The Arabidopsis elch mutant reveals functions of an ESCRT component in cytokinesis.
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.
Spitzer
Christoph
C
University of Köln, Botanical Institute III, Gyrhofstr. 15, 50931 Köln, Germany.
Schellmann
Swen
S
Sabovljevic
Aneta
A
Shahriari
Mojgan
M
Keshavaiah
Channa
C
Bechtold
Nicole
N
Herzog
Michel
M
Müller
Stefan
S
Hanisch
Franz-Georg
FG
Hülskamp
Martin
M
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
D029681:Arabidopsis Proteins; D017931:DNA Primers; D018744:DNA, Plant; D046912:Multiprotein Complexes; D025801:Ubiquitin