Transfer RNA structure and coding specificity. II. A D-arm tertiary interaction that restricts coding range.

D Smith; M Yarus

doi:10.1016/0022-2836(89)90497-x

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Transfer RNA structure and coding specificity. II. A D-arm tertiary interaction that restricts coding range.

D Smith·M Yarus

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Abstract

We investigated the structural basis of the kinetic effect on coding specificity by the D-arm mutant (G24 to A) of Escherichia coli tRNATrp. A set of tRNA genes with structural alterations in the D-arm was constructed by site-directed mutagenesis in vitro, and we determined the in vivo translational activities of these tRNAs. Our results suggest that a hydrogen-bond donor in the major groove of the D-helix at position 24 is required for the expansion of tRNA wobble coding specificity. From inspection of tRNA crystal structure, we identified a potential new tertiary pairing of base 24 with the base at position 9 (this base links the acceptor and D-stems). We constructed tRNAs with mutations at position 9 and showed that the phenotypes of position 11-24 D-arm mutants are indeed dependent on the identity of base 9. Our analysis of the effects of these mutations on the interactions of tRNA with the ribosome and with aminoacyl-tRNA synthetase suggests that the conformation or conformational dynamics of the middle of the tRNA molecule alters the kinetics of the interaction with the ribosomal coding site. The 9-23 and putative 9-24 tertiaries, and perhaps other normal tertiary interactions in this region, modulate these kinetics to increase or decrease coding specificity.

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Amino Acyl-tRNA Synthetases Codon Escherichia coli Models, Molecular Molecular Structure Mutation Nucleic Acid Conformation Protein Biosynthesis RNA, Bacterial RNA, Messenger RNA, Ribosomal RNA, Transfer Ribosomes Suppression, Genetic Journal Article Research Support, U.S. Gov't, P.H.S.

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D Smith, M Yarus. 1989-04-05. Transfer RNA structure and coding specificity. II. A D-arm tertiary interaction that restricts coding range.. https://doi.org/10.1016/0022-2836(89)90497-x

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