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.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Amino Acid Sequence
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Bacterial Proteins / chemistry*
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Bacterial Proteins / genetics
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Bacterial Proteins / metabolism*
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Binding Sites
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DNA / chemistry
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DNA / metabolism
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DNA Replication
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DNA-Binding Proteins / chemistry*
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DNA-Binding Proteins / genetics
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DNA-Binding Proteins / metabolism*
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DnaB Helicases / chemistry
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DnaB Helicases / genetics
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DnaB Helicases / metabolism*
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Escherichia coli / genetics
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Escherichia coli / metabolism
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Escherichia coli Proteins / chemistry*
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Escherichia coli Proteins / genetics
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Escherichia coli Proteins / metabolism*
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Models, Molecular
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Molecular Sequence Data
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Origin Recognition Complex*
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Protein Structure, Quaternary*
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Protein Structure, Tertiary
Substances
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Bacterial Proteins
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DNA-Binding Proteins
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DnaA protein, Bacteria
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Escherichia coli Proteins
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OriC chromosomal replication origin
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Origin Recognition Complex
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DNA
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dnaB protein, E coli
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DnaB Helicases