The RNA∶DNA hybrid and gene conversion at the highly transcribed Sμ.

A. A model depicting two alternate pathways of G-loop formation. In absence of RNase H activity, RNA∶DNA hybrid accumulation fosters folding of G-runs into G4 DNA. In absence of Top1 activity, G4 DNA, which function as a sink for negative torsional stress, can promote RNA∶DNA hybrid formation. B. The rates of gene conversion at pTET-lys2-GTOP (gray bar) or –GBTM (hashed bar) cassette. Indicated strains were transformed with either pGAL1-RNH1 (+RNH1) or pRS416 as vector control. RNHΔ* indicates rnh1Δ rnh201Δ double mutant strains. The 95% confidence intervals are indicated by the error bars.