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Rfc5, a small subunit of replication factor C complex, couples DNA replication and mitosis in budding yeast
K Sugimoto1, T Shimomura, K Hashimoto
1Department of Molecular Biology, Faculty of Science, Nagoya University, Japan.
Summary
Replication Factor C (RFC) subunit 5 (rfc5) mutations impair DNA replication and the S phase checkpoint in yeast. RFC may directly sense DNA replication status and signal to the cell cycle checkpoint.
Area of Science:
- Cell cycle regulation
- DNA replication
- Molecular genetics
Background:
- The S phase checkpoint prevents mitotic entry during DNA replication inhibition.
- Spk1/Mec2/Rad53/Sad1 is a key protein kinase coupling S phase to mitosis in Saccharomyces cerevisiae.
Purpose of the Study:
- Identify genes interacting with Spk1.
- Investigate the role of RFC5 in DNA replication and checkpoint control.
Main Methods:
- Isolated temperature-sensitive rfc5-1 mutation in yeast.
- Assessed genetic interactions with SPK1.
- Analyzed cell viability and chromosome segregation.
- Studied effects of POL30 overexpression.
Main Results:
- rfc5-1 mutation caused mitotic entry defects and loss of viability.
- SPK1 overexpression suppressed rfc5-1.
- POL30 overexpression suppressed replication defects but not checkpoint defects.
- rfc5 mutation impairs both DNA replication and the S phase checkpoint.
Conclusions:
- RFC5 is essential for DNA replication and S phase checkpoint function.
- Replication Factor C likely plays a direct role in sensing DNA replication status.
- RFC transmits signals to the checkpoint machinery for cell cycle control.