Group II introns break new boundaries: presence in a bilaterian's genome

Group II introns are ribozymes, removing themselves from their primary transcripts, as well as mobile genetic elements, transposing via an RNA intermediate, and are thought to be the ancestors of spliceosomal introns. Although common in bacteria and most eukaryotic organelles, they have never been r...

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Bibliographic Details
Published in:PloS one 2008-01, Vol.3 (1), p.e1488-e1488
Main Authors: Vallès, Yvonne, Halanych, Kenneth M, Boore, Jeffrey L
Format: Article
Language:English
Subjects:
Animal genetics
Animals
Annelida - classification
Annelida - genetics
Anthozoa
Automation
Bacteria
Base Sequence
Bioinformatics
Catalytic RNA
Cnidaria
Cytochrome
Deoxyribonucleic acid
DNA
DNA Primers
DNA, Mitochondrial - genetics
Evolutionary Biology/Genomics
Fungi
Gene transfer
Genes
Genome
Genomes
Genomics
Germplasm
Introns
Laboratories
Mitochondria
Mitochondrial DNA
Molecular biology
Molecular Biology/Molecular Evolution
Nephtys
Organelles
Phylogenetics
Phylogeny
Ribonucleic acid
Ribozymes
RNA
Transposons
Trichoplax adhaerens
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Summary:Group II introns are ribozymes, removing themselves from their primary transcripts, as well as mobile genetic elements, transposing via an RNA intermediate, and are thought to be the ancestors of spliceosomal introns. Although common in bacteria and most eukaryotic organelles, they have never been reported in any bilaterian animal genome, organellar or nuclear. Here we report the first group II intron found in the mitochondrial genome of a bilaterian worm. This location is especially surprising, since animal mitochondrial genomes are generally distinct from those of plants, fungi, and protists by being small and compact, and so are viewed as being highly streamlined, perhaps as a result of strong selective pressures for fast replication while establishing germ plasm during early development. This intron is found in the mtDNA of an annelid worm, (an undescribed species of Nephtys), where the complete sequence revealed a 1819 bp group II intron inside the cox1 gene. We infer that this intron is the result of a recent horizontal gene transfer event from a viral or bacterial vector into the mitochondrial genome of Nephtys sp. Our findings hold implications for understanding mechanisms, constraints, and selective pressures that account for patterns of animal mitochondrial genome evolution.
ISSN:1932-6203
1932-6203
DOI:10.1371/journal.pone.0001488