title: tRNA acceptor-stem and anticodon bases embed separate features of amino acid chemistry.
abstract: The universal genetic code is a translation table by which nucleic acid sequences can be interpreted as polypeptides with a wide range of biological functions. That information is used by aminoacyl-tRNA synthetases to translate the code. Moreover, amino acid properties dictate protein folding. We recently reported that digital correlation techniques could identify patterns in tRNA identity elements that govern recognition by synthetases. Our analysis, and the functionality of truncated synthetases that cannot recognize the tRNA anticodon, support the conclusion that the tRNA acceptor stem houses an independent code for the same 20 amino acids that likely functioned earlier in the emergence of genetics. The acceptor-stem code, related to amino acid size, is distinct from a code in the anticodon that is related to amino acid polarity. Details of the acceptor-stem code suggest that it was useful in preserving key properties of stereochemically-encoded peptides that had developed the capacity to interact catalytically with RNA. The quantitative embedding of the chemical properties of amino acids into tRNA bases has implications for the origins of molecular biology.
authors.affiliation: a Department of Biochemistry and Biophysics , University of North Carolina at Chapel Hill , Chapel Hill , NC 27599-7260.
authors.forename: Charles W
authors.initials: CW
authors.lastname: Carter
authors.affiliation: a Department of Biochemistry and Biophysics , University of North Carolina at Chapel Hill , Chapel Hill , NC 27599-7260.
authors.forename: Richard
authors.initials: R
authors.lastname: Wolfenden
mesh_terms: D000596:Amino Acids / Q000737:chemistry / Q000235:genetics*; D000604:Amino Acyl-tRNA Synthetases / Q000737:chemistry / Q000235:genetics; D000926:Anticodon / Q000737:chemistry / Q000235:genetics*; D001665:Binding Sites; D019143:Evolution, Molecular; D005815:Genetic Code; D009690:Nucleic Acid Conformation; D014176:Protein Biosynthesis; D017510:Protein Folding; D012343:RNA, Transfer / Q000737:chemistry / Q000235:genetics*
chemical_list: D000596:Amino Acids; D000926:Anticodon; D012343:RNA, Transfer; D000604:Amino Acyl-tRNA Synthetases
keywords: Amino acid mimics; multi-stage development of genetic coding; protein folding; tRNA identity elements; translation