RNA primer–primase complexes serve as the signal for polymerase recycling and Okazaki fragment initiation in T4 phage DNA replication
| Autor: | Stephen J. Benkovic, Swathi Gannavaram, Michelle M. Spiering, Philip Hanoian |
|---|---|
| Rok vydání: | 2017 |
| Předmět: |
DNA Replication
0301 basic medicine DNA Single-Stranded DNA-Directed DNA Polymerase 03 medical and health sciences Multienzyme Complexes Escherichia coli Bacteriophage T4 DNA Primers Multidisciplinary DNA clamp Okazaki fragments biology DNA replication DNA Biological Sciences Molecular biology Cell biology 030104 developmental biology Prokaryotic DNA replication DNA Viral biology.protein Replisome Primase DNA polymerase I Primer (molecular biology) |
| Zdroj: | Proceedings of the National Academy of Sciences. 114:5635-5640 |
| ISSN: | 1091-6490 0027-8424 |
| DOI: | 10.1073/pnas.1620459114 |
| Popis: | The opposite strand polarity of duplex DNA necessitates that the leading strand is replicated continuously whereas the lagging strand is replicated in discrete segments known as Okazaki fragments. The lagging-strand polymerase sometimes recycles to begin the synthesis of a new Okazaki fragment before finishing the previous fragment, creating a gap between the Okazaki fragments. The mechanism and signal that initiate this behavior-that is, the signaling mechanism-have not been definitively identified. We examined the role of RNA primer-primase complexes left on the lagging ssDNA from primer synthesis in initiating early lagging-strand polymerase recycling. We show for the T4 bacteriophage DNA replication system that primer-primase complexes have a residence time similar to the timescale of Okazaki fragment synthesis and the ability to block a holoenzyme synthesizing DNA and stimulate the dissociation of the holoenzyme to trigger polymerase recycling. The collision with primer-primase complexes triggering the early termination of Okazaki fragment synthesis has distinct advantages over those previously proposed because this signal requires no transmission to the lagging-strand polymerase through protein or DNA interactions, the mechanism for rapid dissociation of the holoenzyme is always collision, and no unique characteristics need to be assigned to either identical polymerase in the replisome. We have modeled repeated cycles of Okazaki fragment initiation using a collision with a completed Okazaki fragment or primer-primase complexes as the recycling mechanism. The results reproduce experimental data, providing insights into events related to Okazaki fragment initiation and the overall functioning of DNA replisomes. |
| Databáze: | OpenAIRE |
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