title: Involvement of the nusB gene products in transcription of Escherichia coli tryptophan operon in vitro.
abstract: Synthesis of trp mRNA in vitro directed by plasmid DNA carrying the entire trp operon was studied using crude protein extracts (S-100) from Escherichia coli strains carrying the nusA or nusB mutation or both. It was found that the levels of trp mRNA transcribed from the promoter-distal genes (trpCBA) relative to that from the promoter-proximal genes (trpED) was markedly lower with extracts from the nus- mutants than that from the nus+ strain. Kinetic experiments suggest that termination of RNA transcripts at intragenic transcriptional barriers is prevented by the nus gene products from allowing efficient expression of the operon.
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics*; D004926:Escherichia coli / Q000235:genetics; D005798:Genes, Bacterial; D007700:Kinetics; D009876:Operon; D010957:Plasmids; D012333:RNA, Messenger / Q000096:biosynthesis; D014158:Transcription, Genetic; D014364:Tryptophan / Q000235:genetics*
chemical_list: D001426:Bacterial Proteins; D012333:RNA, Messenger; D014364:Tryptophan