engleski

Mitochondrial genes from the marine sponge Suberites domuncula

Mitochondria, the energy-producing organelles of the eukaryotic cell, originate from an endosymbiotic  -proteobacterium. Genome architecture and gene content of mitochondrial DNA (mtDNA) vary extensively throughout eukaryotes. New insights into early mitochondrial genome evolution come from the investigation of primitive mitochondriate eukaryotes, as well as from the comparison between mitochondria and intracellular bacterial symbionts. In this work, the size of circular mitochondrial (mt) genome from the marine sponge Suberites domuncula (Porifera, Demospongiae), representative of the oldest and most simple metazoan phylum, was defined to be ~25 kilobases (kb). Primary structure of 2 portions of mtDNA (>14 kb in total ; >55% of the mt genome) was analysed and the DNA sequences of 8 complete and 2 incomplete protein genes, 12 genes for transfer RNAs and a 3' portion od 16S ribosomal RNA gene were determined. In its compact organisation and well-conserved animal-like gene order this poriferan mtDNA resembles those of the other Metazoa. However, mt genome in sponge S. domuncula contains the gene for subunit 9 of the F0-ATP synthase (located in the nucleus in all other multicellular animals) and encodes bacterial-like ribosomal and transfer RNAs. The genetic code in S. domuncula mt genes is minimally derived and only the UGA termination codon is used to code for triptophan.

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