title: DNA H form requires a homopurine-homopyrimidine mirror repeat.
abstract: Regular homopurine-homopyrimidine tracts, (dG-dA)n(dT-dC)n and (dG)n(dC)n, undergo a superhelix-induced, strongly pH-dependent, structural transition into a novel DNA conformation, the H form. We have suggested that the H form can arise in any homopurine-homopyrimidine mirror repeat (H palindrome). We have now tested this prediction using a tailored series of plasmids carrying the inserts AAGGGAGAAXGGGGTATAGGGGYAAGAGGGAA, where X and Y may be either A or G, and subject them to two-dimensional gel electrophoresis. In support of our hypothesis, the inserts exhibited facile transitions into the H form for X = Y = G, or X = Y = A, whereas the transition was much more difficult or impossible for the two non-palindromes (X = A, Y = G or X = G, Y = A). We present evidence that the H form is the structural basis for S1-nuclease hypersensitivity.
authors.affiliation: Institute of Molecular Genetics, USSR Academy of Sciences, Moscow.
authors.forename: S M
authors.initials: SM
authors.lastname: Mirkin
authors.forename: V I
authors.initials: VI
authors.lastname: Lyamichev
authors.forename: K N
authors.initials: KN
authors.lastname: Drushlyak
authors.forename: V N
authors.initials: VN
authors.lastname: Dobrynin
authors.forename: S A
authors.initials: SA
authors.lastname: Filippov
authors.forename: M D
authors.initials: MD
authors.lastname: Frank-Kamenetskii
mesh_terms: D000818:Animals; D001483:Base Sequence; D004247:DNA / Q000378:metabolism; D004278:DNA, Superhelical; D004279:DNA, Viral; D004720:Endonucleases / Q000378:metabolism; D006801:Humans; D006863:Hydrogen-Ion Concentration; D009690:Nucleic Acid Conformation; D009858:Oncogenic Viruses / Q000235:genetics; D010957:Plasmids; D011685:Purine Nucleotides; D011742:Pyrimidine Nucleotides; D012091:Repetitive Sequences, Nucleic Acid; D015719:Single-Strand Specific DNA and RNA Endonucleases
chemical_list: D004278:DNA, Superhelical; D004279:DNA, Viral; D011685:Purine Nucleotides; D011742:Pyrimidine Nucleotides; D004247:DNA; D004720:Endonucleases; D015719:Single-Strand Specific DNA and RNA Endonucleases