title: Mitogenome rearrangement in the cold-water scleractinian coral Lophelia pertusa (Cnidaria, Anthozoa) involves a long-term evolving group I intron.
abstract: Group I introns are genetic insertion elements that invade host genomes in a wide range of organisms. In metazoans, however, group I introns are extremely rare, so far only identified within mitogenomes of hexacorals and some sponges. We sequenced the complete mitogenome of the cold-water scleractinian coral Lophelia pertusa, the dominating deep sea reef-building coral species in the North Atlantic Ocean. The mitogenome (16,150 bp) has the same gene content but organized in a unique gene order compared to that of other known scleractinian corals. A complex group I intron (6460 bp) inserted in the ND5 gene (position 717) was found to host seven essential mitochondrial protein genes and one ribosomal RNA gene. Phylogenetic analysis supports a vertical inheritance pattern of the ND5-717 intron among hexacoral mitogenomes with no examples of intron loss. Structural assessments of the Lophelia intron revealed an unusual organization that lacks the universally conserved ωG at the 3' end, as well as a highly compact RNA core structure with overlapping ribozyme and protein coding capacities. Based on phylogenetic and structural analyses we reconstructed the evolutionary history of ND5-717, from its ancestral protist origin, through intron loss in some early metazoan lineages, and into a compulsory feature with functional implications in hexacorals.
authors.affiliation: RNA and Transcriptomics Group, Department of Medical Biology, Faculty of Health Sciences, University of Tromsø, N-9037 Tromsø, Norway.
authors.forename: Åse
authors.initials: Å
authors.lastname: Emblem
authors.forename: Bård Ove
authors.initials: BO
authors.lastname: Karlsen
authors.forename: Jussi
authors.initials: J
authors.lastname: Evertsen
authors.forename: Steinar D
authors.initials: SD
authors.lastname: Johansen
mesh_terms: D000818:Animals; D001483:Base Sequence; D003063:Cnidaria / Q000145:classification / Q000235:genetics*; D004272:DNA, Mitochondrial / Q000235:genetics; D019143:Evolution, Molecular; D023061:Gene Order; D054629:Genome, Mitochondrial; D040582:Inheritance Patterns; D007438:Introns; D008969:Molecular Sequence Data; D009690:Nucleic Acid Conformation; D010802:Phylogeny; D017422:Sequence Analysis, DNA
chemical_list: D004272:DNA, Mitochondrial