Mitochondrial DNA of the coral Sarcophyton glaucum contains a gene for a homologue of bacterial MutS: a possible case of gene transfer from the nucleus to the mitochondrion.

摘要: The nucleotide sequences of two segments 6,737 ntp and 258 the 18.4-kb circular mitochondrial (mt) DNA molecule soft coral Sarcophyton glaucum (phylum Cnidaria, class Anthozoa, subclass Octocorallia, order Alcyonacea) have been determined. larger segment contains 3′ 191 gene for subunit 1 respiratory chain NADH dehydrogenase (ND1), complete genes cytochrome b (Cyt b), ND6, ND3, ND4L, a bacterial MutS homologue (MSH), 5’ terminal 1,124 large rRNA (1-rRNA). These are arranged in given all transcribed from same strand molecule. smaller 134 ND4 tRNAf-Met gene, these opposite directions. As hexacorallian anthozoan, Metridium senile, mt-genetic code S. is near standard: that is, contrast to situation codes other invertebrate phyla, AGA AGG specify arginine, ATA specifies isoleucine. However, as appears be universal metazoan codes, TGA tryptophan rather than termination. Also, M. senile mt-tRNAf-Met has primary secondary structural features resembling those Escherichia coli initiator tRNA, including standard dihydrouridine Tv(iC loop sequences, mismatched pair at top amino-acyl stem. presence mutS homologue, which not reported occur any known mtDNA, suggests there mismatch repair activity mitochondria. In support this, phylogenetic analysis family protein indicates mtMSH more closely related nuclear DNA-encoded (MSH1) yeast Saccharomyces cerevisiae eukaryotic homologues involved function, or homologues. Regarding possible origin results, together with comparative base composition considerations, absence an MSH mtDNA best hypothesis acquired early evolution octocorals. mitochondria might expected influence rate this organism’s mtDNA.