Effect of different nontemplate strand trinucleotide substitutions on Mfd-mediated RNA release. The indicated nontemplate strand DNA substitutions were used in release experiments in comparison with homoduplex wild-type DNA; the percentage of release relative to homoduplex DNA is shown. Black bars, heteroduplex series 1 (upper row of trinucleotide substitutions), experiment 1; gray bars, heteroduplex series 1 (upper row of trinucleotide substitutions), experiment 2; hatched bars, heteroduplex series 2 (lower row of trinucleotide substitutions). The incubation time was 1 min.