Abstract
The DNA molecules bound to RecA filaments are extended 1.5-fold relative to B-form DNA. This extended DNA structure may be important in the recognition of homology between single-stranded DNA (ssDNA) and double-stranded DNA (dsDNA). In this study, we show that the K286N mutation specifically impaired the dsDNA unwinding and homologous pairing activities of RecA, without an apparent effect on dsDNA binding itself. In contrast, the R243Q mutation caused defective dsDNA unwinding, due to the defective dsDNA binding of the C-terminal domain of RecA. These results provide new evidence that dsDNA unwinding is essential to homology recognition between ssDNA and dsDNA during homologous pairing.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Amino Acid Substitution / genetics
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DNA / chemistry
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DNA / genetics
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DNA / metabolism*
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DNA, Single-Stranded / chemistry
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DNA, Single-Stranded / genetics
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DNA, Single-Stranded / metabolism
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DNA, Superhelical / chemistry
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DNA, Superhelical / genetics
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DNA, Superhelical / metabolism
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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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Escherichia coli*
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Mutation / genetics*
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Nucleic Acid Conformation
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Peptide Fragments / chemistry
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Peptide Fragments / genetics
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Peptide Fragments / metabolism
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Protein Binding
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Rec A Recombinases / chemistry
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Rec A Recombinases / genetics*
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Rec A Recombinases / metabolism*
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Sequence Deletion / genetics
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Sequence Homology, Nucleic Acid*
Substances
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DNA, Single-Stranded
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DNA, Superhelical
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DNA-Binding Proteins
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Peptide Fragments
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DNA
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Rec A Recombinases