title: The Enzymatic Paradox of Yeast Arginyl-tRNA Synthetase: Exclusive Arginine Transfer Controlled by a Flexible Mechanism of tRNA Recognition.
abstract: Identity determinants are essential for the accurate recognition of transfer RNAs by aminoacyl-tRNA synthetases. To date, arginine determinants in the yeast Saccharomyces cerevisiae have been identified exclusively in vitro and only on a limited number of tRNA Arginine isoacceptors. In the current study, we favor a full cellular approach and expand the investigation of arginine determinants to all four tRNA Arg isoacceptors. More precisely, this work scrutinizes the relevance of the tRNA nucleotides at position 20, 35 and 36 in the yeast arginylation reaction. We built 21 mutants by site-directed mutagenesis and tested their functionality in YAL5, a previously engineered yeast knockout deficient for the expression of tRNA Arg CCG. Arginylation levels were also monitored using Northern blot. Our data collected in vivo correlate with previous observations. C35 is the prominent arginine determinant followed by G36 or U36 (G/U36). In addition, although there is no major arginine determinant in the D loop, the recognition of tRNA Arg ICG relies to some extent on the nucleotide at position 20. This work refines the existing model for tRNA Arg recognition. Our observations indicate that yeast Arginyl-tRNA synthetase (yArgRS) relies on distinct mechanisms to aminoacylate the four isoacceptors. Finally, according to our refined model, yArgRS is able to accommodate tRNA Arg scaffolds presenting N34, C/G35 and G/A/U36 anticodons while maintaining specificity. We discuss the mechanistic and potential physiological implications of these findings.
authors: Laboratory of tRNA biology, Department of Biology, College of Charleston, Charleston, South Carolina, United States of America.
authors: Ariel
authors: A
authors: McShane
authors: Laboratory of tRNA biology, Department of Biology, College of Charleston, Charleston, South Carolina, United States of America.
authors: Eveline
authors: E
authors: Hok
authors: Laboratory of tRNA biology, Department of Biology, College of Charleston, Charleston, South Carolina, United States of America.
authors: Jensen
authors: J
authors: Tomberlin
authors: Architecture et Réactivité de l'ARN, Université de Strasbourg, CNRS, Institut de Biologie Moléculaire et Cellulaire, 15 rue René Descartes, 67084, Strasbourg CEDEX, France.
authors: Gilbert
authors: G
authors: Eriani
authors: Laboratory of tRNA biology, Department of Biology, College of Charleston, Charleston, South Carolina, United States of America.
authors: Renaud
authors: R
authors: Geslain
mesh_terms: D000926:Anticodon; D001120:Arginine / Q000378:metabolism; D001126:Arginine-tRNA Ligase / Q000378:metabolism*; D009154:Mutation; D010641:Phenotype; D011485:Protein Binding; D012343:RNA, Transfer / Q000235:genetics / Q000378:metabolism; D012347:RNA, Transfer, Arg / Q000235:genetics / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism*; D013379:Substrate Specificity; D046249:Transfer RNA Aminoacylation
chemical_list: D000926:Anticodon; D012347:RNA, Transfer, Arg; D012343:RNA, Transfer; D001120:Arginine; D001126:Arginine-tRNA Ligase