Figure 5.

Increased ribonucleotide incorporation in dnaE_S759N strains due to an RNase HI deficiency. Genomic DNAs from E. coli strains expressing wild-type dnaE (marked as ‘S’ in the figure) or dnaE_S759N allele (‘N’) in different combinations with RNase HII– (ΔrnhB, ‘–’), HI–deficiency (rnhA339), or impaired proofreading of the replicase (dnaQ920), were isolated, treated with purified RNase HII, and separated in alkaline agarose gel as described in Materials and Methods. 500 ng DNA was loaded per lane. Electrophoresis migration patterns (A) were converted to densitometry curves (B) as described in Materials & Methods. Untreated controls separated in non-denaturing (1× TAE) buffer are shown in Supplementary Figure S7.