Bidirectional effectors of a group I intron ribozyme from Pneumocystis carinii.

The L-arginine acts stereoselectively on the Pc1.LSU nuclear group I intron of Pneumocystis carinii, competitively inhibiting the first step of the splicing reaction and stimulating the second step. A number of arginine-related compounds are more potent than L-arginine as stimulators and inhibitors. The most potent peptides tested are 10,000 times as effective as L-arginine in inhibiting ribozyme activity, and nearly 400 times as effective as stimulators. This phenomenon indicates that ribozymes, like protein enzymes, can interact with non-substrate low molecular weight compounds, and that non-nucleic acid agents might be developed as drugs acting on RNA targets.