title: Spliceosomal intronogenesis.
abstract: The presence of intervening sequences, termed introns, is a defining characteristic of eukaryotic nuclear genomes. Once transcribed into pre-mRNA, these introns must be removed within the spliceosome before export of the processed mRNA to the cytoplasm, where it is translated into protein. Although intron loss has been demonstrated experimentally, several mysteries remain regarding the origin and propagation of introns. Indeed, documented evidence of gain of an intron has only been suggested by phylogenetic analyses. We report the use of a strategy that detects selected intron gain and loss events. We have experimentally verified, to our knowledge, the first demonstrations of intron transposition in any organism. From our screen, we detected two separate intron gain events characterized by the perfect transposition of a reporter intron into the yeast genes RPL8B and ADH2, respectively. We show that the newly acquired introns are able to be removed from their respective pre-mRNAs by the spliceosome. Additionally, the novel allele, RPL8Bint, is functional when overexpressed within the genome in a strain lacking the Rpl8 paralogue RPL8A, demonstrating that the gene targeted for intronogenesis is functional.
authors.affiliation: Graduate Program in Cellular and Molecular Biology, The University of Texas at Austin, Austin, TX 78712;
authors.forename: Sujin
authors.initials: S
authors.lastname: Lee
authors.affiliation: Department of Molecular Biosciences, The University of Texas at Austin, Austin, TX 78712; Institute for Cellular and Molecular Biology, The University of Texas at Austin, Austin, TX 78712 scott.stevens@austin.utexas.edu.
authors.forename: Scott W
authors.initials: SW
authors.lastname: Stevens
mesh_terms: D000426:Alcohol Dehydrogenase / Q000235:genetics; D019143:Evolution, Molecular; D005800:Genes, Fungal; D017930:Genes, Reporter; D007438:Introns; D008957:Models, Genetic; D010802:Phylogeny; D012331:RNA, Fungal / Q000235:genetics; D012333:RNA, Messenger / Q000235:genetics; D012269:Ribosomal Proteins / Q000235:genetics; D012441:Saccharomyces cerevisiae / Q000235:genetics; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics; D017381:Spliceosomes / Q000235:genetics*
chemical_list: D012331:RNA, Fungal; D012333:RNA, Messenger; D012269:Ribosomal Proteins; D029701:Saccharomyces cerevisiae Proteins; C056368:ribosomal protein L4; C509911:ADH2 protein, S cerevisiae; D000426:Alcohol Dehydrogenase
keywords: evolution; intron; spliceosome