裂殖酵母Scm3：着丝粒下染色质完整性所需的一种CENP-A受体。
Fission yeast Scm3: A CENP-A receptor required for integrity of subkinetochore chromatin.
作者信息
Pidoux Alison L, Choi Eun Shik, Abbott Johanna K R, Liu Xingkun, Kagansky Alexander, Castillo Araceli G, Hamilton Georgina L, Richardson William, Rappsilber Juri, He Xiangwei, Allshire Robin C
机构信息
Wellcome Trust Centre for Cell Biology and Institute of Cell Biology, School of Biological Sciences, The University of Edinburgh, 6.34 Swann Building, Edinburgh EH93JR, Scotland, UK.
出版信息
Mol Cell. 2009 Feb 13;33(3):299-311. doi: 10.1016/j.molcel.2009.01.019.
The mechanisms ensuring specific incorporation of CENP-A at centromeres are poorly understood. Mis16 and Mis18 are required for CENP-A localization at centromeres and form a complex that is conserved from fission yeast to human. Fission yeast sim1 mutants that alleviate kinetochore domain silencing are defective in Scm3(Sp), the ortholog of budding yeast Scm3(Sc). Scm3(Sp) depends on Mis16/18 for its centromere localization and like them is recruited to centromeres in late anaphase. Importantly, Scm3(Sp) coaffinity purifies with CENP-A(Cnp1) and associates with CENP-A(Cnp1) in vitro, yet localizes independently of intact CENP-A(Cnp1) chromatin and is differentially released from chromatin. While Scm3(Sc) has been proposed to form a unique hexameric nucleosome with CENP-A(Cse4) and histone H4 at budding yeast point centromeres, we favor a model in which Scm3(Sp) acts as a CENP-A(Cnp1) receptor/assembly factor, cooperating with Mis16 and Mis18 to receive CENP-A(Cnp1) from the Sim3 escort and mediate assembly of CENP-A(Cnp1) into subkinetochore chromatin.
确保着丝粒特异性掺入CENP-A的机制目前还知之甚少。Mis16和Mis18是CENP-A在着丝粒定位所必需的，它们形成一个从裂殖酵母到人类都保守的复合物。缓解动粒结构域沉默的裂殖酵母sim1突变体在芽殖酵母Scm3(Sc)的直系同源物Scm3(Sp)中存在缺陷。Scm3(Sp)的着丝粒定位依赖于Mis16/18，并且与它们一样在后期被招募到着丝粒。重要的是，Scm3(Sp)与CENP-A(Cnp1)共亲和纯化，并在体外与CENP-A(Cnp1)结合，但它独立于完整的CENP-A(Cnp1)染色质定位，并且从染色质中差异释放。虽然有人提出Scm3(Sc)在芽殖酵母点着丝粒处与CENP-A(Cse4)和组蛋白H4形成独特的六聚体核小体，但我们更倾向于这样一种模型，即Scm3(Sp)作为CENP-A(Cnp1)受体/组装因子，与Mis16和Mis18合作，从Sim3护送蛋白接收CENP-A(Cnp1)，并介导CENP-A(Cnp1)组装到亚动粒染色质中。
Zotero 插件