Fission yeast mtr1p regulates interphase microtubule cortical dwell-time.

The microtubule cytoskeleton plays important roles in cell polarity, motility and division. Microtubules inherently undergo dynamic instability, stochastically switching between phases of growth and shrinkage. In cells, some microtubule-associated proteins (MAPs) and molecular motors can further modulate microtubule dynamics. We present here the fission yeast mtr1 + , a new regulator of microtubule dynamics that appears to be not a MAP or a motor. mtr1-deletion (mtr1D) primarily results in longer microtubule dwelltime at the cell tip cortex, suggesting that mtr1p acts directly or indirectly as a destabilizer of microtubules. mtr1p is antagonistic to mal3p, the ortholog of mammalian EB1, which stabilizes microtubules. mal3D results in short microtubules, but can be partially rescued by mtr1D, as the double mutant mal3D mtr1D exhibits longer microtubules than mal3D single mutant. By sequence homology, mtr1p is predicted to be a component of the ribosomal quality control complex. Intriguingly, deletion of a predicted ribosomal gene, rps1801, also resulted in longer microtubule dwell-time similar to mtr1D. The double-mutant mal3D rps1801D also exhibits longer microtubules than mal3D single mutant alone. Our study suggests a possible involvement of mtr1p and the ribosome complex in modulating microtubule dynamics.