The propeller DNA conformation of poly(dA).poly(dT)

Joan Aymami, Miquel Coll, Christin A. Frederick, Andrew H.J. Wang, Alexander Rich

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63 Citations (Scopus)


Physical properties of the DNA duplex, poly(dA).poly(dT) differ considerably from the alternating copolymer poly(dAT). A number of molecular models have been used to describe these structures obtained from fiber X-ray diffraction data. The recent solutions of single crystal DNA dodecamer structures with segments of oligo-A.oligo-T have revealed the presence of a high propeller twist in the AT regions which is stabilized by the formation of bifurcated (three-center) hydrogen bonds on the floor of the major groove, involving the N6 amino group of adenine hydrogen bonding to two 04 atoms of adjacent thymine residues on the opposite strand. Here we show that it is possible to incorporate the features of the single crystal analysis, specifically high propeller twist, bifurcated hydrogen bonds, and a narrow minor groove, as well as the close interstrand N signal between adenine HC2 and ribose HC1' of the opposite strand, into a model that is fully compatible with the diffraction data obtained from poly(dA) poly(dT).

Original languageEnglish
Pages (from-to)3229-3245
Number of pages17
JournalNucleic Acids Research
Issue number8
Publication statusPublished - Apr 25 1989
Externally publishedYes

ASJC Scopus subject areas

  • Genetics


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