Effect of nonwobble anticodon deoxynucleosides on γ-toxin activity in vitro. The 17-mer oligonucleotide substrates corresponding to the anticodon stem–loop of tRNAGlu are shown. The R17 substrate is all-RNA. The dU-9 and dC-10 substrates contain single deoxynucleosides in the UUC anticodon triplet, as indicated. Nuclease reaction mixtures (10 μL) contained 200 fmol 5′ 32P-labeled 17-mer substrates and γ-toxin as specified. The products were analyzed by denaturing PAGE. Reaction of γ-toxin with the R17, dU9, and dC-10 substrate yielded single 32P-labeled 8-mer cleavage products of identical electrophoretic mobility (data not shown). The extents of 17-mer cleavage are plotted as a function of input γ-toxin.
