title: A nascent peptide is required for ribosomal bypass of the coding gap in bacteriophage T4 gene 60.
abstract: Bacteriophage T4 DNA topoisomerase gene 60 contains a 50 nucleotide untranslated region within the coding sequence of its mRNA. Translational bypass of this sequence by elongating ribosomes has been postulated for the mode of synthesis of an 18 kd polypeptide specified by the split coding segments. Ribosome bypass of the untranslated region also occurs when a segment of gene 60 is fused to lacZ and expressed in E. coli. The efficiency of bypass in these gene 60-lacZ fusions approaches 100%. Here, mutations that delete, insert, or substitute nucleotides from gene 60-lacZ fusions are examined. Essential features necessary for high level gap bypass emerging from this analysis are a cis-acting nascent peptide sequence, a short duplication bordering the gap, and a stop codon contained in a stem-loop structure at the 5' junction of the gap.
authors.affiliation: Howard Hughes Medical Institute, University of Utah, Salt Lake City, Utah.
authors.forename: R B
authors.initials: RB
authors.lastname: Weiss
authors.forename: W M
authors.initials: WM
authors.lastname: Huang
authors.forename: D M
authors.initials: DM
authors.lastname: Dunn
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D002872:Chromosome Deletion; D003001:Cloning, Molecular; D003062:Codon / Q000235:genetics; D004250:DNA Topoisomerases, Type II / Q000235:genetics*; D004251:DNA Transposable Elements; D004926:Escherichia coli / Q000235:genetics*; D005814:Genes, Viral; D008957:Models, Genetic; D008969:Molecular Sequence Data; D009690:Nucleic Acid Conformation; D014176:Protein Biosynthesis; D012333:RNA, Messenger / Q000235:genetics; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D012270:Ribosomes / Q000378:metabolism*; D013604:T-Phages / Q000201:enzymology / Q000235:genetics*; D015678:Viral Structural Proteins / Q000235:genetics; D001616:beta-Galactosidase / Q000235:genetics / Q000378:metabolism
chemical_list: D003062:Codon; D004251:DNA Transposable Elements; D012333:RNA, Messenger; D011993:Recombinant Fusion Proteins; D015678:Viral Structural Proteins; D001616:beta-Galactosidase; D004250:DNA Topoisomerases, Type II