The fission yeast γ-tubulin is essential for mitosis and is localized at microtubule organizing centers

Abstract

γ-Tubulin exists in fission yeast as the product of an essential gene, encoding a 446 amino acid protein that is 77.3% identical to Aspergillus nidulans γ-tubulin. The gene disruption caused cell lethality, displaying condensed, undivided chromosomes with aberrant spindle structures. Anti-γ-tubulin staining showed that γ-tubulin is located, throughout the wild-type cell cycle, at the spindle pole bodies (SPBs), indicating that γ-tubulin associates with interphase SPB in the absence of microtubules. In addition, anti-γ-tubulin immunofluorescence staining revealed cytoplasmic, cell-equatorial putative MTOCs (microtubule organizing centers), which appear only during mitotic telophase and cytokinesis, and are located at the centers for the new cytoplasmic microtubule arrays of the two daughter cells. In the multiple-SPB mutant cutl-cdcll, anti-γ-tubulin antibodies revealed many dots on the periphery of the nucleus. These results confirm that γ-tubulin is an important member of the tubulin superfamily, suggest that it may be a universal component of MTOCs, and are consistent with a role for γ-tubulin in controlling microtubule formation in vivo.