Sequence analysis of the mitochondrial genome of Sarcophyton glaucum: conserved gene order among octocorals

• Published in: Journal of molecular evolution 1998-12, Vol.47 (6), p.697-708
• Main Authors: Beaton, M J, Roger, A J, Cavalier-Smith, T
• Format: Article
• Language: English
• Subjects: Amino Acid Sequence; Amino acids; Animals; Base Composition; Base Sequence; Chromosome Mapping; Cnidaria; Cnidaria - genetics; Codon, Initiator - genetics; Codon, Terminator - genetics; Conserved Sequence; DNA, Mitochondrial - chemistry; DNA, Mitochondrial - genetics; Evolution, Molecular; Evolutionary biology; Genome; Genomics; Marine; Metazoa; Metridium senile; Mitochondrial DNA; Molecular Sequence Data; Plant biology; Proteins - genetics; Renilla; RNA, Ribosomal - genetics; Sarcophyton glaucum; Sequence Homology, Nucleic Acid; Space life sciences; Species Specificity
• ISSN: 0022-2844; 1432-1432
• DOI: 10.1007/pl00006429

The nucleotide sequence for an 11,715-bp segment of the mitochondrial genome of the octocoral Sarcophyton glaucum is presented, completing the analysis of the entire genome for this anthozoan member of the phylum Cnidaria. The genome contained the same 13 protein-coding and 2 ribosomal RNA genes as in other animals. However, it also included an unusual mismatch repair gene homologue reported previously and codes for only a single tRNA gene. Intermediate in length compared to two other cnidarians (17,443 and 18,911 bp), this organellar genome contained the smallest amount of noncoding DNA (428, compared to 1283 and 781 nt, respectively), making it the most compact one found for the phylum to date. The mitochondrial genes of S. glaucum exhibited an identical arrangement to that found in another octocoral, Renilla kolikeri, with five protein-coding genes in the same order as has been found in insect and vertebrate mitochondrial genomes. Although gene order appears to be highly conserved among octocorals, compared to the hexacoral, Metridium senile, few similarities were found. Like other metazoan mitochondrial genomes, the A + T composition was elevated and a general bias against codons ending in G or C was observed. However, an exception to this was the infrequent use of TGA compared to TGG to code for tryptophan. This divergent codon bias is unusual but appears to be a conserved feature among two rather distantly related anthozoans.