title: Features of ribosome-peptidyl-tRNA interactions essential for tryptophan induction of tna operon expression.
abstract: Certain nascent peptide sequences, when within the ribosomal exit tunnel, can inhibit translation termination and/or peptide elongation. The 24 residue leader peptidyl-tRNA of the tna operon of E. coli, TnaC-tRNA(Pro), in the presence of excess tryptophan, resists cleavage at the tnaC stop codon. TnaC residue Trp12 is crucial for this inhibition. The approximate location of Trp12 in the exit tunnel was determined by crosslinking Lys11 of TnaC-tRNA(Pro) to nucleotide A750 of 23S rRNA. Methylation of nucleotide A788 of 23S rRNA was reduced by the presence of Trp12 in TnaC-tRNA(Pro), implying A788 displacement. Inserting an adenylate at position 751, or introducing the change U2609C in 23S rRNA or the change K90H or K90W in ribosomal protein L22, virtually eliminated tryptophan induction. These modified and mutated regions are mostly located near the putative site occupied by Trp12 of TnaC-tRNA(Pro). These findings identify features of the ribosomal exit tunnel essential for tna operon induction.
authors.affiliation: Department of Biological Sciences, Stanford University, Stanford, California 94305, USA.
authors.forename: Luis Rogelio
authors.initials: LR
authors.lastname: Cruz-Vera
authors.forename: Soumitra
authors.initials: S
authors.lastname: Rajagopal
authors.forename: Catherine
authors.initials: C
authors.lastname: Squires
authors.forename: Charles
authors.initials: C
authors.lastname: Yanofsky
mesh_terms: D019921:Biotinylation; D003432:Cross-Linking Reagents / Q000737:chemistry; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D029968:Escherichia coli Proteins / Q000032:analysis / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D015870:Gene Expression / Q000235:genetics; D015964:Gene Expression Regulation, Bacterial / Q000235:genetics*; D005838:Genotype; D007763:Lac Operon / Q000235:genetics; D046911:Macromolecular Substances / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism; D008958:Models, Molecular; D009154:Mutation / Q000235:genetics; D009876:Operon / Q000235:genetics*; D010454:Peptide Termination Factors / Q000032:analysis / Q000378:metabolism; D019920:Photoaffinity Labels / Q000737:chemistry; D010957:Plasmids / Q000235:genetics; D014176:Protein Biosynthesis / Q000235:genetics; D012333:RNA, Messenger / Q000378:metabolism; D012338:RNA, Ribosomal, 23S / Q000737:chemistry / Q000235:genetics; D012346:RNA, Transfer, Amino Acyl / Q000235:genetics / Q000378:metabolism*; D012361:RNA, Transfer, Pro / Q000235:genetics; D016601:RNA-Binding Proteins / Q000235:genetics; D012269:Ribosomal Proteins / Q000235:genetics; D012270:Ribosomes / Q000378:metabolism*; D014364:Tryptophan / Q000235:genetics / Q000378:metabolism*; D014368:Tryptophanase / Q000235:genetics*; D014529:Uridine / Q000378:metabolism
chemical_list: D003432:Cross-Linking Reagents; D029968:Escherichia coli Proteins; D046911:Macromolecular Substances; D010454:Peptide Termination Factors; D019920:Photoaffinity Labels; D012333:RNA, Messenger; D012338:RNA, Ribosomal, 23S; D012346:RNA, Transfer, Amino Acyl; D012361:RNA, Transfer, Pro; D016601:RNA-Binding Proteins; D012269:Ribosomal Proteins; C489006:prfB protein, E coli; C056368:ribosomal protein L4; C489371:rplV protein, E coli; C019037:tRNA, peptidyl-; C081473:tnaC protein, E coli; D014364:Tryptophan; D014368:Tryptophanase; D014529:Uridine