Consequences of defective tubulin folding on heterodimer levels, mitosis, and spindle morphology in S. 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 - and -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, pac10 plp1 yap4, which has only 20% of wild type tubulin heterodimer levels due to synthesis and folding defects. The anaphase spindles in these cells are ~ 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.

Key Words: microtubules, mitosis, protein folding, spindle assembly, tubulin

This article has been cited by other articles:

				E. M. Torres, B. R. Williams, and A. Amon Aneuploidy: Cells Losing Their Balance Genetics, June 1, 2008; 179(2): 737 - 746. [Abstract] [Full Text] [PDF]

				M. M. Castellano and R. Sablowski Phosducin-Like Protein 3 Is Required for Microtubule-Dependent Steps of Cell Division but Not for Meristem Growth in Arabidopsis PLANT CELL, April 1, 2008; 20(4): 969 - 981. [Abstract] [Full Text] [PDF]

Online ISS 1091-6490
Copyright 2008 by the Genetics Society of America
phone: 412-268-1812   fax: 412-268-1813   email: genetics-gsa{at}andrew.cmu.edu