Figure 1: A novel genomic selection-based assay to measure G4 DNA instability.
(a) Schematic representation of a G-quadruplex structure. (b) DNA sequences that were targeted to the endogenous unc-22 locus. The guanines that can participate in the formation of a G-quadruplex structure are boxed. (c) Schematic representation of the targeting strategy in which a Tc1 transposon-induced double-strand break in the unc-22 locus is allowed to repair via an extrachromosomal array carrying ~3 kb unc-22 sequences interspersed with a G4 motif. The intervening sequence was designed to result in a functional unc-22 ORF upon integration. (d) dog-1- and G4 DNA-dependent mutation induction for the endogenous unc-22. The frequency is based on ±40 independent populations per genotype; the mean of at least two experiments is shown. Error bars indicate s.e.m. (e) Comparison of G4 DNA-induced deletion frequencies at the unc-22 locus for different G4 sequence motifs. The frequency is based on ±40 independent populations per genotype; the mean of at least two experiments is shown. Error bars indicate s.e.m. (f) Graphic illustration of the G4 deletion profiles of different G4 motifs; each bar represents one mutant. (g) G4 DNA-induced deletion frequencies for the indicated genetic backgrounds. The fold induction with respect to dog-1 unc-22(G4e) is represented, and is based on at least two independent experiments. Error bars indicate s.e.m. No significant (n.s.) difference was found between dog-1 single and double mutants (paired two-tailed t-test).
