DNA tridimensional context affects the reactivity of eukaryotic DNA topoisomerase I.
Cleavage sites of eukaryotic DNA topoisomerase I on curved linear DNAs are clustered, map on the same side of the curve (the external one) and their distribution has the same period as the helical repeat, as observed on curved DNA tracts of Crithidia fasciculata, of Saccharomyces cerevisiae ARS1, of pT7CAT and on synthetic DNAs. The effects of the tridimensional context on both the cleavage and the topoisomerization reactions of DNA topoisomerase I were determined using serial DNA constructs made with inserts in which synthetic curves lie in a plane and in which the orientation of the planes of curvature is shifted by 72 degrees, 144 degrees, 216 degrees, 288 degrees and 360 degrees. The insertion of a curve markedly changes the reaction properties of the surrounding sequences.
Dipartimento di Genetica e Biologia Molecolare, Università di Roma La Sapienza, Italy.
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Perini
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Caserta
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Di Mauro
D000818:Animals; D001483:Base Sequence; D003421:Crithidia / Q000235:genetics; D004264:DNA Topoisomerases, Type I / Q000378:metabolism*; D004271:DNA, Fungal / Q000737:chemistry / Q000378:metabolism*; D016054:DNA, Protozoan / Q000737:chemistry / Q000378:metabolism*; D008969:Molecular Sequence Data; D009690:Nucleic Acid Conformation; D012441:Saccharomyces cerevisiae / Q000235:genetics
D004271:DNA, Fungal; D016054:DNA, Protozoan; D004264:DNA Topoisomerases, Type I