Molecular evolution of disrupted transfer RNA genes and their introns in Archaea

Transfer RNA (tRNA) is one of the classical non-coding RNAs and is essential for decoding the genomic sequence into proteins. The disrupted tRNA genes in the genomes of the Archaea have been studied in recent years and three unique examples have been found: multiple-intron-containing tRNAs, split tRNAs, and permuted tRNAs. During this research, it was noted that frequent intron transpositions might have occurred among the tRNA genes in the Archaea. Because these tRNAs are encoded as precursor forms (pre-tRNAs) in the genome, they must be processed to yield mature functional tRNAs. Here, the co-evolutionary history of the tRNA gene architecture and the tRNA splicing enzymes in the domain Archaea are proposed. In this review, I discuss a possible evolutionary scenario for the disrupted tRNAs and their introns.