title: A unique tRNA recognition mechanism of Caenorhabditis elegans mitochondrial EF-Tu2.
abstract: Nematode mitochondria expresses two types of extremely truncated tRNAs that are specifically recognized by two distinct elongation factor Tu (EF-Tu) species named EF-Tu1 and EF-Tu2. This is unlike the canonical EF-Tu molecule that participates in the standard protein biosynthesis systems, which basically recognizes all elongator tRNAs. EF-Tu2 specifically recognizes Ser-tRNA(Ser) that lacks a D arm but has a short T arm. Our previous study led us to speculate the lack of the D arm may be essential for the tRNA recognition of EF-Tu2. However, here, we showed that the EF-Tu2 can bind to D arm-bearing Ser-tRNAs, in which the D-T arm interaction was weakened by the mutations. The ethylnitrosourea-modification interference assay showed that EF-Tu2 is unique, in that it interacts with the phosphate groups on the T stem on the side that is opposite to where canonical EF-Tu binds. The hydrolysis protection assay using several EF-Tu2 mutants then strongly suggests that seven C-terminal amino acid residues of EF-Tu2 are essential for its aminoacyl-tRNA-binding activity. Our results indicate that the formation of the nematode mitochondrial (mt) EF-Tu2/GTP/aminoacyl-tRNA ternary complex is probably supported by a unique interaction between the C-terminal extension of EF-Tu2 and the tRNA.
authors.affiliation: Department of Integrated Bioscience, Graduate School of Frontier Science, The University of Tokyo 5-1-5 Kashiwanoha, Kashiwa, 277-8562, Japan.
authors.forename: Takuma
authors.initials: T
authors.lastname: Suematsu
authors.forename: Aya
authors.initials: A
authors.lastname: Sato
authors.forename: Masayuki
authors.initials: M
authors.lastname: Sakurai
authors.forename: Kimitsuna
authors.initials: K
authors.lastname: Watanabe
authors.forename: Takashi
authors.initials: T
authors.lastname: Ohtsuki
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D001665:Binding Sites; D017173:Caenorhabditis elegans / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D029742:Caenorhabditis elegans Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D024101:Mitochondrial Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D008969:Molecular Sequence Data; D009154:Mutation; D010444:Peptide Elongation Factor Tu / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D010445:Peptide Elongation Factors / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D011485:Protein Binding; D012346:RNA, Transfer, Amino Acyl / Q000737:chemistry* / Q000378:metabolism
chemical_list: D029742:Caenorhabditis elegans Proteins; D024101:Mitochondrial Proteins; D010445:Peptide Elongation Factors; D012346:RNA, Transfer, Amino Acyl; C503405:tufm-2 protein, C elegans; D010444:Peptide Elongation Factor Tu