FIG. 8.

Destabilization of the 5BSL3.2 upper helix by C84A/U86G. RNA structure probing was used to examine the 5BSL3.2 structure for mutants C84A/U86G, C84A/U86A, and U86G. RNAs were treated with RNase T₁ (1 U), RNase V₁ (0.1 U), or lead(II) (15 and 30 mM) followed by primer extension analysis (see Materials and Methods). cDNA products were resolved on a 12% PAGE-7 M urea denaturing gel. Unique T₁ cleavages observed for mutant C84A/U86G RNA are indicated by arrows. At the right, the locations of these cleavages are also shown on the secondary structure model of 5BSL3.2.