Potential for alternative intron–exon pairings in group II intron RmInt1 from Sinorhizobium meliloti and its relatives

Abstract

Ribozyme constructs derived from group II intron RmInt1 of Sinorhizobium meliloti self-splice in vitro when incubated under permissive conditions, but exon ligation is unusually inefficient when the 5′ exon is truncated close to the IBS2 intron-binding site. One plausible explanation for this observation is the presence of an alternative intron–exon pairing between an intron segment that overlaps with the EBS2 exon-binding site and a 5′ exon site located just distal of IBS2 relative to the splice junction. Strikingly, the existence of this pairing is supported by comparative sequence analysis of introns related to RmInt1.

Keywords

• group II intron
• ribozyme
• self-splicing
• intron–exon pairings