Figure 8.

DMS probing of the upstream element of the long distance interaction. (A) Wild-type unspliced and Rev-spliced RNAs were denatured, then incubated in the presence of dimerization buffer at 55°C for the times indicated. DMS was then added (0.5% final concentration) and incubation was continued at 27°C for 2 min. Reactions were stopped and primer extensions were used to visualize the sites of modification as described in Materials and Methods. (B) The increased modification of A192 and flanking cytosines in the Rev RNA samples indicates that this region is less protected when the complementary sequence (543–550 nt in the unspliced RNA) is removed by splicing.