Structure and function of DnaA N-terminal domains: specific sites and mechanisms in inter-DnaA interaction and in DnaB helicase loading on oriC

J Biol Chem. 2007 Jun 15;282(24):17816-27. doi: 10.1074/jbc.M701841200. Epub 2007 Apr 9.


DnaA forms a homomultimeric complex with the origin of chromosomal replication (oriC) to unwind duplex DNA. The interaction of the DnaA N terminus with the DnaB helicase is crucial for the loading of DnaB onto the unwound region. Here, we determined the DnaA N terminus structure using NMR. This region (residues 1-108) consists of a rigid region (domain I) and a flexible region (domain II). Domain I has an alpha-alpha-beta-beta-alpha-beta motif, similar to that of the K homology (KH) domain, and has weak affinity for oriC single-stranded DNA, consistent with KH domain function. A hydrophobic surface carrying Trp-6 most likely forms the interface for domain I dimerization. Glu-21 is located on the opposite surface of domain I from the Trp-6 site and is crucial for DnaB helicase loading. These findings suggest a model for DnaA homomultimer formation and DnaB helicase loading on oriC.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Bacterial Proteins / chemistry*
  • Bacterial Proteins / genetics
  • Bacterial Proteins / metabolism*
  • Binding Sites
  • DNA / chemistry
  • DNA / metabolism
  • DNA Replication
  • DNA-Binding Proteins / chemistry*
  • DNA-Binding Proteins / genetics
  • DNA-Binding Proteins / metabolism*
  • DnaB Helicases / chemistry
  • DnaB Helicases / genetics
  • DnaB Helicases / metabolism*
  • Escherichia coli / genetics
  • Escherichia coli / metabolism
  • Escherichia coli Proteins / chemistry*
  • Escherichia coli Proteins / genetics
  • Escherichia coli Proteins / metabolism*
  • Models, Molecular
  • Molecular Sequence Data
  • Origin Recognition Complex*
  • Protein Structure, Quaternary*
  • Protein Structure, Tertiary


  • Bacterial Proteins
  • DNA-Binding Proteins
  • DnaA protein, Bacteria
  • Escherichia coli Proteins
  • OriC chromosomal replication origin
  • Origin Recognition Complex
  • DNA
  • dnaB protein, E coli
  • DnaB Helicases

Associated data

  • PDB/2E0G