Aurora kinase Ipl1 facilitates bilobed distribution of clustered kinetochores to ensure error-free chromosome segregation in Candida albicans

Abstract

Candida albicans, an ascomycete, has an ability to switch to diverse morphological forms. While C. albicans is predominatly diploid, it can tolerate aneuploidy as a survival strategy under stress. Aurora kinase B homolog Ipl1 is a critical ploidy regulator that controls microtubule dynamics and chromosome segregation in Saccharomyces cerevisiae. In this study, we show that Ipl1 in C. albicans has a longer activation loop than that of the well-studied ascomycete S. cerevisiae. Ipl1 localizes to the kinetochores during the G1/S phase and associates with the spindle during mitosis. Ipl1 regulates cell morphogenesis and is required for cell viability. Ipl1 monitors microtubule dynamics which is mediated by separation of spindle pole bodies. While Ipl1 is dispensable for maintaining structural integrity and clustering of kinetochores in C. albicans, it is required for the maintenance of kinetochore geometry to form bilobed structures along the mitotic spindle, a feature of Ipl1 that was not observed in other yeasts. Depletion of Ipl1 results in erroneous kinetochore-microtubule attachments leading to aneuploidy-associated resistance to fluconazole, the most common anti-fungal drug used to treat Candida infections. Taking together, we suggest that Ipl1 spatiotemporally ensures kinetochore geometry to facilitate bipolar spindle assembly crucial for ploidy maintenance in C. albicans.