title: Computational screen for spliceosomal RNA genes aids in defining the phylogenetic distribution of major and minor spliceosomal components.
abstract: The RNA molecules of the spliceosome are critical for specificity and catalysis during splicing of eukaryotic pre-mRNA. In order to examine the evolution and phylogenetic distribution of these RNAs, we analyzed 149 eukaryotic genomes representing a broad range of phylogenetic groups. RNAs were predicted using high-sensitivity local alignment methods and profile HMMs in combination with covariance models. The results provide the most comprehensive view so far of the phylogenetic distribution of spliceosomal RNAs. RNAs were predicted in many phylogenetic groups where these RNA were not previously reported. Examples are RNAs of the major (U2-type) spliceosome in all fungal lineages, in lower metazoa and many protozoa. We also identified the minor (U12-type) spliceosomal U11 and U6atac RNAs in Acanthamoeba castellanii, where U12 spliceosomal RNA as well as minor introns were reported recently. In addition, minor-spliceosome-specific RNAs were identified in a number of phylogenetic groups where previously such RNAs were not observed, including the nematode Trichinella spiralis, the slime mold Physarum polycephalum and the fungal lineages Zygomycota and Chytridiomycota. The detailed map of the distribution of the U12-type RNA genes supports an early origin of the minor spliceosome and points to a number of occasions during evolution where it was lost.
authors.affiliation: Department of Medical Biochemistry and Cell Biology, Institute of Biomedicine, Sahlgrenska Academy, University of Gothenburg, Box 462, SE-405 30 Göteborg, Sweden.
authors.forename: Marcela
authors.initials: M
authors.lastname: Dávila López
authors.forename: Magnus Alm
authors.initials: MA
authors.lastname: Rosenblad
authors.forename: Tore
authors.initials: T
authors.lastname: Samuelsson
mesh_terms: D000818:Animals; D001483:Base Sequence; D008411:Chytridiomycota / Q000235:genetics; D019295:Computational Biology / Q000379:methods; D019143:Evolution, Molecular; D005658:Fungi / Q000235:genetics; D023281:Genomics; D008390:Markov Chains; D008969:Molecular Sequence Data; D010802:Phylogeny; D016839:Physarum polycephalum / Q000235:genetics; D012342:RNA, Small Nuclear / Q000737:chemistry / Q000145:classification* / Q000235:genetics; D016415:Sequence Alignment; D017381:Spliceosomes / Q000737:chemistry*; D017160:Trichinella spiralis / Q000235:genetics
chemical_list: D012342:RNA, Small Nuclear; C405482:U4 small nuclear RNA