On the Possibility of an Early Evolutionary Origin for the Spliced Leader Trans-Splicing

• Published in: Journal of molecular evolution Vol. 85; no. 1-2; pp. 37 - 45
• Main Authors: Krchňáková, Zuzana, Krajčovič, Juraj, Vesteg, Matej
• Format: Journal Article
• Language: English
• Published: New York Springer US 01-08-2017; Springer Nature B.V
• Subjects: Analogies; Animal Genetics and Genomics; Binding sites; Biological evolution; Biomedical and Life Sciences; Cell Biology; Conserved sequence; Eukaryota - genetics; Eukaryota - metabolism; Eukaryotes; Evolution, Molecular; Evolutionary Biology; Genomes; Life Sciences; Microbiology; mRNA; Original Article; Phylogeny; Plant Genetics and Genomics; Plant Sciences; Ribonucleic acid; RNA; RNA Precursors - metabolism; RNA processing; RNA, Spliced Leader - genetics; RNA, Spliced Leader - metabolism; Splicing; Structure-function relationships; Trans-Splicing; Spliceosome; Sm-binding site; Intron; RNA secondary structure; SL-RNA
• ISSN: 0022-2844; 1432-1432
• DOI: 10.1007/s00239-017-9803-y

Trans
-splicing is a process by which 5′- and 3′-ends of two pre-RNA molecules transcribed from different sites of the genome can be joined together to form a single RNA molecule. The spliced leader (SL)
trans
-splicing is mediated by the spliceosome and it allows the replacement of 5′-end of pre-mRNA by 5′(SL)-end of SL-RNA. This form of splicing has been observed in many phylogenetically unrelated eukaryotes. Either the SL
trans
-splicing (SLTS) originated in the last eukaryotic common ancestor (LECA) (or even earlier) and it was lost in most eukaryotic lineages, or this mechanism of RNA processing evolved several times independently in various unrelated eukaryotic taxa. The bioinformatic comparisons of SL-RNAs from various eukaryotic taxonomic groups have revealed the similarities of secondary structures of most SL-RNAs and a relative conservation of their splice sites (SSs) and Sm-binding sites (SmBSs). We propose that such structural and functional similarities of SL-RNAs are unlikely to have evolved repeatedly many times. Hence, we favor the scenario of an early evolutionary origin for the SLTS and multiple losses of SL-RNAs in various eukaryotic lineages.