title: Effective killing of the human pathogen Candida albicans by a specific inhibitor of non-essential mitotic kinesin Kip1p.
abstract: Kinesins from the bipolar (Kinesin-5) family are conserved in eukaryotic organisms and play critical roles during the earliest stages of mitosis to mediate spindle pole body separation and formation of a bipolar mitotic spindle. To date, genes encoding bipolar kinesins have been reported to be essential in all organisms studied. We report the characterization of CaKip1p, the sole member of this family in the human pathogenic yeast Candida albicans. C. albicans Kip1p appears to localize to the mitotic spindle and loss of CaKip1p function interferes with normal progression through mitosis. Inducible excision of CaKIP1 revealed phenotypes unique to C. albicans, including viable homozygous Cakip1 mutants and an aberrant spindle morphology in which multiple spindle poles accumulate in close proximity to each other. Expression of the C. albicans Kip1 motor domain in Escherichia coli produced a protein with microtubule-stimulated ATPase activity that was inhibited by an aminobenzothiazole (ABT) compound in an ATP-competitive fashion. This inhibition results in 'rigor-like', tight association with microtubules in vitro. Upon treatment of C. albicans cells with the ABT compound, cells were killed, and terminal phenotype analysis revealed an aberrant spindle morphology similar to that induced by loss of the CaKIP1 gene. The ABT compound discovered is the first example of a fungal spindle inhibitor targeted to a mitotic kinesin. Our results also show that the non-essential nature and implementation of the bipolar motor in C. albicans differs from that seen in other organisms, and suggest that inhibitors of a non-essential mitotic kinesin may offer promise as cidal agents for antifungal drug discovery.
authors.affiliation: Cytokinetics, 280 East Grand Avenue, South San Francisco, CA 94080, USA. pchua@cytokinetics.com
authors.forename: Penelope R
authors.initials: PR
authors.lastname: Chua
authors.forename: David M
authors.initials: DM
authors.lastname: Roof
authors.forename: Yan
authors.initials: Y
authors.lastname: Lee
authors.forename: Roman
authors.initials: R
authors.lastname: Sakowicz
authors.forename: David
authors.initials: D
authors.lastname: Clarke
authors.forename: Dan
authors.initials: D
authors.lastname: Pierce
authors.forename: Thoryn
authors.initials: T
authors.lastname: Stephens
authors.forename: Matthew
authors.initials: M
authors.lastname: Hamilton
authors.forename: Brad
authors.initials: B
authors.lastname: Morgan
authors.forename: David
authors.initials: D
authors.lastname: Morgans
authors.forename: Takashi
authors.initials: T
authors.lastname: Nakai
authors.forename: Adam
authors.initials: A
authors.lastname: Tomasi
authors.forename: Mary E
authors.initials: ME
authors.lastname: Maxon
mesh_terms: D000251:Adenosine Triphosphatases / Q000032:analysis / Q000037:antagonists & inhibitors*; D000935:Antifungal Agents / Q000494:pharmacology*; D052160:Benzothiazoles / Q000494:pharmacology*; D002176:Candida albicans / Q000187:drug effects* / Q000201:enzymology; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D005656:Fungal Proteins / Q000032:analysis / Q000037:antagonists & inhibitors*; D016681:Genome, Fungal / Q000235:genetics; D006801:Humans; D008869:Microtubule-Associated Proteins / Q000032:analysis / Q000037:antagonists & inhibitors* / Q000235:genetics; D008938:Mitosis / Q000187:drug effects; D008941:Spindle Apparatus / Q000201:enzymology
chemical_list: D000935:Antifungal Agents; D052160:Benzothiazoles; D004791:Enzyme Inhibitors; D005656:Fungal Proteins; D008869:Microtubule-Associated Proteins; C523775:aminobenzothiazole compound; C087665:kinesin-like protein 1; D000251:Adenosine Triphosphatases