Strand switch models for generating QP mutations.
The QP mutation illustrated is the most frequent event observed with the lys2ΔBgl allele (QP #1 in Figure 1A) and can be generated (A) via an intra-strand switch that occurs during lagging-strand synthesis or (B) when the nascent leading strand switches to the lagging-strand template. Arrowheads correspond to 3′ ends of DNA strands and the NTS strand of LYS2 is indicated. Template bases are black; bases incorporated before the first template switch are in blue; and DNA synthesized after the template switch is red. The wavy line corresponds to an RNA primer on the lagging strand.