The molecular basis of monopolin recruitment to the kinetochore.
The molecular basis of monopolin recruitment to the kinetochore.
复制标题
单极蛋白募集到着丝粒的分子基础。
DOI：
10.1007/s00412-019-00700-0
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发表时间：
2019
期刊：
影响因子：
1.6
通讯作者：
Marston,AdeleL
中科院分区：
文献类型：
--
作者：
Plowman,Rebecca;Singh,Namit;Tromer,EelcoC;Payan,Angel;Duro,Eris;Spanos,Christos;Rappsilber,Juri;Snel,Berend;Kops,GeertJPL;Corbett,KevinD;Marston,AdeleL
monopolin复合物是一种多功能分子交联剂，其在S.庞贝结合并组织有丝分裂着丝粒，以防止异常着丝粒-微管相互作用。在芽殖酵母中S.酿酒酵母的着丝粒结合单个微管，单节蛋白复合体在减数分裂 I 中交联和单向姐妹着丝粒，从而实现同源物的生物取向和分离。在这里，我们发现单粒子复合体亚基 Csm1 及其在着丝粒蛋白 Dsn1 上的结合位点广泛分布在整个真核生物中，表明在着丝粒组织和功能中具有保守的作用。我们发现芽殖酵母 Csm1 结合 Dsn1 中的两个保守基序，一个（称为 Box 1）代表祖先的、广泛保守的单孢子结合基序，第二个（称为 Box 2-3）可能在增强姐妹动粒交联的特异性方面发挥作用。我们发现 Box 1 和 Box 2-3 结合 Csm1 上相同的保守疏水腔，表明这些基序之间存在竞争或切换。使用基于结构的突变体，我们还发现 Box 1 和 Box 2-3 对于减数分裂中的单孢子功能至关重要。我们在 Box 2-3 中鉴定出两个保守的丝氨酸残基，它们在减数分裂中被磷酸化，并且其突变为天冬氨酸稳定了 Csm1-Dsn1 结合，表明这些残基的受调节磷酸化可能在姐妹着丝粒交联特异性中发挥作用。总的来说，我们的结果揭示了单粒子复合体是真核生物中广泛保守的着丝粒组织者，出芽酵母通过添加第二个可调节的单粒子结合界面来共同选择介导姐妹着丝粒交联。
The monopolin complex is a multifunctional molecular crosslinker, which inS. pombebinds and organises mitotic kinetochores to prevent aberrant kinetochore-microtubule interactions. In the budding yeastS. cerevisiae, whose kinetochores bind a single microtubule, the monopolin complex crosslinks and mono-orients sister kinetochores in meiosis I, enabling the biorientation and segregation of homologs. Here, we show that both the monopolin complex subunit Csm1 and its binding site on the kinetochore protein Dsn1 are broadly distributed throughout eukaryotes, suggesting a conserved role in kinetochore organisation and function. We find that budding yeast Csm1 binds two conserved motifs in Dsn1, one (termed Box 1) representing the ancestral, widely conserved monopolin binding motif and a second (termed Box 2-3) with a likely role in enforcing specificity of sister kinetochore crosslinking. We find that Box 1 and Box 2-3 bind the same conserved hydrophobic cavity on Csm1, suggesting competition or handoff between these motifs. Using structure-based mutants, we also find that both Box 1 and Box 2-3 are critical for monopolin function in meiosis. We identify two conserved serine residues in Box 2-3 that are phosphorylated in meiosis and whose mutation to aspartate stabilises Csm1-Dsn1 binding, suggesting that regulated phosphorylation of these residues may play a role in sister kinetochore crosslinking specificity. Overall, our results reveal the monopolin complex as a broadly conserved kinetochore organiser in eukaryotes, which budding yeast have co-opted to mediate sister kinetochore crosslinking through the addition of a second, regulatable monopolin binding interface.