Making ends meet: a model for RNA splicing in fungal mitochondria

Abstract
Based on available nucleotide sequence and genetic data, a model for RNA splicing in fungal mitochondria is presented. Seven intron RNA of 2 fungal species [Aspergillus nidulans and Saccharomyces cerevisiae] can form identical secondary structures, involving 4 conserved sequences, which bring the ends of each intron together and allow an internal guide RNA sequence to pair with exon bases adjacent to the splice junctions. The splicing sites are thus aligned precisely within a conserved structure, which could present specific recognition signals to the proteins that catalyze the splicing reaction.