Journal Article

The Mitochondrial Genome of <i>Paraminabea aldersladei</i> (Cnidaria: Anthozoa: Octocorallia) Supports Intramolecular Recombination as the Primary Mechanism of Gene Rearrangement in Octocoral Mitochondrial Genomes

Stephanie A. Brockman and Catherine S. McFadden

in Genome Biology and Evolution

Published on behalf of Society for Molecular Biology and Evolution

Volume 4, issue 9, pages 882-894
Published in print January 2012 |
Published online September 2012 | e-ISSN: 1759-6653 | DOI:

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Sequencing of the complete mitochondrial genome of the soft coral Paraminabea aldersladei (Alcyoniidae) revealed a unique gene order, the fifth mt gene arrangement now known within the cnidarian subclass Octocorallia. At 19,886 bp, the mt genome of P. aldersladei is the second largest known for octocorals; its gene content and nucleotide composition are, however, identical to most other octocorals, and the additional length is due to the presence of two large, noncoding intergenic regions. Relative to the presumed ancestral octocoral gene order, in P. aldersladei a block of three protein-coding genes (nad6–nad3–nad4l) has been translocated and inverted. Mapping the distribution of mt gene arrangements onto a taxonomically comprehensive phylogeny of Octocorallia suggests that all of the known octocoral gene orders have evolved by successive inversions of one or more evolutionarily conserved blocks of protein-coding genes. This mode of genome evolution is unique among Metazoa, and contrasts strongly with that observed in Hexacorallia, in which extreme gene shuffling has occurred among taxonomic orders. Two of the four conserved gene blocks found in Octocorallia are, however, also conserved in the linear mt genomes of Medusozoa and in one group of Demospongiae. We speculate that the rate and mechanism of gene rearrangement in octocorals may be influenced by the presence in their mt genomes of mtMutS, a putatively active DNA mismatch repair protein that may also play a role in mediating intramolecular recombination.

Keywords: mtMutS; 28S rDNA; molecular phylogenetics; soft coral; gene inversion

Journal Article.  7868 words.  Illustrated.

Subjects: Bioinformatics and Computational Biology ; Evolutionary Biology ; Genetics and Genomics

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