FIGURE 7.

Mss116p did not promote helix dissociation in vivo. (A) Kinetic mechanism of a natural ribozyme with 4 bp in H1, HP44, which partitions equally between dissociation and re-ligation of bound products (Donahue et al. 2000). Chimeric HP44 mRNAs were coexpressed in yeast with (B) active Mss116p (Δmts), (C) catalytically inactive Mss116p (ΔmtsE268Q), or (D) empty vector. Mss116p expression had no detectable effect on HP44 self-cleavage activity. Plots display results from a representative pair of experiments with functional (▪) and mutationally inactivated (□) chimeric HP44 mRNAs. Reported values represent the mean and standard deviation obtained from two or more pairs of experiments. Intracellular cleavage, ligation, and dissociation rate constants in the absence of Mss116p overexpression were reported previously (Yadava et al. 2001).