Dynamics of DNA replication initiation complex in fission yeast during cell cycle

origin recognition complex （ORC） has been identified as a protein complex of six subunits which binds to an replication origin in in S. Cerevisiae。ORC的作用被认为是复制因素的着陆板。一项附属研究建议ORC在多个过程中的影响超过DNA复制的其他过程，包括沉默、检查点控制和线粒体。不管怎么说，这是不明白的，什么更广泛的ORC是在这些过程的规定下发生的。我们在S中使用了ORC的第五个子单元。pombe、Orp5 （ORC related protein 5）。Orp 5 D1+ D1基因是细胞活性的基本要素，并在不完整的S阶段和进入核扩散的能力中发现了缺陷。对Orp 5温度敏感突变体的三个不同的警告的进一步分析，使Orp 5具有可分离的多个功能：DNA复制、S/M-检查点、S-相位进程、S-相位检查点和相位相位变化的启动。Orp 5-H19突变体是DNA复制启动和检查点控制中的缺陷，S阶段之前的子宫内膜异位症是完整的。另一个突变体，orp 5-K37似乎退出G1阶段，但S阶段已经停止。orp 5-H37在DNA合成本身是完整的，因为M阶段引入了缺陷。在补充中，orp 5-H37在S阶段是DNA损伤检查点的缺陷，该检查点由rad 3-cds 1途径进行。结合在一起，我们认为ORC是一个染色质成分，它是这些事件和管理细胞的基础，以进行细胞周期的性质。

The origin recognition complex (ORC) has been identified as a protein complex of six subunits which binds to an replication origin in S. cerevisiae. The role of ORC is considered as a landing pad for replication factors. The subsequent studies suggest the involvement of ORC in several processes other than DNA replication including silencing, checkpoint control, and mitosis. However, it had been unclear to what extent ORC is involved in the regulation of these processes. We characterized a fifth subunit of ORC in S. pombe, Orp5 (ORC related protein 5). The orp5ィイD1+ィエD1 gene was essential for cell viability, and its depletion resulted in incomplete S-phase and inability to enter mitosis. Further analysis of three different alleles of orp5 temperature sensitive mutants elucidated the multiple functions of Orp5 which were separable : the initiation of DNA replication, S/M-checkpoint, S-phase progression, S-phase checkpoint, and mitosis. The orp5-H19 mutant was defective in DNA replication initiation and checkpoint control which prevent mitosis until S-phase is complete. The other mutant, orp5-K37 appeared to exit G1-phase, but the S-phase was stalled. The orp5-H37 has a deficiency entering M-phase while DNA synthesis itself is complete. In addition, the orp5-H37 was defective in DNA-damage checkpoint in S-phase which are regulated by rad3-cds1 pathway. Taken together, we propose that ORC is a chromatin component which constitutes a base for these events and manage cells to proceed the cell cycle properly.