Thraustochytrium aureum

Mitochondrial genome organization, gene content, genetic code

The circular mitochondrial genome of Thraustochytrium aureum is about 41.5 kbp in size. The genes are clustered and tightly packed within a 30 kbp stretch, with the remaining 10 kbp comprising a complex series of repeated sequences, including two duplicates of the trnD gene. Transcribed genes are found on one DNA strand only. Proteins are translated using the standard genetic code.

Compared to other protists, Thraustochytrium aureum contains a slightly reduced set of mitochondrial genes, including the protein-coding genes cob, cox1,2,3, nad1,2,3,4,4L,5,6,7,9,11, atp6,8,9, 4 small subunit ribosomal protein genes (rps3,4,12-14), and one large subunit ribosomal protein gene (rpl2). Also, an unidentified gene with similarity to unassigned mitochondrial ORFs in other organisms (ymf16; orf248 in Marchantia mtDNA) is found in this genome.

Structural RNA genes include rnl (large subunit rRNA) and rns (small subunit rRNA) and genes for 17 tRNAs (not counting the duplicate copy of trnD). These mtDNA-encoded tRNAs are presumably supplemented by additional, imported, nuclear DNA-encoded tRNAs to permit translation of all codons in protein-coding genes.

An unusual feature of this genome is the fact that the nad4L and nad1 genes are encoded by a single open reading frame. A similar gene fusion has been found in Acanthamoeba castellanii, where cox1 and cox2 are encoded by a single ORF.

Advocate of this sequencing project: B.F. Lang
Collaborators: G. Burger
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Fungal mtDNAs (FMGP)* | Other complete mtDNAs | Gene names | Mitochondrial Genomics ]