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. Author manuscript; available in PMC: 2022 Apr 26.
Published in final edited form as: Methods Mol Biol. 2021;2153:307–328. doi: 10.1007/978-1-0716-0644-5_22

Figure 1. Yeast experimental system to investigate BIR.

Figure 1.

A. Schematic of the AM1003 experimental disome system that contains two copies of chromosome III. One copy contains a Gal::HO endonuclease recognition site (black arrow) at MATa and is truncated by insertion of LEU2 and telomere sequence next to MATa. The other copy of chromosome III is full-length and cannot be cut by HO due to presence of a MATα-inc (uncuttable) allele. B. Mechanism of BIR initiation and progression. BIR is initiated by 5’ to 3’ resection of the one-ended DSB, which leads to formation of exposed 3’ ssDNA. The ssDNA end invades into the homologous template initiating DNA synthesis. Leading strand synthesis progresses by a migrating bubble. ssDNA accumulates behind the migrating bubble due to uncoupled leading and lagging strand synthesis. Conservative inheritance of DNA. C. Repair outcomes following DSB initiation in AM1003. The following repair outcomes and their phenotypes are depicted: Gene conversion (Ade+ Leu+), BIR (Ade+ Leu−), Chromosome loss (Ade−red Leu−), and Half crossover (Ade−white Leu−).