title: A putative endosomal t-SNARE links exo- and endocytosis in the phytopathogenic fungus Ustilago maydis.
abstract: We identified a temperature-sensitive mutant of the plant pathogenic fungus Ustilago maydis that is defective in the polar distribution of cell wall components and shows abnormal morphology. The affected gene, yup1, was cloned by complementation. It encodes a putative target soluble N-ethylmaleimide-sensitive fusion protein attachment protein receptor (t-SNARE), suggesting a function in membrane fusion. A Yup1-GFP fusion protein localized to vesicles that showed rapid saltatory motion along microtubules. These vesicles are part of the endocytic pathway and accumulate at sites of active growth, thereby supporting the expansion of the hyphal tip. In yup1(ts) cells, endocytosis is impaired and accumulation of Yup1-carrying endosomes at cell poles is abolished, resulting in apolar distribution of wall components and morphological alterations. This suggests that a membrane recycling process via early endosomes supports polar growth of U. maydis.
authors.affiliation: Institut für Genetik und Mikrobiologie, LMU, Maria-Ward-Strasse 1a, D-80638 München, Germany.
authors.forename: R
authors.initials: R
authors.lastname: Wedlich-Söldner
authors.forename: M
authors.initials: M
authors.lastname: Bölker
authors.forename: R
authors.initials: R
authors.lastname: Kahmann
authors.forename: G
authors.initials: G
authors.lastname: Steinberg
mesh_terms: D000595:Amino Acid Sequence; D016764:Cell Polarity; D002473:Cell Wall / Q000737:chemistry / Q000378:metabolism; D003001:Cloning, Molecular; D004705:Endocytosis; D011992:Endosomes / Q000737:chemistry* / Q000378:metabolism; D005033:Ethylmaleimide / Q000494:pharmacology; D005089:Exocytosis; D005656:Fungal Proteins / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D005800:Genes, Fungal / Q000235:genetics; D005816:Genetic Complementation Test; D008561:Membrane Fusion; D008565:Membrane Proteins / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D008870:Microtubules / Q000378:metabolism; D008954:Models, Biological; D008969:Molecular Sequence Data; D009024:Morphogenesis / Q000235:genetics; D009154:Mutation / Q000235:genetics; D010802:Phylogeny; D017434:Protein Structure, Tertiary; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D050600:SNARE Proteins; D016415:Sequence Alignment; D013696:Temperature; D014588:Ustilago / Q000166:cytology / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D033921:Vesicular Transport Proteins
chemical_list: D005656:Fungal Proteins; D008565:Membrane Proteins; D011993:Recombinant Fusion Proteins; D050600:SNARE Proteins; D033921:Vesicular Transport Proteins; C409262:Yup1 protein, Ustilago maydis; D005033:Ethylmaleimide