Coupling DNA unwinding activity with primer synthesis in the bacteriophage T4 primosome
Open Access
- 18 October 2009
- journal article
- research article
- Published by Springer Science and Business Media LLC in Nature Chemical Biology
- Vol. 5 (12), 904-912
- https://doi.org/10.1038/nchembio.236
Abstract
The unwinding and priming activities of the bacteriophage T4 primosome, which consists of a hexameric helicase (gp41) translocating 5′ to 3′ and an oligomeric primase (gp61) synthesizing primers 5′ to 3′, has been investigated on DNA hairpins manipulated by a magnetic trap. We find that the T4 primosome continuously unwinds the DNA duplex while allowing for primer synthesis through a primosome disassembly mechanism or a novel DNA looping mechanism. A fused gp61-gp41 primosome unwinds and primes DNA exclusively via the DNA looping mechanism. Other proteins within the replisome control the partitioning of these two mechanisms disfavoring primosome disassembly thereby increasing primase processivity. In contrast priming in bacteriophage T7 involves discrete pausing of the primosome and in Escherichia coli appears to be associated primarily with dissociation of the primase from the helicase. Thus nature appears to use several strategies to couple the disparate helicase and primase activities within primosomes.Keywords
This publication has 31 references indexed in Scilit:
- RNA Primer Handoff in Bacteriophage T4 DNA ReplicationPublished by Elsevier BV ,2008
- Single-molecule studies of fork dynamics in Escherichia coli DNA replicationNature Structural & Molecular Biology, 2008
- Real-time observation of bacteriophage T4 gp41 helicase reveals an unwinding mechanismProceedings of the National Academy of Sciences of the United States of America, 2007
- The Oligomeric T4 Primase Is the Functional Form duringReplicationPublished by Elsevier BV ,2005
- The utility of a two‐color fluorescence electrophoretic mobility shift assay procedure for the analysis of DNA replication complexesElectrophoresis, 2004
- The primase active site is on the outside of the hexameric bacteriophage T7 gene 4 helicase-primase ringJournal of Molecular Biology, 2001
- Replisome-Mediated DNA ReplicationAnnual Review of Biochemistry, 2001
- Stoichiometry and DNA Unwinding by the Bacteriophage T4 41:59 HelicasePublished by Elsevier BV ,1996
- Accessory proteins function as matchmakers in the assembly of the T4 DNA polymerase holoenzymeCurrent Biology, 1995
- Distribution of growing points in DNA of bacteriophage T4Journal of Molecular Biology, 1968