Modulation of mitomycin cross-linking by DNA bending in the Escherichia coli CAP protein-DNA complex.
We have examined the comparative reactivity of mitomycin cross-linking sites in DNA molecules either free in solution or complexed with Escherichia coli CAP protein. Sites in the region to which the protein is bound show strongly variable cross-linking by the drug. The reactivity of a CpG site located where the minor groove is narrowed by bending toward the protein was decreased by about 4-fold, compared to free DNA. The reactivity of a site placed so that the minor groove is widened by the bend was reduced by about 25%, and the reactivity of a (CpG)3 sequence facing primarily away from the protein was reduced 25-fold by CAP binding. These results support the view that local DNA structure plays a critical role in determining the efficiency of cross-linking.
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Department of Chemistry, Yale University, New Haven, Connecticut 06511.
Crothers
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D001483:Base Sequence; D001665:Binding Sites; D003432:Cross-Linking Reagents; D002373:Cyclic AMP Receptor Protein / Q000378:metabolism*; D004269:DNA, Bacterial / Q000235:genetics / Q000378:metabolism*; D004926:Escherichia coli / Q000378:metabolism*; D008937:Mitomycins / Q000378:metabolism*; D008969:Molecular Sequence Data; D009690:Nucleic Acid Conformation; D011485:Protein Binding
D003432:Cross-Linking Reagents; D002373:Cyclic AMP Receptor Protein; D004269:DNA, Bacterial; D008937:Mitomycins