A study of the B-Z transition of the AC-rich region of the repeat unit of a satellite DNA from Cebus by means of chemical probes.
The conformational changes induced by negative supercoiling in the AC-rich region of the repeat unit of a Cebus satellite DNA has been studied by chemical probes sensitive to alterations in DNA conformation. This region is constituted of a (GT/CA)n stretch (15 less than or equal to n less than or equal to 18) associated to a sequence rich in GT/CA. At high superhelical density, at least 100 base pairs in the AC-rich region adopt the Z conformation as judged by diethyl pyrocarbonate reactivity. This is confirmed by diethyl pyrocarbonate footprinting of the complex between antibodies to Z-DNA and the AC-rich region. Osmium tetroxide and hydroxylamine reveal some distortions of the Z double helix in the (GT/CA)n stretch also. The terminal T residues of the stretch are hyperreactive with osmium tetroxide; the terminal left C residues but not the terminal right C residues are hyperreactive with hydroxylamine. Substitution of a few base pairs in the middle of the (GT/CA)n stretch induces also some distortions of the Z double helix. In the GT/CA-rich sequence, distortion of the Z double helix is also supported by the hyperreactivity of osmium tetroxide with several T and C residues.
Vogt
N
N
Centre de Biophysique Moleculaire, Centre National de la Recherche Scientifique, Orleans, France.
Rousseau
N
N
Leng
M
M
Malfoy
B
B
D000818:Animals; D001482:Base Composition; D001483:Base Sequence; D002428:Cebus; D055598:Chemical Phenomena; D002621:Chemistry; D004276:DNA, Satellite; D004047:Diethyl Pyrocarbonate; D019811:Hydroxylamine; D006898:Hydroxylamines; D007118:Immunoassay; D008969:Molecular Sequence Data; D009690:Nucleic Acid Conformation; D009993:Osmium Tetroxide; D012091:Repetitive Sequences, Nucleic Acid; D013463:Sulfuric Acid Esters
D004276:DNA, Satellite; D006898:Hydroxylamines; D013463:Sulfuric Acid Esters; D019811:Hydroxylamine; C007482:dimethyl sulfate; D004047:Diethyl Pyrocarbonate; D009993:Osmium Tetroxide