title: Analysis of coliphage lambda mutations that affect Q gene activity: puq, byp, and nin5.
abstract: We describe in this paper the isolation and characterization of a class of mutations, designated puq, that allow phage lambda to grow better under conditions that limit the synthesis of the phage Q gene product. These mutations were located between phage genes P and Q, a region of the lambda chromosome containing two gene N-independent mutations, nin5 and byp, that we also show to be puq mutations. Whereas the puq-3 and puq-16 mutations probably map under the nin5 deletion, the byp mutation maps between this deletion and the Q lambda-Q phi 80 crossover point. These mutations likely act by increasing the synthesis of the Q gene product. We demonstrate that the clear-plaque phenotype and reduced lysogenization frequency of byp mutants depend on increased Q gene activity. The significance of these results in understanding how transcription proceeds through the P-Q region of the lambda genome is discussed.
mesh_terms: D010582:Bacteriophage lambda / Q000235:genetics* / Q000254:growth & development; D001435:Bacteriophages / Q000201:enzymology; D002874:Chromosome Mapping; D003433:Crosses, Genetic; D005814:Genes, Viral; D008242:Lysogeny; D009113:Muramidase / Q000096:biosynthesis; D009154:Mutation; D014158:Transcription, Genetic; D014764:Viral Proteins / Q000235:genetics*
chemical_list: D014764:Viral Proteins; D009113:Muramidase