Download MendeleyInterlocked mismatch-aligned arrowhead DNA motifs.
Kettani, A., Bouaziz, S., Skripkin, E., Majumdar, A., Wang, W., Jones, R.A., Patel, D.J.(1999) Structure 7: 803-815
- PubMed: 10425682
- DOI: https://doi.org/10.1016/s0969-2126(99)80104-x
- Primary Citation of Related Structures:
1B3P - PubMed Abstract:
Triplet repeat sequences are of considerable biological importance as the expansion of such tandem arrays can lead to the onset of a range of human diseases. Such sequences can self-pair via mismatch alignments to form higher order structures that have the potential to cause replication blocks, followed by strand slippage and sequence expansion. The all-purine d(GGA)n triplet repeat sequence is of particular interest because purines can align via G.G, A.A and G.A mismatch formation. We have solved the structure of the uniformly 13C,15N-labeled d(G1-G2-A3-G4-G5-A6-T7) sequence in 10 mM Na+ solution. This sequence adopts a novel twofold-symmetric duplex fold where interlocked V-shaped arrowhead motifs are aligned solely via interstrand G1.G4, G2.G5 and A3.A6 mismatch formation. The tip of the arrowhead motif is centered about the p-A3-p step, and symmetry-related local parallel-stranded duplex domains are formed by the G1-G2-A3 and G4-G5-A6 segments of partner strands. The purine-rich (GGA)n triplet repeat sequence is dispersed throughout the eukaryotic genome. Several features of the arrowhead duplex motif for the (GGA)2 triplet repeat provide a unique scaffold for molecular recognition. These include the large localized bend in the sugar-phosphate backbones, the segmental parallel-stranded alignment of strands and the exposure of the Watson-Crick edges of several mismatched bases.
Organizational Affiliation:
Cellular Biochemistry and Biophysics Program, Memorial Sloan-Kettering Cancer Center, New York, NY 10021, USA.
