Mammalian Mcm2/4/6/7 complex forms a toroidal structure
Mammalian Mcm2/4/6/7 complex forms a toroidal structure
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DOI：
10.1046/j.1365-2443.2003.00645.x
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发表时间：
2003-05-01
期刊：
影响因子：
2.1
通讯作者：
Nojima, H
中科院分区：
文献类型：
--
作者：
Yabuta, N;Kajimura, N;Nojima, H
背景：Mcm蛋白是一个由6个同源蛋白（Mcm 2 -7）组成的家族，在DNA复制中起重要作用。结果：人Mcm 2/4/6/7四聚体形成环状结构，中心有一个直径约3-4 nm的空腔，空腔的直径约为10 - 20 nm。使用电子显微镜进行观察，采用单个颗粒的图像分析。最主要的平均图像显示了包含四个凸起形成角的环形，其中一个比其他的大。这种结构非常类似于小鼠Mcm 2/4/6/7四聚体，其独立制备并通过电子显微镜分析。这些环形结构是不同的Mcm 4/6/7六聚体，这也是通过电子显微镜检查。GST（谷胱甘肽S-转移酶）下拉和两个杂交实验表明，一个假定的Mcm 6-Mcm 6铰链有助于形成的Mcm 7/4/6/6/4/7 heterohexamer.Conclusions：Mcm 2/4/6/7四聚体形成一个环形结构，是不同的Mcm 4/6/7六聚体的大小和形状。
Background: The Mcm proteins are a family of six homologous proteins (Mcm2-7) that play an important role in DNA replication. They form Mcm4/6/7 and Mcm2/4/6/7 complexes, but their structures are not known.Results: We found that the human Mcm2/4/6/7 tetramer forms a toroidal structure, with a central cavity about 3-4 nm in diameter. Observations were made using electron microscopy, employing the image analysis of single particles. The most predominant averaged image displayed a toroid harbouring four bulges forming corners, one of which was larger than the others. This structure was very similar to the mouse Mcm2/4/6/7 tetramer that was independently prepared and analysed by electron microscopy. These toroidal structures are distinct from that of the Mcm4/6/7 hexamer, which was also examined by electron microscopy. GST(glutathione S-transferase)-pull down and two hybrid experiments suggest that a putative Mcm6-Mcm6 hinge contributes to the formation of the Mcm7/4/6/6/4/7 heterohexamer.Conclusions: The Mcm2/4/6/7 tetramer forms a toroidal structure that is distinct from that of the Mcm4/6/7 hexamer in size and shape.