title: Extreme RNA editing in coding islands and abundant microsatellites in repeat sequences of Selaginella moellendorffii mitochondria: the root of frequent plant mtDNA recombination in early tracheophytes.
abstract: Using an independent fosmid cloning approach and comprehensive transcriptome analysis to complement data from the Selaginella moellendorffii genome project, we determined the complete mitochondrial genome structure of this spikemoss. Numerous recombination events mediated mainly via long sequence repeats extending up to 7 kbp result in a complex mtDNA network structure. Peculiar features associated with the repeat sequences are more than 80 different microsatellite sites (predominantly trinucleotide motifs). The S. moellendorffii mtDNA encodes a plant-typical core set of a twin-arginine translocase (tatC), 17 respiratory chain subunits, and 2 rRNAs but lacks atp4 and any tRNA genes. As a further novelty among plant chondromes, the nad4L gene is encoded within an intron of the nad1 gene. A total of 37 introns occupying the 20 mitochondrial genes (four of which are disrupted into trans-splicing arrangements including two novel instances of trans-splicing introns) make the S. moellendorffii chondrome the intron-richest and gene-poorest plant mtDNA known. Our parallel transcriptome analyses demonstrates functional splicing of all 37 introns and reveals a new record amount of plant organelle RNA editing with a total of 2,139 sites in mRNAs and 13 sites in the two rRNAs, all of which are exclusively of the C-to-U type.
authors: Abteilung Molekulare Evolution, Institut für Zelluläre und Molekulare Botanik, Universität Bonn, D-53115 Bonn, Germany.
authors: Julia
authors: J
authors: Hecht
authors: Felix
authors: F
authors: Grewe
authors: Volker
authors: V
authors: Knoop
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D004272:DNA, Mitochondrial / Q000235:genetics*; D054629:Genome, Mitochondrial; D007438:Introns; D018895:Microsatellite Repeats; D008928:Mitochondria / Q000235:genetics*; D008969:Molecular Sequence Data; D010940:Plant Proteins / Q000235:genetics; D017393:RNA Editing; D011995:Recombination, Genetic; D032503:Selaginellaceae / Q000235:genetics*
chemical_list: D004272:DNA, Mitochondrial; D010940:Plant Proteins