title: Structure and function of DnaA N-terminal domains: specific sites and mechanisms in inter-DnaA interaction and in DnaB helicase loading on oriC.
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.
authors.affiliation: Department of Immunology, Graduate School of Pharmaceutical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan.
authors.forename: Yoshito
authors.initials: Y
authors.lastname: Abe
authors.forename: Takaaki
authors.initials: T
authors.lastname: Jo
authors.forename: Yusaku
authors.initials: Y
authors.lastname: Matsuda
authors.forename: Chika
authors.initials: C
authors.lastname: Matsunaga
authors.forename: Tsutomu
authors.initials: T
authors.lastname: Katayama
authors.forename: Tadashi
authors.initials: T
authors.lastname: Ueda
mesh_terms: D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D001665:Binding Sites; D004247:DNA / Q000737:chemistry / Q000378:metabolism; D004261:DNA Replication; D004268:DNA-Binding Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D053488:DnaB Helicases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D029968:Escherichia coli Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D008958:Models, Molecular; D008969:Molecular Sequence Data; D051738:Origin Recognition Complex; D020836:Protein Structure, Quaternary; D017434:Protein Structure, Tertiary
chemical_list: D001426:Bacterial Proteins; D004268:DNA-Binding Proteins; C066312:DnaA protein, Bacteria; D029968:Escherichia coli Proteins; C114650:OriC chromosomal replication origin; D051738:Origin Recognition Complex; D004247:DNA; C506730:dnaB protein, E coli; D053488:DnaB Helicases