title: Peptidyl transferase inhibition by the nascent leader peptide of an inducible cat gene.
abstract: The site of ribosome stalling in the leader of cat transcripts is critical to induction of downstream translation. Site-specific stalling requires translation of the first five leader codons and the presence of chloramphenicol, a sequence-independent inhibitor of ribosome elongation. We demonstrate in this report that a synthetic peptide (the 5-mer) corresponding to the N-terminal five codons of the cat-86 leader inhibits peptidyl transferase in vitro. The N-terminal 2-, 3-, and 4-mers and the reverse 5-mer (reverse amino acid sequence of the 5-mer) are virtually without effect on peptidyl transferase. A missense mutation in the cat-86 leader that abolishes induction in vivo corresponds to an amino acid replacement in the 5-mer that completely relieves peptidyl transferase inhibition. In contrast, a missense mutation that does not interfere with in vivo induction corresponds to an amino acid replacement in the 5-mer that does not significantly alter peptidyl transferase inhibition. Our results suggest that peptidyl transferase inhibition by the nascent cat-86 5-mer peptide may be the primary determinant of the site of ribosome stalling in the leader. A model based on this concept can explain the site specificity of ribosome stalling as well as the response of induction to very low levels of the antibiotic inducer.
authors.affiliation: Department of Biological Sciences, University of Maryland Baltimore County, Catonsville 21228.
authors.forename: Z
authors.initials: Z
authors.lastname: Gu
authors.forename: E J
authors.initials: EJ
authors.lastname: Rogers
authors.forename: P S
authors.initials: PS
authors.lastname: Lovett
mesh_terms: D000595:Amino Acid Sequence; D001412:Bacillus subtilis / Q000201:enzymology / Q000235:genetics; D001483:Base Sequence; D002701:Chloramphenicol / Q000494:pharmacology; D015500:Chloramphenicol O-Acetyltransferase / Q000235:genetics / Q000378:metabolism*; D004352:Drug Resistance, Microbial / Q000235:genetics; D004790:Enzyme Induction; D004917:Erythromycin / Q000494:pharmacology; D007700:Kinetics; D008034:Lincomycin / Q000494:pharmacology; D008969:Molecular Sequence Data; D010458:Peptidyl Transferases / Q000037:antagonists & inhibitors* / Q000187:drug effects; D021382:Protein Sorting Signals / Q000235:genetics / Q000378:metabolism*; D012329:RNA, Bacterial; D012270:Ribosomes / Q000378:metabolism
chemical_list: D021382:Protein Sorting Signals; D012329:RNA, Bacterial; D004917:Erythromycin; D002701:Chloramphenicol; D008034:Lincomycin; D015500:Chloramphenicol O-Acetyltransferase; D010458:Peptidyl Transferases