4PZQ

Crystal Structure of CCG DNA repeats

Summary for 4PZQ

• Entry DOI: 10.2210/pdb4pzq/pdb
• Descriptor: DNA (5'-D(*TP*CP*CP*GP*CP*CP*GP*CP*CP*GP*A)-3'), COBALT (II) ION (3 entities in total)
• Functional Keywords: i-motif, hemiprotonated cc+ pairs, ccg triplet repeat, dna
• Biological source: Homo sapiens (human)
• Total number of polymer chains: 1
• Total formula weight: 3413.02

Authors

Chen, Y.W.,Hou, M.H. (deposition date: 2014-03-31, release date: 2015-01-07, Last modification date: 2024-03-20)

Primary citation

Chen, Y.W.,Jhan, C.R.,Neidle, S.,Hou, M.H.
Structural basis for the identification of an i-motif tetraplex core with a parallel-duplex junction as a structural motif in CCG triplet repeats
Angew.Chem.Int.Ed.Engl., 53:10682-10686, 2014

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.

PubMed: 25139267
DOI: 10.1002/anie.201405637

Experimental method

X-RAY DIFFRACTION (2.24 Å)