A simulated molecular evolution from minimal catalytic domain of a group I ribozyme.

Catalysis of Group I intron ribozymes is carried out by its core region consisting of two helical domains P4-P6 and P3-P7. Recently, our laboratory showed that a mutant Group I ribozyme lacking both the P4-P6 domain and the base-triples can perform the trans-esterification reactions. The result demonstrates that the elements required for splicing are concentrated in the P3-P7 domain. Based on this result, we carried out in vitro selection experiment starting from newly constructed libraries in the ribozyme lacking the P4-P6 domain and the base-triples. This selection experiment showed unexpected divergency on the limited sequence space for the active ribozymes.