title: An evolutionary 'intermediate state' of mitochondrial translation systems found in Trichinella species of parasitic nematodes: co-evolution of tRNA and EF-Tu.
abstract: EF-Tu delivers aminoacyl-tRNAs to ribosomes in the translation system. However, unusual truncations found in some animal mitochondrial tRNAs seem to prevent recognition by a canonical EF-Tu. We showed previously that the chromadorean nematode has two distinct EF-Tus, one of which (EF-Tu1) binds only to T-armless aminoacyl-tRNAs and the other (EF-Tu2) binds to D-armless Ser-tRNAs. Neither of the EF-Tus can bind to canonical cloverleaf tRNAs. In this study, by analyzing the translation system of enoplean nematode Trichinella species, we address how EF-Tus and tRNAs have evolved from the canonical structures toward those of the chromadorean translation system. Trichinella mitochondria possess three types of tRNAs: cloverleaf tRNAs, which do not exist in chromadorean nematode mitochondria; T-armless tRNAs; and D-armless tRNAs. We found two mitochondrial EF-Tu species, EF-Tu1 and EF-Tu2, in Trichinella britovi. T.britovi EF-Tu2 could bind to only D-armless Ser-tRNA, as Caenorhabditis elegans EF-Tu2 does. In contrast to the case of C.elegans EF-Tu1, however, T.britovi EF-Tu1 bound to all three types of tRNA present in Trichinella mitochondria. These results suggest that Trichinella mitochondrial translation system, and particularly the tRNA-binding specificity of EF-Tu1, could be an intermediate state between the canonical system and the chromadorean nematode mitochondrial system.
authors.affiliation: Department of Bioscience and Biotechnology, Okayama University, 3-1-1 Tsushimanaka, Okayama 700-8530, Japan.
authors.forename: Masashi
authors.initials: M
authors.lastname: Arita
authors.forename: Takuma
authors.initials: T
authors.lastname: Suematsu
authors.forename: Arihiro
authors.initials: A
authors.lastname: Osanai
authors.forename: Takashi
authors.initials: T
authors.lastname: Inaba
authors.forename: Haruo
authors.initials: H
authors.lastname: Kamiya
authors.forename: Kiyoshi
authors.initials: K
authors.lastname: Kita
authors.forename: Masahiko
authors.initials: M
authors.lastname: Sisido
authors.forename: Yoh-ichi
authors.initials: Y
authors.lastname: Watanabe
authors.forename: Takashi
authors.initials: T
authors.lastname: Ohtsuki
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D029742:Caenorhabditis elegans Proteins / Q000737:chemistry; D019143:Evolution, Molecular; D015801:Helminth Proteins / Q000737:chemistry / Q000378:metabolism; D008928:Mitochondria / Q000235:genetics*; D008969:Molecular Sequence Data; D009690:Nucleic Acid Conformation; D010444:Peptide Elongation Factor Tu / Q000737:chemistry* / Q000378:metabolism; D014176:Protein Biosynthesis; D012313:RNA / Q000737:chemistry / Q000378:metabolism; D018510:RNA, Helminth / Q000737:chemistry / Q000378:metabolism; D000077278:RNA, Mitochondrial; D012343:RNA, Transfer / Q000737:chemistry* / Q000378:metabolism; D012344:RNA, Transfer, Ala / Q000737:chemistry / Q000378:metabolism; D012362:RNA, Transfer, Ser / Q000737:chemistry / Q000378:metabolism; D012364:RNA, Transfer, Trp / Q000737:chemistry / Q000378:metabolism; D016415:Sequence Alignment; D014234:Trichinella / Q000235:genetics*
chemical_list: D029742:Caenorhabditis elegans Proteins; D015801:Helminth Proteins; D018510:RNA, Helminth; D000077278:RNA, Mitochondrial; D012344:RNA, Transfer, Ala; D012362:RNA, Transfer, Ser; D012364:RNA, Transfer, Trp; D012313:RNA; D012343:RNA, Transfer; D010444:Peptide Elongation Factor Tu