Recognition of exon-intron boundaries by the Halobacterium volcanii tRNA intron endonuclease

Pre-tRNA splicing: variation on a theme or exception to the rule?

There has been a growing recognition that there are many conserved features among apparently diverse RNA splicing systems, suggesting that they may have a common origin. However, pre-tRNA splicing is an apparent exception in nearly all respects. Features of this unique class should be considered in any comprehensive discussion of the origin(s) of splicing and its implications for the evolution of gene structure.

Protein-coding introns from the 23S rRNA-encoding gene form stable circles in the hyperthermophilic archaeon Pyrobaculum organotrophum

Two archaeal introns have been discovered in the single-copy 23S rRNA-encoding gene of the hyperthermophile, Pyrobaculum organotrophum. After excision from rRNA transcripts, both introns circularize and are stably retained in the cell. Putative proteins encoded by the introns and covering most of the intron sequence share a decapeptide motif with proteins encoded by another archaeal intron and by group I introns.