MT-TN explained

mitochondrially encoded tRNA asparagine
Hgncid:7493
Symbol:MT-TN
Altsymbols:MTTN
Entrezgene:4570
Refseq:NC_001807
Chromosome:MT

Mitochondrially encoded tRNA asparagine also known as MT-TN is a transfer RNA which in humans is encoded by the mitochondrial MT-TN gene.[1]

Structure

The MT-TN gene is located on the p arm of the non-nuclear mitochondrial DNA at position 12 and it spans 73 base pairs.[2] The structure of a tRNA molecule is a distinctive folded structure which contains three hairpin loops and resembles a three-leafed clover.[3]

Function

MT-TN is a small 73 nucleotide RNA (human mitochondrial map position 5657-5729) that transfers the amino acid asparagine to a growing polypeptide chain at the ribosome site of protein synthesis during translation.

Clinical significance

Ophthalmoplegia

Mutations in MT-TN have been associated with isolated ophthalmoplegia. Ophthalmoplegia is a condition characterized by eye muscle weakness. Common symptoms of the disorder include hearing loss, loss of sensation in the limbs, ataxia, and neuropathy.[4] Multiple mutations of 5692A>G and 5703G>A have been found in patients with ophthalmoplegia.[5] [6] [7] Such mutations in MT-TN resulted in a failure in oxidative phosphorylation and protein synthesis of the mitochondria. In addition, a 5728A>G transition of MT-TN was found to result in a combined deficiency of complex I and IV, with symptoms of failure to thrive, renal failure, and mental retardation.[8]

Complex IV Deficiency

MT-TN mutations have been associated with complex IV deficiency of the mitochondrial respiratory chain, also known as the cytochrome c oxidase deficiency. Cytochrome c oxidase deficiency is a rare genetic condition that can affect multiple parts of the body, including skeletal muscles, the heart, the brain, or the liver. Common clinical manifestations include myopathy, hypotonia, and encephalomyopathy, lactic acidosis, and hypertrophic cardiomyopathy.[9] 5709T>C[10] [11] mutations in MT-TN have been found in patients with the deficiency.

Notes and References

  1. Anderson S, Bankier AT, Barrell BG, de Bruijn MH, Coulson AR, Drouin J, Eperon IC, Nierlich DP, Roe BA, Sanger F, Schreier PH, Smith AJ, Staden R, Young IG . Sequence and organization of the human mitochondrial genome . Nature . 290 . 5806 . 457–65 . April 1981 . 7219534 . 10.1038/290457a0 . 1981Natur.290..457A . 4355527 .
  2. Web site: MT-TN mitochondrially encoded tRNA asparagine [Homo sapiens (human)] - Gene - NCBI ]. www.ncbi.nlm.nih.gov . en.
  3. Web site: tRNA / transfer RNA . Learn Science at Scitable .
  4. Web site: Progressive external ophthalmoplegia . Genetics Home Reference . en.
  5. Hao H, Moraes CT . A disease-associated G5703A mutation in human mitochondrial DNA causes a conformational change and a marked decrease in steady-state levels of mitochondrial tRNA(Asn) . Molecular and Cellular Biology . 17 . 12 . 6831–7 . December 1997 . 9372914 . 10.1128/mcb.17.12.6831. 232539 .
  6. Vives-Bauza C, Del Toro M, Solano A, Montoya J, Andreu AL, Roig M . Genotype-phenotype correlation in the 5703G>A mutation in the tRNA(ASN) gene of mitochondrial DNA . Journal of Inherited Metabolic Disease . 26 . 5 . 507–8 . 2003 . 14518831 . 10.1023/a:1025133629685. 28445072 .
  7. Moraes CT, Ciacci F, Bonilla E, Jansen C, Hirano M, Rao N, Lovelace RE, Rowland LP, Schon EA, DiMauro S . Two novel pathogenic mitochondrial DNA mutations affecting organelle number and protein synthesis. Is the tRNA(Leu(UUR)) gene an etiologic hot spot? . The Journal of Clinical Investigation . 92 . 6 . 2906–15 . December 1993 . 8254046 . 10.1172/JCI116913 . 288494 .
  8. Meulemans A, Seneca S, Lagae L, Lissens W, De Paepe B, Smet J, Van Coster R, De Meirleir L . A novel mitochondrial transfer RNA(Asn) mutation causing multiorgan failure . Archives of Neurology . 63 . 8 . 1194–8 . August 2006 . 16908752 . 10.1001/archneur.63.8.1194 . free .
  9. Web site: Cytochrome c oxidase deficiency . Genetics Home Reference .
  10. Ronchi D, Sciacco M, Bordoni A, Raimondi M, Ripolone M, Fassone E, Di Fonzo A, Rizzuti M, Ciscato P, Cosi A, Servida M, Moggio M, Corti S, Bresolin N, Comi GP . The novel mitochondrial tRNAAsn gene mutation m.5709T>C produces ophthalmoparesis and respiratory impairment . European Journal of Human Genetics . 20 . 3 . 357–60 . March 2012 . 22189266 . 10.1038/ejhg.2011.238 . 3283170 .
  11. Coulbault L, Herlicoviez D, Chapon F, Read MH, Penniello MJ, Reynier P, Fayet G, Lombès A, Jauzac P, Allouche S . A novel mutation in the mitochondrial tRNA Asn gene associated with a lethal disease . Biochemical and Biophysical Research Communications . 329 . 3 . 1152–4 . April 2005 . 15752774 . 10.1016/j.bbrc.2005.02.083 .

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