Trans-activation of the Tetrahymena ribozyme by its P2-2.1 domains.

The Tetrahymena group I self-splicing intron contains peripheral domains P2-2.1. Mutant introns lacking these domains are hardly active. We found that if an independently prepared P2-2.1 RNA is added in trans, it efficiently enhances the catalytic activity of an intron lacking the domains. P2-2.1 RNA together with the previously identified activator, P5abc RNA, of the Tetrahymena intron can activate the intron lacking both of them. The trans-activation depends on the long-range interaction between P2.1 and P9.1 domains.