DNA octaplex formation with an I-motif of water-mediated A-quartets: reinterpretation of the crystal structure of d(GCGAAAGC).
The crystal structure of the tetragonal form of d(gcGAAAgc) has been revised and reasonably refined including the disordered residues. The two DNA strands form a base-intercalated duplex, and the four duplexes are assembled according to the crystallographic 222 symmetry to form an octaplex. In the central region, the eight strands are associated by I-motif of double A-quartets. Furthermore, eight hydrated-magnesium cations link the four duplexes to support the octaplex formation. Based on these structural features, a proposal that folding of d(GAAA)n, found in the non-coding region of genomes, into an octaplex can induce slippage during replication to facilitate length polymorphism is presented.
Sato
Yoshiteru
Y
Graduate School of Bioscience and Biotechnology, Tokyo Institute of Technology, 4259 Nagatsuda, Midori-ku, Yokohama 226-850.
Mitomi
Kenta
K
Sunami
Tomoko
T
Kondo
Jiro
J
Takénaka
Akio
A
D020029:Base Pairing; D018360:Crystallography, X-Ray; D004247:DNA / Q000737:chemistry*; D018598:Minisatellite Repeats; D009690:Nucleic Acid Conformation; D009838:Oligodeoxyribonucleotides / Q000737:chemistry*; D014867:Water / Q000737:chemistry
D009838:Oligodeoxyribonucleotides; D014867:Water; D004247:DNA