Publications

• Deficient methylation and formylation of mt-tRNA(Met) wobble cytosine in a patient carrying mutations in NSUN3.

  Van Haute L., Dietmann S., Kremer L., Hussain S., Pearce S.F., Powell C.A., Rorbach J., Lantaff R., Blanco S., Sauer S., Kotzaeridou U., Hoffmann G.F., Memari Y., Kolb-Kokocinski A., Durbin R., Mayr J.A., Frye M., Prokisch H., Minczuk M.

  Epitranscriptome modifications are required for structure and function of RNA and defects in these pathways have been associated with human disease. Here we identify the RNA target for the previously uncharacterized 5-methylcytosine (m(5)C) methyltransferase NSun3 and link m(5)C RNA modifications ... >> More

  Epitranscriptome modifications are required for structure and function of RNA and defects in these pathways have been associated with human disease. Here we identify the RNA target for the previously uncharacterized 5-methylcytosine (m(5)C) methyltransferase NSun3 and link m(5)C RNA modifications with energy metabolism. Using whole-exome sequencing, we identified loss-of-function mutations in NSUN3 in a patient presenting with combined mitochondrial respiratory chain complex deficiency. Patient-derived fibroblasts exhibit severe defects in mitochondrial translation that can be rescued by exogenous expression of NSun3. We show that NSun3 is required for deposition of m(5)C at the anticodon loop in the mitochondrially encoded transfer RNA methionine (mt-tRNA(Met)). Further, we demonstrate that m(5)C deficiency in mt-tRNA(Met) results in the lack of 5-formylcytosine (f(5)C) at the same tRNA position. Our findings demonstrate that NSUN3 is necessary for efficient mitochondrial translation and reveal that f(5)C in human mitochondrial RNA is generated by oxidative processing of m(5)C. << Less

  Nat. Commun. 7:12039-12039(2016) [PubMed] [EuropePMC]

• NSUN3 methylase initiates 5-formylcytidine biogenesis in human mitochondrial tRNA(Met).

  Nakano S., Suzuki T., Kawarada L., Iwata H., Asano K., Suzuki T.

  In human mitochondria, the AUA codon encodes methionine via a mitochondrial transfer RNA for methionine (mt-tRNA(Met)) that contains 5-formylcytidine (f(5)C) at the first position of the anticodon (position 34). f(5)C34 is required for deciphering the AUA codon during protein synthesis. Until now, ... >> More

  In human mitochondria, the AUA codon encodes methionine via a mitochondrial transfer RNA for methionine (mt-tRNA(Met)) that contains 5-formylcytidine (f(5)C) at the first position of the anticodon (position 34). f(5)C34 is required for deciphering the AUA codon during protein synthesis. Until now, the biogenesis and physiological role of f(5)C34 were unknown. We demonstrate that biogenesis of f(5)C34 is initiated by S-adenosylmethionine (AdoMet)-dependent methylation catalyzed by NSUN3, a putative methyltransferase in mitochondria. NSUN3-knockout cells showed strong reduction in mitochondrial protein synthesis and reduced oxygen consumption, leading to deficient mitochondrial activity. We reconstituted formation of 5-methylcytidine (m(5)C) at position 34 (m(5)C34) on mt-tRNA(Met) with recombinant NSUN3 in the presence of AdoMet, demonstrating that NSUN3-mediated m(5)C34 formation initiates f(5)C34 biogenesis. We also found two disease-associated point mutations in mt-tRNA(Met) that impaired m(5)C34 formation by NSUN3, indicating that a lack of f(5)C34 has pathological consequences. << Less

  Nat. Chem. Biol. 12:546-551(2016) [PubMed] [EuropePMC]

• NSUN3 and ABH1 modify the wobble position of mt-tRNAMet to expand codon recognition in mitochondrial translation.

  Haag S., Sloan K.E., Ranjan N., Warda A.S., Kretschmer J., Blessing C., Huebner B., Seikowski J., Dennerlein S., Rehling P., Rodnina M.V., Hoebartner C., Bohnsack M.T.

  Mitochondrial gene expression uses a non-universal genetic code in mammals. Besides reading the conventional AUG codon, mitochondrial (mt-)tRNA^M^et mediates incorporation of methionine on AUA and AUU codons during translation initiation and on AUA codons during elongation. We ... >> More

  Mitochondrial gene expression uses a non-universal genetic code in mammals. Besides reading the conventional AUG codon, mitochondrial (mt-)tRNA^M^et mediates incorporation of methionine on AUA and AUU codons during translation initiation and on AUA codons during elongation. We show that the RNA methyltransferase NSUN3 localises to mitochondria and interacts with mt-tRNA^M^et to methylate cytosine 34 (C34) at the wobble position. NSUN3 specifically recognises the anticodon stem loop (ASL) of the tRNA, explaining why a mutation that compromises ASL basepairing leads to disease. We further identify ALKBH1/ABH1 as the dioxygenase responsible for oxidising m⁵C34 of mt-tRNA^M^et to generate an f⁵C34 modification. In vitro codon recognition studies with mitochondrial translation factors reveal preferential utilisation of m⁵C34 mt-tRNA^Met in initiation. Depletion of either NSUN3 or ABH1 strongly affects mitochondrial translation in human cells, implying that modifications generated by both enzymes are necessary for mt-tRNA^M^et function. Together, our data reveal how modifications in mt-tRNA^M^et are generated by the sequential action of NSUN3 and ABH1, allowing the single mitochondrial tRNA^M^et to recognise the different codons encoding methionine. << Less

  EMBO J. 35:2104-2119(2016) [PubMed] [EuropePMC]

  This publication is cited by 1 other entry.