title: A role of Sep1 (= Kem1, Xrn1) as a microtubule-associated protein in Saccharomyces cerevisiae.
abstract: Saccharomyces cerevisiae cells lacking the SEP1 (also known as XRN1, KEM1, DST2, RAR5) gene function exhibit a number of phenotypes in cellular processes related to microtubule function. Mutant cells show increased sensitivity to the microtubule-destabilizing drug benomyl, increased chromosome loss, a karyogamy defect, impaired spindle pole body separation, and defective nuclear migration towards the bud neck. Analysis of the arrest morphology and of the survival during arrest strongly suggests a structural defect accounting for the benomyl hypersensitivity, rather than a regulatory defect in a checkpoint. Biochemical analysis of the purified Sep1 protein demonstrates its ability to promote the polymerization of procine brain and authentic S.cerevisiae tubulin into flexible microtubules in vitro. Furthermore, Sep1 co-sediments with these microtubules in sucrose cushion centrifugation. Genetic analysis of double mutant strains containing a mutation in SEP1 and in one of the genes coding for alpha- or beta-tubulin further suggests interaction between Sep1 and microtubules. Taken together these three lines of evidence constitute compelling evidence for a role of Sep1 as an accessory protein in microtubule function in the yeast S.cerevisiae.
authors.affiliation: Institute of General Microbiology, University of Bern, Switzerland.
authors.forename: H
authors.initials: H
authors.lastname: Interthal
authors.forename: C
authors.initials: C
authors.lastname: Bellocq
authors.forename: J
authors.initials: J
authors.lastname: Bähler
authors.forename: V I
authors.initials: VI
authors.lastname: Bashkirov
authors.forename: S
authors.initials: S
authors.lastname: Edelstein
authors.forename: W D
authors.initials: WD
authors.lastname: Heyer
mesh_terms: D000818:Animals; D001542:Benomyl / Q000494:pharmacology; D001923:Brain Chemistry; D002455:Cell Division / Q000187:drug effects / Q000502:physiology; D002467:Cell Nucleus / Q000502:physiology; D004252:DNA Mutational Analysis; D003851:Deoxyribonucleases / Q000235:genetics / Q000302:isolation & purification / Q000502:physiology*; D004843:Epistasis, Genetic; D005095:Exoribonucleases; D005656:Fungal Proteins / Q000235:genetics / Q000302:isolation & purification / Q000502:physiology*; D005800:Genes, Fungal / Q000235:genetics; D008869:Microtubule-Associated Proteins / Q000235:genetics / Q000302:isolation & purification / Q000502:physiology*; D008870:Microtubules / Q000187:drug effects / Q000502:physiology* / Q000648:ultrastructure; D015739:Nocodazole / Q000494:pharmacology; D012441:Saccharomyces cerevisiae / Q000166:cytology*; D029701:Saccharomyces cerevisiae Proteins; D008941:Spindle Apparatus; D013552:Swine; D014404:Tubulin / Q000096:biosynthesis / Q000235:genetics
chemical_list: D005656:Fungal Proteins; D008869:Microtubule-Associated Proteins; D029701:Saccharomyces cerevisiae Proteins; D014404:Tubulin; D003851:Deoxyribonucleases; D005095:Exoribonucleases; C068398:XRN1 protein, S cerevisiae; D015739:Nocodazole; D001542:Benomyl