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. Author manuscript; available in PMC: 2017 Jan 1.
Published in final edited form as: J Cell Physiol. 2016 Jan;231(1):15–24. doi: 10.1002/jcp.25053

Figure 4. Opportunities for mutagenesis during break-induced replication (BIR).

Figure 4

A. Creation of a one-ended double-strand break. B. Resection of broken ends creates 3’ single-stranded DNA (ssDNA) that can be easily damaged. C. One-ended strand invasion into a homologous template creates a displacement (D)-loop. Synthesis during D-loop extension in BIR is highly mutagenic. D. Migration of the D-loop results in extensive accumulation of ssDNA. Unwinding of the D-loop prior to completion of synthesis and re-invasion into homeologous or microhomologous sequences can result in insertion/deletion mutations. E. Processive synthesis up to hundreds of kilobases to the end of a chromosome and accumulation of more ssDNA, which is easily damaged. F. Completion of repair via lagging strand synthesis. G. DNA damage or genetic impairment of BIR can stall repair synthesis. H. Subsequent resolution of the blocked replication fork results in a half crossover (HCO) event. I. Re-invasion of the broken template can result in subsequent rounds of BIR. Asterisks indicate new potential sites of mutagenesis at each successive step.