Molecular and Computational Biology Program, University of Southern California, Los Angeles, California 90089-2910, USA.
J Biol Chem. 2011 Sep 23;286(38):32918-30. doi: 10.1074/jbc.M111.282541. Epub 2011 Aug 3.
The minichromosome maintenance (MCM) complex, a replicative helicase, is a heterohexamer essential for DNA duplication and genome stability. We identified Schizosaccharomyces pombe mcb1(+) (Mcm-binding protein 1), an apparent orthologue of the human MCM-binding protein that associates with a subset of MCM complex proteins. mcb1(+) is an essential gene. Deletion of mcb1(+) caused cell cycle arrest after several generations with a cdc phenotype and disrupted nuclear structure. Mcb1 is an abundant protein, constitutively present across the cell cycle. It is widely distributed in cytoplasm and nucleoplasm and bound to chromatin. Co-immunoprecipitation suggested that Mcb1 interacts robustly with Mcm3-7 but not Mcm2. Overproduction of Mcb1 disrupted the association of Mcm2 with other MCM proteins, resulting in inhibition of DNA replication, DNA damage, and activation of the checkpoint kinase Chk1. Thus, Mcb1 appears to antagonize the function of MCM helicase.
微小染色体维持 (MCM) 复合物是一种复制解旋酶，是 DNA 复制和基因组稳定性所必需的异六聚体。我们鉴定了裂殖酵母 mcb1(+)（Mcm 结合蛋白 1），它是与人 MCM 结合蛋白的明显同源物，与 MCM 复合物蛋白的亚基结合。mcb1(+) 是一个必需基因。mcb1(+)缺失后，细胞周期在经历几代后停滞，表现出 cdc 表型并破坏核结构。Mcb1 是一种丰富的蛋白质，在整个细胞周期中持续存在。它广泛分布于细胞质和核质中，并与染色质结合。共免疫沉淀表明 Mcb1 与 Mcm3-7 强烈相互作用，但不与 Mcm2 相互作用。Mcb1 的过表达破坏了 Mcm2 与其他 MCM 蛋白的结合，导致 DNA 复制抑制、DNA 损伤和检查点激酶 Chk1 的激活。因此，Mcb1 似乎拮抗 MCM 解旋酶的功能。
