Characterization of the newly constructed domains that replace P5abc within the Tetrahymena ribozyme.

The P5abc domain of the Tetrahymena ribozyme has been shown to function as an activator that enhances core catalytic activity of the ribozyme. We reported previously that several new domains in that their primary sequences are different from that of P5abc are also capable of activating the ribozyme. It was unclear whether the mechanism of activation by the new domains is identical to that by P5abc. We have investigated structural and functional properties of the new domains and obtained evidence that strongly indicates that a particular domain activates the ribozyme in a different manner from that by P5abc.