Structural Organization of S516 Group I Introns in Myxomycetes
| Autor: | Betty M. N. Furulund, Bård O. Karlsen, Igor Babiak, Peik Haugen, Steinar D. Johansen |
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| Jazyk: | angličtina |
| Rok vydání: | 2022 |
| Předmět: |
catalytic introns
homing endonuclease intron evolution ribozyme twintron Matematikk og Naturvitenskap: 400::Basale biofag: 470::Cellebiologi: 471 [VDP] Genetics Eukaryota Myxomycetes RNA Catalytic Matematikk og Naturvitenskap: 400::Basale biofag: 470::Molekylærbiologi: 473 [VDP] Endonucleases DNA Ribosomal Introns Phylogeny Genetics (clinical) |
| Zdroj: | Genes Genes; Volume 13; Issue 6; Pages: 944 |
| Popis: | Group I introns are mobile genetic elements encoding self-splicing ribozymes. Group I introns in nuclear genes are restricted to ribosomal DNA of eukaryotic microorganisms. For example, the myxomycetes, which represent a distinct protist phylum with a unique life strategy, are rich in nucleolar group I introns. We analyzed and compared 75 group I introns at position 516 in the small subunit ribosomal DNA from diverse and distantly related myxomycete taxa. A consensus secondary structure revealed a conserved group IC1 ribozyme core, but with a surprising RNA sequence complexity in the peripheral regions. Five S516 group I introns possess a twintron organization, where a His-Cys homing endonuclease gene insertion was interrupted by a small spliceosomal intron. Eleven S516 introns contained direct repeat arrays with varying lengths of the repeated motif, a varying copy number, and different structural organizations. Phylogenetic analyses of S516 introns and the corresponding host genes revealed a complex inheritance pattern, with both vertical and horizontal transfers. Finally, we reconstructed the evolutionary history of S516 nucleolar group I introns from insertion of mobile-type introns at unoccupied cognate sites, through homing endonuclease gene degradation and loss, and finally to the complete loss of introns. We conclude that myxomycete S516 introns represent a family of genetic elements with surprisingly dynamic structures despite a common function in RNA self-splicing. |
| Databáze: | OpenAIRE |
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