Jwa Miri, Kim Jae-hyun, Chan Clarence S M
Institute for Cellular and Molecular Biology, The University of Texas, Austin, TX 78712, USA.
J Cell Biol. 2008 Sep 22;182(6):1099-111. doi: 10.1083/jcb.200802085. Epub 2008 Sep 15.
The Sli15-Ipl1-Bir1 chromosomal passenger complex is essential for proper kinetochore-microtubule attachment and spindle stability in the budding yeast Saccharomyces cerevisiae. During early anaphase, release of the Cdc14 protein phosphatase from the nucleolus leads to the dephosphorylation of Sli15 and redistribution of this complex from kinetochores to the spindle. We show here that the predominantly nucleolar ribosome biogenesis protein Utp7 is also present at kinetochores and is required for normal organization of kinetochore proteins and proper chromosome segregation. Utp7 associates with and regulates the localization of Sli15 and Cdc14. Before anaphase onset, it prevents the premature nucleolar release of Cdc14 and the premature concentration of Sli15 on the spindle. Furthermore, Utp7 can regulate the localization and phosphorylation status of Sli15 independent of its effect on Cdc14 function. Thus, Utp7 is a multifunctional protein that plays essential roles in the vital cellular processes of ribosome biogenesis, chromosome segregation, and cell cycle control.
Sli15-Ipl1-Bir1染色体乘客复合体对于芽殖酵母酿酒酵母中正确的动粒-微管附着和纺锤体稳定性至关重要。在后期早期，Cdc14蛋白磷酸酶从核仁释放导致Sli15去磷酸化，并使该复合体从动粒重新分布到纺锤体。我们在此表明，主要定位于核仁的核糖体生物合成蛋白Utp7也存在于动粒处，是动粒蛋白正常组织和正确染色体分离所必需的。Utp7与Sli15和Cdc14结合并调节其定位。在后期开始之前，它可防止Cdc14过早从核仁释放以及Sli15过早集中在纺锤体上。此外，Utp7可独立于其对Cdc14功能的影响来调节Sli15的定位和磷酸化状态。因此，Utp7是一种多功能蛋白，在核糖体生物合成、染色体分离和细胞周期控制等重要细胞过程中发挥着关键作用。
