: Susie O
authors.initials: SO
authors.lastname: Sio
authors.forename: Takayoshi
authors.initials: T
authors.lastname: Kuno
mesh_terms: D033961:Adaptor Protein Complex 1 / Q000235:genetics / Q000378:metabolism*; D034001:Adaptor Protein Complex Subunits / Q000235:genetics* / Q000378:metabolism*; D033966:Adaptor Protein Complex beta Subunits / Q000235:genetics / Q000378:metabolism; D033981:Adaptor Protein Complex delta Subunits / Q000235:genetics / Q000378:metabolism; D033983:Adaptor Protein Complex mu Subunits / Q000235:genetics / Q000378:metabolism; D034002:Adaptor Protein Complex sigma Subunits / Q000235:genetics / Q000378:metabolism; D000595:Amino Acid Sequence; D002462:Cell Membrane / Q000378:metabolism; D011992:Endosomes / Q000378:metabolism; D017353:Gene Deletion; D006056:Golgi Apparatus / Q000378:metabolism; D008969:Molecular Sequence Data; D010641:Phenotype; D012568:Schizosaccharomyces / Q000187:drug effects / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism; D029702:Schizosaccharomyces pombe Proteins / Q000235:genetics / Q000378:metabolism; D013696:Temperature; D014635:Valproic Acid / Q000494:pharmacology
chemical_list: D033961:Adaptor Protein Complex 1; D034001:Adaptor Protein Complex Subunits; D033966:Adaptor Protein Complex beta Subunits; D033981:Adaptor Protein Complex delta Subunits; D033983:Adaptor Protein Complex mu Subunits; D034002:Adaptor Protein Complex sigma Subunits; D029702:Schizosaccharomyces pombe Proteins; D014635:Valproic Acid