The clamp-loader-helicase interaction in Bacillus. Atomic force microscopy reveals the structural organisation of the DnaB-tau complex in Bacillus

J Mol Biol. 2004 Feb 13;336(2):381-93. doi: 10.1016/j.jmb.2003.12.043.

Abstract

The clamp-loader-helicase interaction is an important feature of the replisome. Although significant biochemical and structural work has been carried out on the clamp-loader-clamp-DNA polymerase alpha interactions in Escherichia coli, the clamp-loader-helicase interaction is poorly understood by comparison. The tau subunit of the clamp-loader mediates the interaction with DnaB. We have recently characterised this interaction in the Bacillus system and established a tau(5)-DnaB(6) stoichiometry. Here, we have obtained atomic force microscopy images of the tau-DnaB complex that reveal the first structural insight into its architecture. We show that despite the reported absence of the shorter gamma version in Bacillus, tau has a domain organisation similar to its E.coli counterpart and possesses an equivalent C-terminal domain that interacts with DnaB. The interaction interface of DnaB is also localised in its C-terminal domain. The combined data contribute towards our understanding of the bacterial replisome.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adenosine Triphosphatases / chemistry
  • Adenosine Triphosphatases / metabolism
  • Adenosine Triphosphatases / ultrastructure
  • Bacillus subtilis / enzymology*
  • Bacillus subtilis / genetics
  • Bacterial Proteins*
  • Base Sequence
  • DNA Helicases / antagonists & inhibitors
  • DNA Helicases / chemistry*
  • DNA Helicases / metabolism
  • DNA Helicases / ultrastructure*
  • DNA Replication
  • DnaB Helicases
  • Electron Spin Resonance Spectroscopy
  • Microscopy, Atomic Force*
  • Models, Molecular
  • Molecular Sequence Data
  • Protein Binding
  • Protein Structure, Quaternary
  • Protein Structure, Tertiary
  • Protein Subunits / chemistry
  • Protein Subunits / metabolism*

Substances

  • Bacterial Proteins
  • Protein Subunits
  • Adenosine Triphosphatases
  • DNA Helicases
  • DnaB Helicases