title: Taurine-containing uridine modifications in tRNA anticodons are required to decipher non-universal genetic codes in ascidian mitochondria.
abstract: Variations in the genetic code are found frequently in mitochondrial decoding systems. Four non-universal genetic codes are employed in ascidian mitochondria: AUA for Met, UGA for Trp, and AGA/AGG(AGR) for Gly. To clarify the decoding mechanism for the non-universal genetic codes, we isolated and analyzed mitochondrial tRNAs for Trp, Met, and Gly from an ascidian, Halocynthia roretzi. Mass spectrometric analysis identified 5-taurinomethyluridine (τm(5)U) at the anticodon wobble positions of tRNA(Met)(AUR), tRNA(Trp)(UGR), and tRNA(Gly)(AGR), suggesting that τm(5)U plays a critical role in the accurate deciphering of all four non-universal codes by preventing the misreading of pyrimidine-ending near-cognate codons (NNY) in their respective family boxes. Acquisition of the wobble modification appears to be a prerequisite for the genetic code alteration.
authors.affiliation: Department of Chemistry and Biotechnology, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan.
authors.forename: Takeo
authors.initials: T
authors.lastname: Suzuki
authors.affiliation: Department of Chemistry and Biotechnology, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan.
authors.forename: Kenjyo
authors.initials: K
authors.lastname: Miyauchi
authors.affiliation: Department of Chemistry and Biotechnology, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan. Electronic address: ts@chembio.t.u-tokyo.ac.jp.
authors.forename: Tsutomu
authors.initials: T
authors.lastname: Suzuki
authors.affiliation: Department of Molecular Biology, School of Life Sciences, Tokyo University of Pharmacy and Life Sciences, 1432-1 Horinouchi, Hachioji, Tokyo 192-0392, Japan.
authors.forename: Shin-Ichi
authors.initials: SI
authors.lastname: Yokobori
authors.affiliation: Biomedicinal Research Center, National Institute of Advanced Industrial Science and Technology, 2-4-7 Aomi, Koto-ku, Tokyo 135-0064, Japan.
authors.forename: Naoki
authors.initials: N
authors.lastname: Shigi
authors.affiliation: Institute for Comprehensive Medical Science, Fujita Health University, 1-98 Dengakugakubo, Kutsukake-cho, Toyoake, Aichi 470-1192, Japan.
authors.forename: Akiko
authors.initials: A
authors.lastname: Kondow
authors.affiliation: Department of Medical Genome, Graduate School of Frontier Sciences, University of Tokyo, 5-1-5 Kashiwa, Chiba 277-8652, Japan.
authors.forename: Nono
authors.initials: N
authors.lastname: Takeuchi
authors.affiliation: Department of Molecular Biology, School of Life Sciences, Tokyo University of Pharmacy and Life Sciences, 1432-1 Horinouchi, Hachioji, Tokyo 192-0392, Japan.
authors.forename: Akihiko
authors.initials: A
authors.lastname: Yamagishi
authors.affiliation: Department of Molecular Biology, School of Life Sciences, Tokyo University of Pharmacy and Life Sciences, 1432-1 Horinouchi, Hachioji, Tokyo 192-0392, Japan; Department of Biotechnology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan. Electronic address: kim-wata@toyaku.ac.jp.
authors.forename: Kimitsuna
authors.initials: K
authors.lastname: Watanabe
mesh_terms: D000818:Animals; D000926:Anticodon / Q000235:genetics / Q000378:metabolism*; D008928:Mitochondria / Q000235:genetics / Q000378:metabolism*; D012313:RNA / Q000235:genetics / Q000378:metabolism*; D000077278:RNA, Mitochondrial; D013654:Taurine / Q000235:genetics / Q000378:metabolism*; D014529:Uridine / Q000235:genetics / Q000378:metabolism*; D014561:Urochordata / Q000235:genetics / Q000378:metabolism*
chemical_list: D000926:Anticodon; D000077278:RNA, Mitochondrial; D013654:Taurine; D012313:RNA; D014529:Uridine