Cold Spring Harbor Laboratory, 1 Bungtown Road, Cold Spring Harbor, NY 11724, USA.
Cold Spring Harbor Laboratory, 1 Bungtown Road, Cold Spring Harbor, NY 11724, USA.
Mol Cell. 2021 May 6;81(9):1951-1969.e6. doi: 10.1016/j.molcel.2021.03.003. Epub 2021 Mar 23.
The initiation of DNA replication involves cell cycle-dependent assembly and disassembly of protein complexes, including the origin recognition complex (ORC) and CDC6 AAA ATPases. We report that multiple short linear protein motifs (SLiMs) within intrinsically disordered regions (IDRs) in ORC1 and CDC6 mediate cyclin-CDK-dependent and independent protein-protein interactions, conditional on the cell cycle phase. A domain within the ORC1 IDR is required for interaction between the ORC1 and CDC6 AAA domains in G1, whereas the same domain prevents CDC6-ORC1 interaction during mitosis. Then, during late G1, this domain facilitates ORC1 destruction by a SKP2-cyclin A-CDK2-dependent mechanism. During G1, the CDC6 Cy motif cooperates with cyclin E-CDK2 to promote ORC1-CDC6 interactions. The CDC6 IDR regulates self-interaction by ORC1, thereby controlling ORC1 protein levels. Protein phosphatase 1 binds directly to a SLiM in the ORC1 IDR, causing ORC1 de-phosphorylation upon mitotic exit, increasing ORC1 protein, and promoting pre-RC assembly.
DNA 复制的起始涉及细胞周期依赖性的蛋白质复合物的组装和拆卸，包括起始识别复合物（ORC）和 CDC6AAAATP 酶。我们报告说，ORC1 和 CDC6 中的多个固有无序区域（IDR）内的短线性蛋白质基序（SLiM），在细胞周期阶段的条件下，介导细胞周期蛋白依赖性和非依赖性的蛋白质-蛋白质相互作用。ORC1 IDR 内的一个结构域是在 G1 期 ORC1 和 CDC6AAA 结构域之间相互作用所必需的，而同一结构域在有丝分裂期间阻止 CDC6-ORC1 相互作用。然后，在晚期 G1 期，该结构域通过 SKP2-细胞周期蛋白 A-CDK2 依赖性机制促进 ORC1 的破坏。在 G1 期，CDC6Cy 基序与细胞周期蛋白 E-CDK2 合作，促进 ORC1-CDC6 相互作用。CDC6IDR 通过 ORC1 自我相互作用进行调节，从而控制 ORC1 蛋白水平。蛋白磷酸酶 1 直接结合到 ORC1 IDR 中的 SLiM，在有丝分裂退出时导致 ORC1 去磷酸化，增加 ORC1 蛋白，并促进预复制复合体的组装。
