Fig. 1

Schematic showing G-quadruplex DNA motifs that have different stabilities in model organisms. Examples of PQS sequences, with corresponding schematic structures, taken from the P. falciparum 3D7 genome (an example is shown of one of several structures that each sequence could adopt). Guanine tetrads are shown as green squares and guanine backbones as dashed black lines. Panels a-d demonstrate the four determinants that were shown to promote G4 stability and hence recombination events in vivo in S. cerevisiae: the location of the longest loop (red) being central (a) as opposed to lateral (b); a total loop length of 7 nucleotides or less (c); short loop lengths (blue) of only one or two nucleotides (c); and loops composed of a single pyrimidine (blue, dashed) as opposed to a single purine (green, solid) (d)