title: Trmt61B is a methyltransferase responsible for 1-methyladenosine at position 58 of human mitochondrial tRNAs.
abstract: In human mitochondria, 1-methyladenosine (m¹A) occurs at position 58 of tRNA(Leu(UUR)). In addition, partial m¹A58 modifications have been found in human mitochondrial tRNA(Lys) and tRNA(Ser(UCN)). We identified human Trmt61B, which encodes a mitochondria-specific tRNA methyltransferase responsible for m¹A58 in these three tRNAs. Trmt61B is dominantly localized to the mitochondria. m¹A58 formation in human mitochondrial tRNA(Leu(UUR)) could be reconstituted in vitro using recombinant Trmt61B in the presence of Ado-Met as a methyl donor. Unlike the cytoplasmic tRNA m¹A58 methyltransferase that consists of an α2β2 heterotetramer formed by Trmt61A and Trmt6, Trmt61B formed a homo-oligomer (presumably a homotetramer) that resembled the bacterial homotetrameric m¹A58 methyltransferase. The bacterial origin of Trmt61B is supported by the results of the phylogenetic analysis.
authors.affiliation: Department of Chemistry and Biotechnology, Graduate School of Engineering, University of Tokyo, Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan.
authors.forename: Takeshi
authors.initials: T
authors.lastname: Chujo
authors.forename: Tsutomu
authors.initials: T
authors.lastname: Suzuki
mesh_terms: D000241:Adenosine / Q000031:analogs & derivatives* / Q000378:metabolism; D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000235:genetics; D006367:HeLa Cells; D006801:Humans; D008928:Mitochondria / Q000378:metabolism; D008969:Molecular Sequence Data; D009690:Nucleic Acid Conformation; D010802:Phylogeny; D020836:Protein Structure, Quaternary; D012313:RNA / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D000077278:RNA, Mitochondrial; D012343:RNA, Transfer / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D012359:tRNA Methyltransferases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; D000077278:RNA, Mitochondrial; D011994:Recombinant Proteins; C002230:1-methyladenosine; D012313:RNA; D012343:RNA, Transfer; C577855:Trmt61B protein, human; D012359:tRNA Methyltransferases; D000241:Adenosine