DnaG interacts with a linker region that joins the N- and C-domains of DnaB and induces the formation of 3-fold symmetric rings

Jenny Thirlway, Ian J. Turner, Christopher T. Gibson, Laurence Gardiner, Kevin Brady, Stephanie Allen, Clive J. Roberts, Panos Soultanas

Research output: Contribution to journalArticlepeer-review

33 Citations (Scopus)

Abstract

Loading of the replicative ring helicase onto the origin of replication (oriC) is the final outcome of a well coordinated series of events that collectively constitute a primosomal cascade. Once the ring helicase is loaded, it recruits the primase and signals the switch to the polymerization mode. The transient nature of the helicase-primase (DnaB-DnaG) interaction in the Escherichia coli system has hindered our efforts to elucidate its structure and function. Taking advantage of the stable DnaB-DnaG complex in Bacillus stearothermophilus, we have reviewed conflicting mutagenic data from other bacterial systems and shown that DnaG interacts with the flexible linker that connects the N- and C-terminal domains of DnaB. Furthermore, atomic force microscopy (AFM) imaging experiments show that binding of the primase to the helicase induces predominantly a 3-fold symmetric morphology to the hexameric ring. Overall, three DnaG molecules appear to interact with the hexameric ring helicase but a small number of complexes with two and even one DnaG molecule bound to DnaB were also detected. The structural/functional significance of these data is discussed and a speculative structural model for this complex is suggested.

Original languageEnglish
Pages (from-to)2977-2986
Number of pages10
JournalNucleic Acids Research
Volume32
Issue number10
DOIs
Publication statusPublished - 15 Jun 2004
Externally publishedYes

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