title: Escherichia coli nusB mutations that suppress nusA1 exhibit lambda N specificity.
abstract: The bacteriophage lambda N protein regulates phage development by selectively suppressing transcription termination in its host, Escherichia coli. The E. coli nus mutants prevent N activity. To provide additional information on transcription termination, we have isolated pseudo-revertants of the nusA1 mutation that restore lambda N function. One series of pseudo-revertants lie in the E. coli nusB gene, whose product is normally required for lambda N activity. These mutations are N-specific: mutations that restore lambda N activity do not restore the activity of the analogous N protein of phage 21. Similarly, nusB mutations that restore phage 21 N function are deficient for lambda N function. Mapping of the two classes of mutation is consistent with their location in two distinct domains in the nusB protein. We discuss whether nusB is specific for N protein or for some other component of this regulation system, e.g. the phage site (nut) required for N action.
mesh_terms: D010582:Bacteriophage lambda / Q000235:genetics*; D002874:Chromosome Mapping; D002876:Chromosomes, Bacterial; D004926:Escherichia coli / Q000235:genetics*; D005686:Galactokinase / Q000235:genetics / Q000378:metabolism; D009154:Mutation; D009876:Operon; D010443:Peptide Chain Termination, Translational; D013489:Suppression, Genetic; D014158:Transcription, Genetic; D014764:Viral Proteins / Q000235:genetics*
chemical_list: D014764:Viral Proteins; D005686:Galactokinase