Self-splicing of the Tetrahymena group I ribozyme without conserved base-triples

Background: Group I introns share a conserved core region consisting of two domains, P8-P3-P7 and P4-P6, joined by four base-triples. We showed previo usly that the T4 td intron can perform phosphoester transfer reactions at t wo splice sites in the absence of both P4-P6 and the conserved base-triples , whereas it is barely able to perform the intact splicing reaction due to the difficulty of conducting the sequential reactions. Results: Based on previous findings, we constructed a bimolecular ribozyme lacking a large portion of P4-P6 and the base-triples from the Tetrahymena intron, on the assumption that the long-range interactions of the periphera l regions in the two RNAs can compensate for the deteriorated core. The bim olecular ribozyme performed the intact splicing reaction. Conclusion: The present analysis indicates that the base-triples are noness ential, but that LA and the distal part of P4 in P4-P6 are important for co nducting the splicing reaction. The reconstituted self-splicing ribozyme pr ovides an amenable system for analysing the role(s) of elements in the core region in the self-splicing reaction mechanism.