title: Unexpectedly Streamlined Mitochondrial Genome of the Euglenozoan Euglena gracilis.
abstract: In this study, we describe the mitochondrial genome of the excavate flagellate Euglena gracilis. Its gene complement is reduced as compared with the well-studied sister groups Diplonemea and Kinetoplastea. We have identified seven protein-coding genes: Three subunits of respiratory complex I (nad1, nad4, and nad5), one subunit of complex III (cob), and three subunits of complex IV (cox1, cox2, and a highly divergent cox3). Moreover, fragments of ribosomal RNA genes have also been identified. Genes encoding subunits of complex V, ribosomal proteins and tRNAs were missing, and are likely located in the nuclear genome. Although mitochondrial genomes of diplonemids and kinetoplastids possess the most complex RNA processing machineries known, including trans-splicing and editing of the uridine insertion/deletion type, respectively, our transcriptomic data suggest their total absence in E. gracilis. This finding supports a scenario in which the complex mitochondrial processing machineries of both sister groups evolved relatively late in evolution from a streamlined genome and transcriptome of their common predecessor.
authors.affiliation: Institute of Parasitology, Biology Centre, Czech Academy of Sciences, České Budějovice (Budweis), Czech Republic Departments of Biochemistry and Genetics, Faculty of Natural Sciences, Comenius University, Bratislava, Slovakia.
authors.forename: Eva
authors.initials: E
authors.lastname: Dobáková
authors.affiliation: Institute of Parasitology, Biology Centre, Czech Academy of Sciences, České Budějovice (Budweis), Czech Republic Life Science Research Centre, Faculty of Science, University of Ostrava, Ostrava, Czech Republic.
authors.forename: Pavel
authors.initials: P
authors.lastname: Flegontov
authors.affiliation: Institute of Parasitology, Biology Centre, Czech Academy of Sciences, České Budějovice (Budweis), Czech Republic Faculty of Science, University of South Bohemia, České Budějovice (Budweis), Czech Republic.
authors.forename: Tomáš
authors.initials: T
authors.lastname: Skalický
authors.affiliation: Institute of Parasitology, Biology Centre, Czech Academy of Sciences, České Budějovice (Budweis), Czech Republic Faculty of Science, University of South Bohemia, České Budějovice (Budweis), Czech Republic Canadian Institute for Advanced Research, Toronto, Ontario, Canada jula@paru.cas.cz.
authors.forename: Julius
authors.initials: J
authors.lastname: Lukeš
mesh_terms: D045222:Electron Transport Chain Complex Proteins / Q000235:genetics; D005056:Euglena gracilis / Q000235:genetics*; D019143:Evolution, Molecular; D054629:Genome, Mitochondrial; D017393:RNA Editing; D012326:RNA Splicing; D012335:RNA, Ribosomal / Q000235:genetics; D059467:Transcriptome
chemical_list: D045222:Electron Transport Chain Complex Proteins; D012335:RNA, Ribosomal
keywords: Euglena gracilis; RNA editing; mitochondrial genome; transcription