Regulating the yeast kinetochore by ubiquitin-dependent degradation and skp1p-mediated phosphorylation
Regulating the yeast kinetochore by ubiquitin-dependent degradation and skp1p-mediated phosphorylation
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DOI：
10.1016/s0092-8674(00)80435-3
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发表时间：
1997-11-14
期刊：
影响因子：
64.5
通讯作者：
Sorger, PK
中科院分区：
文献类型：
--
作者：
Kaplan, KB;Hyman, AA;Sorger, PK
在酿酒酵母中，四蛋白Cbf3复合体与着丝粒DNA的基本CDEIII区域结合，启动动粒组装。我们报道了重组蛋白Cbf3p的重组及其p58(Ctf13)和p23(Skp1)亚基的分析。P23(Skp1)在酵母中同时具有G1和G2的特异性功能，并与p58(Ctf13)和泛素结合复合体Scu1(CDC4)的基本CDC4p组分结合。我们证明了p23(Skp1)在Cbf3p中的功能是通过磷酸化激活p58(Ctf13)。P58(Ctf13)是一种针对蛋白小体的不稳定蛋白，可能通过Scul(Cdc4)介导的泛素化。因此，p58似乎在p23(Skp1)依赖的步骤中被磷酸化激活，并在泛素依赖的步骤中被蛋白小体降解。我们认为，在S阶段，Cbf3p的组装与着丝粒的复制存在耦合的激活和破坏。
In S. cerevisiae, the four-protein Cbf3 complex binds to the essential CDEIII region of centromeric DNA to initiate kinetochore assembly. We report the reconstitution of Cbf3p from recombinant proteins and an analysis of its p58(Ctf13) and p23(Skp1) subunits. p23(Skp1) has both G1- and G2-specific functions in yeast and binds to p58(Ctf13) and to the essential Cdc4p component of the ubiquitin conjugating complex Scul(Cdc4). We show that the function of p23(Skp1) in Cbf3p is to activate p58(Ctf13) by phosphorylation. p58(Ctf13) is an unstable protein that is targeted to the proteosome, probably by Scul(Cdc4)-mediated ubiquitination. Thus, p58 appears to be activated by phosphorylation in a p23(Skp1)-dependent step and degraded by the proteosome in a ubiquitin-dependent step. We propose that coupled activation and destruction link the assembly of Cbf3p to the duplication of centromeres in S phase.