Resolution of Holliday junctions by RuvC resolvase: cleavage specificity and DNA distortion.
E. coli RuvC protein resolves Holliday junctions during genetic recombination and postreplication repair. Using small synthetic junctions, we show that junction recognition is structure-specific and occurs in the absence of metal cofactors. In the presence of Mg2+, Holliday junctions are resolved by the introduction of symmetrically related nicks at the 3' side of thymine residues. The nicked duplex products are repaired by the action of DNA ligase. Within the RuvC-Holliday junction complex, the DNA is distorted such that 2 of the 4 strands become hypersensitive to hydroxyl radical attack. The ionic requirements of binding, hydroxyl radical sensitivity, and strand cleavage indicate three distinct steps in the mechanism of RuvC-mediated Holliday junction resolution: structure-specific recognition, DNA distortion, and sequence-dependent cleavage.
Bennett
R J
RJ
Imperial Cancer Research Fund, South Mimms, Hertfordshire, England.
Dunderdale
H J
HJ
West
S C
SC
D001426:Bacterial Proteins / Q000378:metabolism*; D001483:Base Sequence; D001665:Binding Sites; D004247:DNA / Q000378:metabolism*; D011088:DNA Ligases / Q000378:metabolism; D004269:DNA, Bacterial / Q000378:metabolism*; D003850:Deoxyribonuclease I; D004706:Endodeoxyribonucleases; D004926:Escherichia coli / Q000378:metabolism*; D029968:Escherichia coli Proteins; D005609:Free Radicals; D017665:Hydroxyl Radical; D008969:Molecular Sequence Data; D009838:Oligodeoxyribonucleotides / Q000138:chemical synthesis / Q000378:metabolism*
D001426:Bacterial Proteins; D004269:DNA, Bacterial; D029968:Escherichia coli Proteins; D005609:Free Radicals; D009838:Oligodeoxyribonucleotides; C069806:ruvC protein, E coli; D017665:Hydroxyl Radical; D004247:DNA; D004706:Endodeoxyribonucleases; D003850:Deoxyribonuclease I; D011088:DNA Ligases