Specificity of binding to four-way junctions in DNA by bacteriophage T7 endonuclease I.
T7 endonuclease I binds specifically to four-way junctions in duplex DNA and promotes their resolution into linear duplexes. Under conditions in which the nuclease activity is blocked by the absence of divalent cations, the enzyme forms a distinct protein-DNA complex with the junction, as detected by gel retardation and filter binding assays. The formation of this complex is structure-specific and contrasts with the short-lived binding complexes formed on linear duplex DNA. The binding complex between T7 endonuclease I and a synthetic Holliday junction analog has been probed with hydroxyl radicals. The results indicate that the nuclease binds all four strands about the junction point.
Parsons
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Imperial Cancer Research Fund, Clare Hall Laboratories, South Mimms, Herts, UK.
West
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D001483:Base Sequence; D001667:Binding, Competitive; D004247:DNA / Q000378:metabolism*; D003850:Deoxyribonuclease I / Q000378:metabolism*; D006878:Hydroxides; D017665:Hydroxyl Radical; D008969:Molecular Sequence Data; D009690:Nucleic Acid Conformation; D011189:Potassium Chloride / Q000494:pharmacology; D013379:Substrate Specificity; D013604:T-Phages / Q000201:enzymology*
D006878:Hydroxides; D017665:Hydroxyl Radical; D011189:Potassium Chloride; D004247:DNA; D003850:Deoxyribonuclease I