Spindle pole body-associated Atg11, an autophagy-related protein, regulates microtubule dynamics essential for high-fidelity chromosome segregation

Emerging studies hint at the roles of autophagy-related proteins in various cellular processes in a eukaryotic cell. To understand if autophagy-related proteins influence genome stability, we examined a cohort of 35 autophagy mutants in Saccharomyces cerevisiae. We observed cells lacking Atg11 show poor mitotic stability of minichromosomes. Atg11 molecules dynamically localize to the spindle pole bodies (SPBs). Loss of Atg11 leads to a delayed cell cycle progression. Such cells accumulate at metaphase at an elevated temperature that is relieved when the spindle assembly checkpoint is inactivated. Indeed, atg11 Δ cells have stabilized securin levels, that prevent anaphase onset, confirming chromosome biorientation defects associated with the mutant. Atg11 functions in the Kar9-dependent spindle positioning pathway and maintains Kar9 asymmetry by facilitating proper dynamic instability of astral microtubules (aMTs). Taken together, this study uncovers a non-canonical role of Atg11 in facilitating MT dynamics crucial for chromosome segregation.