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. Author manuscript; available in PMC: 2015 Jun 3.
Published in final edited form as: Nat Struct Mol Biol. 2009 Jan 11;16(2):159–167. doi: 10.1038/nsmb.1544

Figure 1.

Figure 1

CAG•CTG repeats show increased fragility in the absence of Srs2 or Sgs1 helicases. Molecular analysis of YACs purified from FOAR colonies, in both wild-type and mutant strains, showed that the rate of FOAR is correlated with YAC breakage (data not shown; see also ref. 26). (a) Experimental system. If the YAC undergoes breakage at or near the trinucleotide repeat tract, the distal DNA fragment containing the URA3 gene is lost and cells become resistant to 5-fluoroorotic acid (FOAR). Broken YACs can be recovered by addition of a new telomere onto the 108-bp T4G4/C4A4 telomere seed sequence (TEL). (b,c) Rate of FOAR for cells with YACs containing no repeat (CAG•CTG)0, a (CAG)70 repeat (b) or a (CTG)70 repeat (c). The average of at least three experiments is shown. Error bars indicate s.e.m., and asterisks indicate a significant difference between the wild type and the mutants (pooled t-test: **, P ≤ 0.01; *, P ≤ 0.05). Numbers above each bar represent the fold increase over the wild-type value for the corresponding repeat tract.