RRC ID 2162
Author Tange Y, Niwa O.
Title Novel mad2 alleles isolated in a Schizosaccharomyces pombe gamma-tubulin mutant are defective in metaphase arrest activity, but remain functional for chromosome stability in unperturbed mitosis.
Journal Genetics
Abstract A previously isolated fission yeast gamma-tubulin mutant containing apparently stabilized microtubules proliferated at an approximately identical rate as wild type, yet the mutant mitosis spindle dynamics were aberrant, particularly the kinetochore microtubule dynamics. Progression through mitosis in the mutant, however, resulted in mostly accurate chromosome segregation. In the absence of the spindle assembly checkpoint gene, mad2+, the spindle dynamics in the gamma-tubulin mutant were greatly compromised, leading to a high incidence of chromosome missegregation. Unlike in wild-type cells, green fluorescent protein (GFP)-tagged Mad2 protein often accumulated near one of the poles of an elongating spindle in the gamma-tubulin mutant. We isolated novel mad2 mutants that were defective in arresting mitotic progression upon gross perturbation of the spindle formation but remained functional for the viability of the gamma-tubulin mutant. Further, the mad2 mutations did not appreciably destabilize minichromosomes in unperturbed mitoses. When overexpressed ectopically, these mutant Mad2 proteins sequestered wild-type Mad2, preventing its function in mitotic checkpoint arrest, but not in minichromosome stability. These results indicated that the Mad2 functions required for checkpoint arrest and chromosome stability in unperturbed mitosis are genetically discernible. Immunoprecipitation studies demonstrated that GFP-fused mutant Mad2 proteins formed a Mad1-containing complex with altered stability compared to that formed with wild-type Mad2, providing clues to the novel mad2 mutant phenotype.
Volume 175(4)
Pages 1571-84
Published 2007-4
DOI 10.1534/genetics.106.061309
PII genetics.106.061309
PMID 17277378
PMC PMC1855100
MeSH Alleles Anaphase / genetics Cell Cycle Proteins / genetics* Cell Cycle Proteins / metabolism* Chromosomal Instability Chromosome Segregation / genetics Chromosomes, Fungal / genetics Gene Expression Genes, Fungal Green Fluorescent Proteins / genetics Green Fluorescent Proteins / metabolism Mad2 Proteins Metaphase / genetics Mitosis / genetics Mutation Nuclear Proteins / genetics* Nuclear Proteins / metabolism* Recombinant Fusion Proteins / genetics Recombinant Fusion Proteins / metabolism Schizosaccharomyces / genetics* Schizosaccharomyces / metabolism* Schizosaccharomyces pombe Proteins / genetics* Schizosaccharomyces pombe Proteins / metabolism* Spindle Apparatus / metabolism Tubulin / genetics* Tubulin / metabolism*
IF 3.564
Times Cited 6
Yeast cdc13GFP? FY16055(HM783)