DNA triple-helix formation at target sites containing duplex mismatches.
We have studied the formation of DNA triple helices at target sites that contain mismatches in the duplex target. Fluorescence melting studies were used to examine a series of parallel triple helices that contain all 64 N.XZ triplet combinations at the centre (where N, X and Z are each of the four natural DNA bases in turn). Similar experiments were also performed with N=bis-amino-U (BAU) (for stable recognition of AT base pairs) and N=S (for recognition of TA inversions). We find that the introduction of a duplex mismatch destabilises the C+.GZ, T.AZ and G.TZ triplets. A similar effect is seen with BAU.AZ triplets. In contrast, other base combinations, based on non-standard triplets such as C.AZ, T.TZ, G.CZ and A.CZ are stabilised by the presence of a duplex mismatch. In each case S binds to sites containing duplex mismatches better than the corresponding Watson-Crick base pairs.
Rusling
David A
DA
School of Biological Sciences, University of Southampton, Bassett Crescent East, Southampton SO16 7PX, UK.
Brown
Tom
T
Fox
Keith R
KR
D020137:Base Pair Mismatch; D001665:Binding Sites; D004247:DNA / Q000737:chemistry*; D006860:Hydrogen Bonding; D008968:Molecular Conformation; D009690:Nucleic Acid Conformation; D009841:Oligonucleotides / Q000737:chemistry; D013696:Temperature
D009841:Oligonucleotides; C051802:triplex DNA; D004247:DNA