Download MendeleyStructural basis for the identification of an i-motif tetraplex core with a parallel-duplex junction as a structural motif in CCG triplet repeats
Chen, Y.W., Jhan, C.R., Neidle, S., Hou, M.H.(2014) Angew Chem Int Ed Engl 53: 10682-10686
- PubMed: 25139267
- DOI: https://doi.org/10.1002/anie.201405637
- Primary Citation of Related Structures:
4PZQ - PubMed Abstract:
CCG triplet repeats can fold into tetraplex structures, which are associated with the expansion of (CCG)n trinucleotide sequences in certain neurological diseases. These structures are stabilized by intertwining i-motifs. However, the structural basis for tetraplex i-motif formation in CCG triplet repeats remains largely unknown. We report the first crystal structure of a CCG-repeat sequence, which shows that two dT(CCG)3 A strands can associate to form a tetraplex structure with an i-motif core containing four C:C(+) pairs flanked by two G:G homopurine base pairs as a structural motif. The tetraplex core is attached to a short parallel-stranded duplex. Each hairpin itself contains a central CCG loop in which the nucleotides are flipped out and stabilized by stacking interactions. The helical twists between adjacent cytosine residues of this structure in the i-motif core have an average value of 30°, which is greater than those previously reported for i-motif structures.
Organizational Affiliation:
Institute of Genomics and Bioinformatics and Institute of Biochemistry, National Chung Hsing University, No. 250 Kuo-Kuang Road, Taichung (Taiwan).
