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.