Consequences of defective tubulin folding on heterodimer levels, mitosis and spindle morphology in Saccharomyces cerevisiae.

In budding yeast, the essential roles of microtubules include segregating chromosomes and positioning the nucleus during mitosis. Defects in these functions can lead to aneuploidy and cell death. To ensure proper mitotic spindle and cytoplasmic microtubule formation, the cell must maintain appropriate stoichiometries of alpha- and beta-tubulin, the basic subunits ...
of microtubules. The experiments described here investigate the minimal levels of tubulin heterodimers needed for mitotic function. We have found a triple-mutant strain, pac10Delta plp1Delta yap4Delta, which has only 20% of wild-type tubulin heterodimer levels due to synthesis and folding defects. The anaphase spindles in these cells are approximately 64% the length of wild-type spindles. The mutant cells are viable and accurately segregate chromosomes in mitosis, but they do have specific defects in mitosis such as abnormal nuclear positioning. The results establish that cells with 20% of wild-type levels of tubulin heterodimers can perform essential cellular functions with a short spindle, but require higher tubulin heterodimer concentrations to attain normal spindle length and prevent mitotic defects.
Mesh Terms:
Adaptor Proteins, Signal Transducing, Base Sequence, Chromosome Segregation, Chromosomes, Fungal, DNA, Fungal, Genes, Fungal, Lipoproteins, Membrane Proteins, Mitosis, Mitotic Spindle Apparatus, Mutation, Nuclear Proteins, Phenotype, Protein Folding, Protein Structure, Quaternary, RNA, Fungal, RNA, Messenger, Saccharomyces cerevisiae, Saccharomyces cerevisiae Proteins, Transcription Factors, Tubulin
Genetics
Date: Jun. 01, 2006
Download Curated Data For This Publication
69879
Switch View:
  • Interactions 2