Human gamma-tubulin functions in fission yeast.
gamma-Tubulin is a phylogenetically conserved component of microtubule-organizing centers that is essential for viability and microtubule function. To examine the functional conservation of gamma-tubulin, we have tested the ability of human gamma-tubulin to function in the fission yeast Schizosaccharomyces pombe. We have found that expression of a human gamma-tubulin cDNA restores viability and a near-normal growth rate to cells of S. pombe lacking endogenous gamma-tubulin. Immunofluorescence microscopy showed that these cells contained normal mitotic spindles and interphase microtubule arrays, and that human gamma-tubulin, like S. pombe gamma-tubulin, localized to spindle pole bodies, the fungal microtubule-organizing centers. These results demonstrate that human gamma-tubulin functions in fission yeast, and they suggest that in spite of the great morphological differences between the microtubule-organizing centers of humans and fission yeasts, gamma-tubulin is likely to perform the same tasks in both. They suggest, moreover, that the proteins that interact with gamma-tubulin, including, most obviously, microtubule-organizing center proteins, must also be conserved. We have also found that a fivefold overexpression of S. pombe gamma-tubulin causes no reduction in growth rates or alteration of microtubule organization. We hypothesize that the excess gamma-tubulin is maintained in the cytoplasm in a form incapable of nucleating microtubule assembly. Finally, we have found that expression of human gamma-tubulin or overexpression of S. pombe gamma-tubulin causes no significant alteration of resistance to the antimicrotubule agents benomyl, thiabendazole and nocodazole.
Horio
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Department of Molecular Genetics, Ohio State University, Columbus 43210.
Oakley
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BR
D004352:Drug Resistance, Microbial / Q000502:physiology; D006801:Humans; D008870:Microtubules / Q000187:drug effects / Q000502:physiology*; D015388:Organelles / Q000737:chemistry*; D011994:Recombinant Proteins; D012568:Schizosaccharomyces / Q000187:drug effects / Q000254:growth & development / Q000502:physiology / Q000648:ultrastructure*; D013045:Species Specificity; D008941:Spindle Apparatus / Q000737:chemistry; D014404:Tubulin / Q000032:analysis / Q000096:biosynthesis / Q000502:physiology*
D011994:Recombinant Proteins; D014404:Tubulin