Fission yeast Mes1p ensures the onset of meiosis II by blocking degradation of cyclin Cdc13p
Fission yeast Mes1p ensures the onset of meiosis II by blocking degradation of cyclin Cdc13p
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DOI：
10.1038/nature03406
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发表时间：
2005-03-24
期刊：
影响因子：
64.8
通讯作者：
Yamamoto, M
中科院分区：
文献类型：
--
作者：
Izawa, D;Goto, M;Yamamoto, M
减数分裂是真核生物中产生卵子、精子和孢子的一种特殊的核分裂形式。减数分裂由连续发生的第一次（MI）和第二次（MII）减数分裂组成。MI是减数分裂的，来自双亲的同源染色体分离。MI由涉及减数分裂特异性粘着蛋白及其保护蛋白的复杂机制支持（1）。MII是等长的，其中复制的姐妹染色单体像有丝分裂一样分开。MII通常被认为在机制上模拟有丝分裂。然而，分裂酵母Mes 1 p是MII所必需的，而不是有丝分裂。mes 1-B44突变体在MII 2之前停止。mes 1的转录在营养细胞中是低的，并且在晚MI和晚MII 3之间的窄窗口中增强。mes 1 mRNA经历减数分裂特异性剪接（4）。在这里，我们表明，Mes 1 p是一个因素，抑制细胞周期蛋白Cdc 13 p在后期I的降解。Mes 1 p与APC/C（后期促进复合物/环体）的激活剂Slp 1 p结合，并抵消其在蛋白水解中参与Cdc 13 p的功能。抑制APC/C依赖性降解Cdc 13 p的Mes 1 p在非洲爪蟾卵提取物中再现。因此，我们认为Mes 1 p在保存执行MII所需的足够水平的MPF（M期促进因子）活性方面具有关键功能。
Meiosis is a special form of nuclear division to generate eggs, spermand spores in eukaryotes. Meiosis consists of the first (MI) and the second (MII) meiotic divisions, which occur consecutively. MI is reductional, in which homologous chromosomes derived from parents segregate. MI is supported by an elaborate mechanism involving meiosis-specific cohesin and its protector(1). MII is equational, in which replicated sister-chromatids separate as in mitosis. MII is generally considered to mimic mitosis in mechanism. However, fission yeastMes1p is essential for MII but dispensable for mitosis. The mes1-B44 mutant arrests before MII2. Transcription of mes1 is low in vegetative cells and boosted in a narrow window between late MI and late MII3. The mes1 mRNA undergoes meiosis-specific splicing(4). Here we show that Mes1p is a factor that suppresses the degradation of cyclin Cdc13p at anaphase I. Mes1p binds to Slp1p, an activator of APC/C ( anaphase promoting complex/cyclosome), and counteracts its function to engage Cdc13p in proteolysis. Inhibition of APC/C-dependent degradation of Cdc13p by Mes1p was reproduced in a Xenopus egg extract. We therefore propose that Mes1p has a key function in saving a sufficient level of MPF ( M-phase-promoting factor) activity required for the execution of MII.