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Updated: Jul 15, 2026

Analyzing and Building Nucleic Acid Structures with 3DNA
Published on: April 26, 2013
Structure and function of DnaA N-terminal domains: specific sites and mechanisms in inter-DnaA interaction and in
Yoshito Abe1, Takaaki Jo, Yusaku Matsuda
1Department of Immunology, Graduate School of Pharmaceutical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan.
Abstract:
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.
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