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. 2024 Feb 5;20(2):e1010527. doi: 10.1371/journal.pgen.1010527

Fig 1. SSA repair in S. cerevisiae.

Fig 1

SSA repair between divergent repeats. (i) A DSB is created by HO or Cas9 endonucleases between two 205-bp repeated sequences in Tailed (left) and in Tailless (right) strains. In FA Tailed strains the repeated fragments are separated by a 2.6 kb DNA sequence. (ii) DSB ends undergo 5’ to 3’ resection, creating 3’ single-strand DNA tails. (iii) Annealing of single-strand DNA at complementary sequences creates an intermediate with mismatched base pairs from which (iv) the nonhomologous tails are removed by Rad1-Rad10 endonuclease with the assistance of Msh2–Msh3. Depending on how MMs are corrected, there are different possible outcomes of SSA: Mixed repair–some of the seven mismatches are corrected as F, some as A and some are not corrected (a); all MM are repaired as F (b); all MM are repaired as A (c); If mismatches are not corrected, progeny containing both genotypes will result in a sectored colony containing both alleles (d). B. Creation of one-tailed and pseudo-Tailless strains by Cas9 cleavage. C. Location of mismatches (MMs).