Publications

• ALKBH1 is an RNA dioxygenase responsible for cytoplasmic and mitochondrial tRNA modifications.

  Kawarada L., Suzuki T., Ohira T., Hirata S., Miyauchi K., Suzuki T.

  ALKBH1 is a 2-oxoglutarate- and Fe2+-dependent dioxygenase responsible for multiple cellular functions. Here, we show that ALKBH1 is involved in biogenesis of 5-hydroxymethyl-2΄-O-methylcytidine (hm5Cm) and 5-formyl-2΄-O-methylcytidine (f5Cm) at the first position (position 34) of anticodon in cyt ... >> More

  ALKBH1 is a 2-oxoglutarate- and Fe2+-dependent dioxygenase responsible for multiple cellular functions. Here, we show that ALKBH1 is involved in biogenesis of 5-hydroxymethyl-2΄-O-methylcytidine (hm5Cm) and 5-formyl-2΄-O-methylcytidine (f5Cm) at the first position (position 34) of anticodon in cytoplasmic tRNALeu, as well as f5C at the same position in mitochondrial tRNAMet. Because f5C34 of mitochondrial tRNAMet is essential for translation of AUA, a non-universal codon in mammalian mitochondria, ALKBH1-knockout cells exhibited a strong reduction in mitochondrial translation and reduced respiratory complex activities, indicating that f5C34 formation mediated by ALKBH1 is required for efficient mitochondrial functions. We reconstituted formation of f5C34 on mitochondrial tRNAMetin vitro, and found that ALKBH1 first hydroxylated m5C34 to form hm5C34, and then oxidized hm5C34 to form f5C34. Moreover, we found that the frequency of 1-methyladenosine (m1A) in two mitochondrial tRNAs increased in ALKBH1-knockout cells, indicating that ALKBH1 also has demethylation activity toward m1A in mt-tRNAs. Based on these results, we conclude that nuclear and mitochondrial ALKBH1 play distinct roles in tRNA modification. << Less

  Nucleic Acids Res 45:7401-7415(2017) [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.