Solution structure of a locked nucleic acid modified quadruplex: introducing the V4 folding topology.

Sharp curves: The structure of a locked nucleic acid modified telomeric sequence from Oxytricha nova displays a remarkable folding topology, distinct from the native O. nova quadruplex. Each guanine stretch folds back in a V-shaped turn that puts the first and fourth guanines in the same tetrad, looping over a tetrad with a sharp turn in the DNA backbone, showing how subtle interplay between sequence and conformation defines the folding topology.