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

细胞周期中裂殖酵母 DNA 复制起始复合物的动态

• 批准号: 10480193
• 负责人: MURAKAMI Yota
• 金额: $ 2.37万
• 依托单位: KYOTO UNIVERSITY
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (B)
• 财政年份: 1998
• 资助国家: 日本
• 起止时间: 1998 至 1999
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-10480193/
• 关键词: Fission yeast; chromosomal Replication; ORC; Cell cycle; check point control; 複製開始

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.

原点识别复合物（ORC）已被鉴定为六个亚基的蛋白质复合物，与酿酒酵母中的复制起源结合。兽人的作用被认为是复制因素的降落垫。随后的研究表明，除了DNA复制（包括沉默，检查点控制和有丝分裂）以外，ORC参与了几个过程。但是，目前尚不清楚ORC在这些过程的调节中涉及多大程度。我们表征了S. pombe，ORP5（ORC相关蛋白5）中的第五个亚基。 ORP5II D1+IE D1基因对于细胞活力是必不可少的，其定义导致S期不完整，无法进入有丝分裂。对ORP5温度敏感突变体的三个不同等位基因的进一步分析阐明了ORP5的多个功能，这些功能是分开的：DNA复制，S/M-CHECKPOINT，S阶段，S期进展，S期检查点和有丝分裂的主动性。 ORP5-H19突变体在DNA复制计划和检查点控制中有缺陷，该计划可防止有丝分裂，直到S相完成。另一个突变体ORP5-K37似乎退出了G1期，但S期停滞了。 ORP5-H37具有进入M期的缺陷，而DNA合成本身已完成。另外，ORP5-H37在S期的DNA损伤检查点中有缺陷，该检查点受RAD3-CDS1途径调节。综上所述，我们建议兽人是一种染色质成分，它构成了这些事件的基础，并管理细胞正确进行细胞周期。