PMID:16354656
| Citation |
Tanaka, T and Masai, H (2006) Stabilization of a stalled replication fork by concerted actions of two helicases. J. Biol. Chem. 281:3484-93 |
|---|---|
| Abstract |
PriA helicase plays crucial roles in restoration of arrested replication forks. It carries a "3' terminus binding pocket" in its N-terminal DNA binding domain, which is required for high affinity binding of PriA to a fork carrying a 3'-end of a nascent leading strand at the branch. We show that the abrogation of the 3' terminus recognition either by a mutation in the 3' terminus binding pocket or by the bulky modification of the 3'-end leads to unwinding of the unreplicated duplex arm on this fork, causing potential fork destabilization. This indicates a critical role of the 3' terminus binding pocket of PriA in its "stable" binding at the fork for primosome assembly. In contrast, PriA unwinds the unreplicated duplex region on a fork without a 3'-end, potentially destabilizing the fork. However, this process is inhibited by RecG helicase, capable of regressing the fork until the 3'-end of the nascent leading strand reaches the branch. PriA now stably binds to this regressed fork, stabilizing it. Using a model arrest-fork-substrate, we reconstitute the above process in vitro with RecG and PriA proteins. Our results present a novel mechanism by which two helicases function in a highly coordinated manner to generate a structure in which an arrested fork is stabilized for further repair and/or replication restart. |
| Links |
PubMed Online version:10.1074/jbc.M510979200 |
| Keywords |
Adenosine Triphosphatases/chemistry; Adenosine Triphosphatases/physiology; Adenosine Triphosphate/chemistry; Bacterial Proteins/chemistry; DNA/chemistry; DNA Helicases/chemistry; DNA Helicases/physiology; DNA Repair; Deoxyribonuclease I/metabolism; Deoxyribonucleases/metabolism; Electrophoresis, Polyacrylamide Gel; Escherichia coli Proteins/chemistry; Escherichia coli Proteins/physiology; Models, Chemical; Models, Genetic; Mutation; Oligonucleotides/chemistry; Protein Binding; Protein Structure, Tertiary; Substrate Specificity |
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