2MB4: Solution Structure Of A Stacked Dimeric G-quadruplex Formed By A Segment Of The Human Ceb1 Minisatellite

CEB1 is a highly polymorphic human minisatellite. In yeast, the size variation of CEB1 tandem arrays has been associated with the capacity of the motif to form G-quadruplexes. Here we report on the NMR solution structure of a G-quadruplex formed by the CEB1 DNA G-rich fragment d(AGGGGGGAGGGAGGGTGG), harboring several G-tracts including one with six continuous guanines. This sequence forms a dimeric G-quadruplex involving the stacking of two subunits, each being a unique snapback parallel-stranded scaffold with three G-tetrad layers, three double-chain-reversal loops, and a V-shaped loop. The two subunits are stacked at their 5'-end tetrads, and multiple stacking rotamers may be present due to a high symmetry at the stacking interface. There is a conformational exchange in the millisecond time scale involving a swapping motion between two bases of the six-guanine tract. Our results not only add to the understanding of how the G-quadruplex formation in human minisatellite leads to genetic instability but also address the fundamental questions regarding stacking of G-quadruplexes and how a long continuous G-tract participates in the structure and conformational dynamics of G-quadruplexes.
PDB ID: 2MB4Download
MMDB ID: 120172
PDB Deposition Date: 2013/7/25
Updated in MMDB: 2014/05
Experimental Method:
solution nmr
Source Organism:
Biological Unit for 2MB4: dimeric; determined by author
Molecular Components in 2MB4
Label Count Molecule
Nucleotide(1 molecule)
DNA_(5'- D(*ap*gp*gp*gp*gp*gp*gp*ap*gp*gp*gp*ap*gp*gp*gp*tp*gp*g)-3')
Molecule annotation
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