FIG. 7.

Analysis of RNA-DNA hybrids in RNase H-defective NCs. Viral core DNA isolated from the RNase H-defective mutant (RH⁻) or the WT was treated with RNase H (RH) (lanes 3 and 7) or buffer alone (lanes 2 and 6) or heat denatured at 95°C (lanes 4 and 8) and then analyzed by Southern blot hybridization using a riboprobe specific for the 5′ end of the minus-strand DNA (as in Fig. 5C). RC, relaxed circular DNA; SS, full-length single-stranded DNA. The marker DNA (SS, heat-denatured, single-stranded DNA; DS, double-stranded DNA) sizes are indicated. In addition to the predicted RNA-DNA hybrid present in the RH⁻ mutant (lanes 1 and 2), an apparent RNA-DNA hybrid (*) was also present in the WT core DNA (lanes 5 and 6) and was converted to a faster-migrating short minus-strand DNA (**) after RNase H digestion (lane 7) or heating (lane 8).