Coupling DNA unwinding activity with primer synthesis in the bacteriophage T4 primosome

Maria Manosas, Michelle M. Spiering, Zhihao Zhuang, Stephen J. Benkovic, Vincent Croquette

Research output: Contribution to journalArticlepeer-review

78 Scopus citations


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′ have 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 new 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 by disfavoring primosome disassembly, thereby increasing primase processivity. In contrast to T4, priming in bacteriophage T7 and Escherichia coli involves discrete pausing of the primosome and dissociation of the primase from the helicase, respectively. Thus nature appears to use several strategies to couple the disparate helicase and primase activities within primosomes.

Original languageEnglish (US)
Pages (from-to)904-912
Number of pages9
JournalNature Chemical Biology
Issue number12
StatePublished - Dec 2009

All Science Journal Classification (ASJC) codes

  • Molecular Biology
  • Cell Biology


Dive into the research topics of 'Coupling DNA unwinding activity with primer synthesis in the bacteriophage T4 primosome'. Together they form a unique fingerprint.

Cite this