Reversion spectra in rnh201Δ backgrounds under high-transcription conditions.
A... pTET-lys2ΔBgl revertants. B... pTET-lys2ΔA746 revertants. C... pTET-lys2ΔA746,NR revertants. In each spectrum, 2- or 4-bp deletions at the Top1-dependent hotspot are highlighted gray; QP mutations at the Top1-independent hotspot are highlighted yellow. “N” refers to the number of Lys+ revertants sequenced for each spectrum; “Δ” and “+” signify a 1-bp deletion and insertion, respectively; cpx represents sporadic complex events that are not at the QP hotspot. The types and proportions of QP events at the hotspot in each spectrum are indicated. Arrows above the sequences correspond to inverted repeats; red bases indicate the positions and types of sequence changes in the QP events. It should be noted that some of the QP mutation types were not identified in the spectra shown and only became prominent when additional mutations were introduced. The proportions of QP mutation types identified in other genetic backgrounds are provided in Tables S1, S2, S3.