Phosphosites of the yeast centrosome component Spc110 contribute to mitotic exit

Spc110 is an essential component of the spindle pole body (SPB), the yeast equivalent of the centrosome, that recruits the gamma-tubulin complex to the nuclear side of SPB to form the mitotic spindle. Here we identify two phosphosites (S11 and S36) in old (from maternal origin) Spc110. Yeast expressing non-phosphorylatable Spc110S11AS36A were sensitive to the microtubule depolymerizing drug benomyl. In an undisturbed cell cycle, Spc110S11AS36A cells had normal spindles and cell cycle progression until late anaphase. However, Spc110S11AS36A cells were delayed in late-anaphase and presented elevated levels of Cdc14, a protein phosphatase required for mitotic exit, at the SPBs. Thus, we propose that the S11 and S36 phosphosites of Spc110 regulate Cdc14 localization at the SPBs for timely mitotic exit.