title: Synthesis of bacteriophage-coded gene products during infection of Escherichia coli with amber mutants of T3 and T7 defective in gene 1.
abstract: During nonpermissive infection by a T7 amber mutant in gene 1 (phage RNA polymerase-deficient), synthesis of the products of the phage genes 3 (endonuclease), 3, 5 (lysozyme), 5 (DNA polymerase), and 17 (serum blocking power) was shown to occur at about half the rate as during wild-type infection. This relatively high rate of expression of "late" genes (transcribed normally by the phage RNA polymerase) seems to be a general feature of all T7 mutants in gene 1 from our collection. In contrast, T3 gene 1 mutants and a T7 gene 1 mutant from another collection showed late protein synthesis at very reduced rates. Synthesis of the gene 3 endonuclease by T7 gene 1 mutants was very sensitive to the addition of rifampin 2 min after infection, conditions under which there was very little inhibition during wild-type infection. This supports the notion that late gene expression during nonpermissive infection by gene 1 mutants is dependent on the transcription of the T7 genome by the host RNA polymerase. In contrast to T3 gene 1 mutants, the T7 gene 1 mutants of our collection directed the synthesis of phage DNA during nonpermissive infection. This DNA accumulated as a material sedimenting faster than mature T7 DNA.
mesh_terms: D002499:Centrifugation, Density Gradient; D003090:Coliphages / Q000201:enzymology* / Q000254:growth & development / Q000378:metabolism; D003601:Cytotoxicity Tests, Immunologic; D004254:DNA Nucleotidyltransferases / Q000096:biosynthesis*; D004267:DNA Viruses / Q000201:enzymology / Q000254:growth & development / Q000378:metabolism; D004279:DNA, Viral / Q000096:biosynthesis; D012321:DNA-Directed RNA Polymerases / Q000096:biosynthesis*; D003851:Deoxyribonucleases / Q000096:biosynthesis*; D004926:Escherichia coli / Q000201:enzymology* / Q000378:metabolism / Q000528:radiation effects; D005796:Genes; D007106:Immune Sera; D009113:Muramidase / Q000096:biosynthesis*; D009154:Mutation; D011830:Radiation Effects; D012293:Rifampin / Q000494:pharmacology; D014158:Transcription, Genetic; D014316:Tritium; D014466:Ultraviolet Rays; D014764:Viral Proteins / Q000096:biosynthesis
chemical_list: D004279:DNA, Viral; D007106:Immune Sera; D014764:Viral Proteins; D014316:Tritium; D004254:DNA Nucleotidyltransferases; D012321:DNA-Directed RNA Polymerases; D003851:Deoxyribonucleases; D009113:Muramidase; D012293:Rifampin