title: The Arabidopsis elch mutant reveals functions of an ESCRT component in cytokinesis.
abstract: Recently, an alternative route to the proteasomal protein-degradation pathway was discovered that specifically targets transmembrane proteins marked with a single ubiquitin to the endosomal multivesicular body (MVB) and, subsequently, to the vacuole (yeast) or lysosome (animals), where they are degraded by proteases. Vps23p/TSG101 is a key component of the ESCRT I-III machinery in yeast and animals that recognizes mono-ubiquitylated proteins and sorts them into the MVB. Here, we report that the Arabidopsis ELCH (ELC) gene encodes a Vps23p/TSG101 homolog, and that homologs of all known ESCRT I-III components are present in the Arabidopsis genome. As with its animal and yeast counterparts, ELC binds ubiquitin and localizes to endosomes. Gel-filtration experiments indicate that ELC is a component of a high-molecular-weight complex. Yeast two-hybrid and immunoprecipitation assays showed that ELC interacts with Arabidopsis homologs of the ESCRT I complex. The elc mutant shows multiple nuclei in various cell types, indicating a role in cytokinesis. Double-mutant analysis with kaktus shows that increased ploidy levels do not influence the cytokinesis effect of elc mutants, suggesting that ELC is only important during the first endoreduplication cycle. Double mutants with tubulin folding cofactor a mutants show a synergistic phenotype, suggesting that ELC regulates cytokinesis through the microtubule cytoskeleton.
authors.affiliation: University of Köln, Botanical Institute III, Gyrhofstr. 15, 50931 Köln, Germany.
authors.forename: Christoph
authors.initials: C
authors.lastname: Spitzer
authors.forename: Swen
authors.initials: S
authors.lastname: Schellmann
authors.forename: Aneta
authors.initials: A
authors.lastname: Sabovljevic
authors.forename: Mojgan
authors.initials: M
authors.lastname: Shahriari
authors.forename: Channa
authors.initials: C
authors.lastname: Keshavaiah
authors.forename: Nicole
authors.initials: N
authors.lastname: Bechtold
authors.forename: Michel
authors.initials: M
authors.lastname: Herzog
authors.forename: Stefan
authors.initials: S
authors.lastname: Müller
authors.forename: Franz-Georg
authors.initials: FG
authors.lastname: Hanisch
authors.forename: Martin
authors.initials: M
authors.lastname: Hülskamp
mesh_terms: D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000166:cytology / Q000235:genetics* / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D001483:Base Sequence; D017124:Conserved Sequence; D048749:Cytokinesis / Q000235:genetics / Q000502:physiology; D003599:Cytoskeleton / Q000378:metabolism; D017931:DNA Primers / Q000235:genetics; D018744:DNA, Plant / Q000235:genetics; D011992:Endosomes / Q000378:metabolism; D017343:Genes, Plant; D008870:Microtubules / Q000378:metabolism; D008969:Molecular Sequence Data; D046912:Multiprotein Complexes; D009154:Mutation; D010641:Phenotype; D030821:Plants, Genetically Modified; D017386:Sequence Homology, Amino Acid; D025801:Ubiquitin / Q000378:metabolism
chemical_list: D029681:Arabidopsis Proteins; D017931:DNA Primers; D018744:DNA, Plant; D046912:Multiprotein Complexes; D025801:Ubiquitin