title: Mutants of Escherichia coli initiator tRNA that suppress amber codons in Saccharomyces cerevisiae and are aminoacylated with tyrosine by yeast extracts.
abstract: We recently described mutants of Escherichia coli initiator tRNA that suppress amber termination codons (UAG) in E. coli. These mutants have changes in the anticodon sequence (CAU----CUA) that allow them to read the amber codon and changes in the acceptor stem that allow them to bind to the ribosomal aminoacyl (A) site. We show here that a subset of these mutants suppress amber codons in Saccharomyces cerevisiae and that they are aminoacylated with tyrosine by yeast extracts. Analysis of a number of mutants as substrates for yeast tyrosyl-tRNA synthetase has led to identification of the C1.G72 base pair and the discriminator base A73, conserved in all eukaryotic cytoplasmic and archaebacterial tyrosine tRNAs, as being important for recognition. Our results suggest that the C1.G72 base pair and the discriminator base, in addition to the anticodon nucleotides previously identified [Bare, L.A. & Uhlenbeck, O.C. (1986) Biochemistry 25, 5825-5830] as important in yeast tyrosyl-tRNA synthetase recognition, may comprise the critical identity determinants in yeast tyrosine tRNA.
authors.affiliation: Department of Biology, Massachusetts Institute of Technology, Cambridge 02139.
authors.forename: C P
authors.initials: CP
authors.lastname: Lee
authors.forename: U L
authors.initials: UL
authors.lastname: RajBhandary
mesh_terms: D000604:Amino Acyl-tRNA Synthetases / Q000378:metabolism; D001483:Base Sequence; D003001:Cloning, Molecular; D003062:Codon / Q000235:genetics*; D004926:Escherichia coli / Q000235:genetics*; D005798:Genes, Bacterial; D007700:Kinetics; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D009690:Nucleic Acid Conformation; D011401:Promoter Regions, Genetic; D012320:RNA Polymerase III / Q000235:genetics; D012343:RNA, Transfer / Q000235:genetics* / Q000378:metabolism; D012346:RNA, Transfer, Amino Acyl / Q000235:genetics; D012358:RNA, Transfer, Met; D012365:RNA, Transfer, Tyr / Q000235:genetics; D012441:Saccharomyces cerevisiae / Q000235:genetics*; D013489:Suppression, Genetic; D013728:Terminator Regions, Genetic
chemical_list: D003062:Codon; D012346:RNA, Transfer, Amino Acyl; D012358:RNA, Transfer, Met; D012365:RNA, Transfer, Tyr; C024988:tRNA, formylmethionine-; D012343:RNA, Transfer; D012320:RNA Polymerase III; D000604:Amino Acyl-tRNA Synthetases