title: Modification at position 9 with 1-methyladenosine is crucial for structure and function of nematode mitochondrial tRNAs lacking the entire T-arm.
abstract: The mitochondria of the nematode Ascaris suum have tRNAs with unusual secondary structures that lack either the T-arm or D-arm found in most other organisms. Of the twenty-two tRNA species present in the mitochondria of A.suum, twenty lack the entire T-arm and two serine tRNAs lack the D-arm. To understand how such unusual tRNAs work in the nematode mitochondrial translation system, we analyzed post-transcriptional modifications of 11 mitochondrial tRNA species purified from A.suum, 10 of which lacked a T-arm and one of which lacked a D-arm. The most characteristic feature of nematode mitochondrial tRNAs lacking a T-arm was the presence of 1-methyladenosine at position 9 (m1A9). Synthesis of T-armless tRNAs with or without the modified nucleoside showed that T-armless tRNAs without the modification had much lower aminoacylation and EF-Tu-binding activities than native tRNAs. The addition of a single methyl group to A9 of these tRNAs was sufficient to restore nearly native levels of aminoacylation and EF-Tu-binding activity as well as tertiary structure, suggesting that m1A9 is a key residue for the activity of T-armless tRNAs. Thus, m1A9 is indispensable for the structure and function of T-armless tRNAs of nematode mitochondrial origin.
authors.affiliation: Department of Integrated Biosciences, Graduate School of Frontier Sciences, The University of Tokyo Kashiwa, Chiba 277-8562, Japan.
authors.forename: Masayuki
authors.initials: M
authors.lastname: Sakurai
authors.forename: Takashi
authors.initials: T
authors.lastname: Ohtsuki
authors.forename: Kimitsuna
authors.initials: K
authors.lastname: Watanabe
mesh_terms: D000241:Adenosine / Q000031:analogs & derivatives* / Q000737:chemistry*; D000818:Animals; D017165:Ascaris suum / Q000235:genetics*; D001483:Base Sequence; D008969:Molecular Sequence Data; D009690:Nucleic Acid Conformation; D009705:Nucleosides / Q000737:chemistry; D010444:Peptide Elongation Factor Tu / Q000378:metabolism; D012313:RNA / Q000737:chemistry* / Q000378:metabolism; D018510:RNA, Helminth / Q000737:chemistry / Q000378:metabolism; D000077278:RNA, Mitochondrial; D012343:RNA, Transfer / Q000737:chemistry* / Q000378:metabolism; D046249:Transfer RNA Aminoacylation
chemical_list: D009705:Nucleosides; D018510:RNA, Helminth; D000077278:RNA, Mitochondrial; C002230:1-methyladenosine; D012313:RNA; D012343:RNA, Transfer; D010444:Peptide Elongation Factor Tu; D000241:Adenosine