Self-association of telomeric short oligodeoxyribonucleotides containing a dG cluster.
Oligonucleotides containing a dG cluster, d(TmGnTm), are models of single-stranded parts of telomeric deoxyribonucleic acid and substitutes for poly(dG). Electrophoretic and spectroscopic analyses of the oligomers indicate that the oligomers can form two alternative structures, single- and quadruple-stranded helices, in solution at room temperature. The transformation of the single-strandef form into the quadruple-stranded form or vice versa is undetectable in 0.1 M NaCl at 4.3 x 10(-5) M strand concentration at room temperature. However, at a 50-fold higher strand concentration, the single-stranded oligomer is gradually converted into the quadruplex. An increase in ionic strength stabilizes the single-stranded structure, so it seems to inhibit the formation of the quadruplex. The quadruplex, [d(TTGGGGTT)]4, is resistant to denaturation in 7 M urea, in which the Watson-Crick type d(TTGGGGTT).d(AACCCCAA) duplex dissociates. An increase in the number of T residues facilitates the dissociation of the quadruplex by heating. Thus the number of T residues surrounding the dG cluster might control the rigidity of the quadruplex structure.
Shida
T
T
Department of Applied Biology, Faculty of Textile Science and Technology, Shinshu University, Nagano, Japan.
Yokoyama
K
K
Tamai
S
S
Sekiguchi
J
J
D000818:Animals; D001483:Base Sequence; D006147:Guanine / Q000737:chemistry*; D008969:Molecular Sequence Data; D009838:Oligodeoxyribonucleotides / Q000737:chemistry* / Q000235:genetics; D016813:Oxytricha / Q000235:genetics; D016615:Telomere / Q000502:physiology*; D013768:Tetrahymena / Q000235:genetics
D009838:Oligodeoxyribonucleotides; D006147:Guanine