title: Identification of Saccharomyces cerevisiae Tub1 alpha-tubulin as a potential target for NKH-7, a cytotoxic 1-naphthol derivative compound.
abstract: In a screening for small-molecule compounds that alleviate the deleterious effects of external CaCl(2) on zds1 Delta strain yeast, we found 2-((1-(hydroxymethyl) cyclohexyl) methyl) naphthalen-1-ol (NKH-7) to be an active compound. NKH-7 also inhibited cell growth at higher concentrations. To identify its target in growth inhibition, we isolated NKH-7-resistant mutants and selected those mutants that exhibited dominant or semi-dominant resistance specifically to NKH-7. By gene cloning, a TUB1 mutant gene encoding alpha-tubulin with a Ser248Pro mutation was identified. Deletion of the TUB3 gene, a minor gene encoding alpha-tubulin, led to supersensitivity to NKH-7. Cellular tubulin-containing arrays as visualized by green fluorescent protein (GFP)-labeled alpha-tubulin diminished rapidly on exposure to the inhibitor. The mutation was situated proximal to the alpha-beta interface of alpha-tubulin in microtubule protofilaments, suggesting the possibility that NKH-7 affects the hydrolysis of GTP bound to beta-tubulin. A functional connection perhaps exists between the tubulin inhibition and Ca(2+)-dependent cell-cycle regulation.
authors.affiliation: Department of Molecular Biotechnology, Graduate School of Advanced Sciences of Matter, Hiroshima University, Higashi-Hiroshima 739-8530, Japan.
authors.forename: Ruthada
authors.initials: R
authors.lastname: Chanklan
authors.forename: Masaki
authors.initials: M
authors.lastname: Mizunuma
authors.forename: Ngampong
authors.initials: N
authors.lastname: Kongkathip
authors.forename: Komkrit
authors.initials: K
authors.lastname: Hasitapan
authors.forename: Boonsong
authors.initials: B
authors.lastname: Kongkathip
authors.forename: Tokichi
authors.initials: T
authors.lastname: Miyakawa
mesh_terms: D000483:Alleles; D002122:Calcium Chloride / Q000494:pharmacology; D048750:Cell Nucleus Division / Q000187:drug effects; D003603:Cytotoxins / Q000633:toxicity*; D004353:Drug Evaluation, Preclinical; D025141:Drug Resistance, Fungal / Q000235:genetics; D008870:Microtubules / Q000378:metabolism; D009154:Mutation; D009284:Naphthols / Q000737:chemistry / Q000633:toxicity*; D012441:Saccharomyces cerevisiae / Q000187:drug effects* / Q000235:genetics* / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics* / Q000378:metabolism*; D013379:Substrate Specificity; D014404:Tubulin / Q000235:genetics* / Q000378:metabolism*
chemical_list: C530419:2-((1-(hydroxymethyl)cyclohexyl)methyl)naphthalen-1-ol; D003603:Cytotoxins; D009284:Naphthols; D029701:Saccharomyces cerevisiae Proteins; C475498:Tub1 protein, S cerevisiae; D014404:Tubulin; D002122:Calcium Chloride