title: DNA tertiary structures formed in vitro by misaligned hybridization of multiple tandem repeat sequences.
abstract: DNA tertiary structures are shown to be formed by denaturation and reannealing in vitro of molecularly-cloned DNA containing multiple tandem repeat sequences. Electron microscopy of homoduplex DNA molecules containing the human c-Harvey-ras gene revealed knot-like structures which mapped to the position of the 812 bp variable tandem repeat (VTR) sequence. We propose that the structures result from slipped-strand mispairing within the VTR and hybridisation of homologous repetitive sequences in the single-stranded loops so produced. Similar structures were also found in freshly-linearized supercoiled plasmids. More complex knot-like structures were found in homoduplexes of a 4 kb tandem array from the hypervariable region 3' to the human alpha-globin locus. Formation of such DNA tertiary structures in vitro also provides a practical method for identifying and mapping direct tandem repeat arrays that are at least 800 bp long.
authors.affiliation: Beatson Institute for Cancer Research, Bearsden, Glasgow, UK.
authors.forename: L W
authors.initials: LW
authors.lastname: Coggins
authors.forename: M
authors.initials: M
authors.lastname: O'Prey
mesh_terms: D003001:Cloning, Molecular; D004247:DNA; D004278:DNA, Superhelical; D011905:Genes, ras; D005914:Globins / Q000235:genetics*; D006801:Humans; D008854:Microscopy, Electron; D009690:Nucleic Acid Conformation; D009693:Nucleic Acid Hybridization; D010957:Plasmids; D012091:Repetitive Sequences, Nucleic Acid; D015183:Restriction Mapping
chemical_list: D004278:DNA, Superhelical; D005914:Globins; D004247:DNA