title: Injection of ultraviolet-damage-specific enzyme by T4 bacteriophage.
abstract: When UV-irradiated T4 bacteriophage (v(+)) infects in the presence of chloramphenicol, the phage DNA rapidly acquires single-stranded breaks proportional to the dose of UV. In contrast, when UV-irradiated T4 v(1) (radiation sensitive mutant) infects under identical conditions, the phage DNA remains integral. A series of coinfections with v(+) and v(1) phage (UV-v(1) + majority non-UV-v(+) and UV-v(+) and majority non-UV-v(1)) show that the enzyme responsible for breakage is injected by the phage. It is also demonstrated that the v(1) phage injects an inactive enzyme that delays breakage by the v(+) enzyme and interferes with subsequent repair. The cross of v(+) and v(1) phage produces mixed progeny that contain both active and inactive enzyme in a single capsid. The possible function of this breaking enzyme, necessitating injection of multiple copies, is considered.
mesh_terms: D001426:Bacterial Proteins / Q000096:biosynthesis; D002499:Centrifugation, Density Gradient; D002701:Chloramphenicol / Q000494:pharmacology; D003090:Coliphages / Q000032:analysis / Q000201:enzymology* / Q000254:growth & development / Q000528:radiation effects; D003433:Crosses, Genetic; D004267:DNA Viruses / Q000032:analysis / Q000201:enzymology* / Q000254:growth & development / Q000528:radiation effects; D004279:DNA, Viral / Q000032:analysis / Q000528:radiation effects*; D004789:Enzyme Activation; D004798:Enzymes / Q000378:metabolism*; D004926:Escherichia coli / Q000378:metabolism; D007930:Leucine / Q000378:metabolism; D009154:Mutation; D010759:Phosphorus Isotopes; D011830:Radiation Effects; D014316:Tritium; D014466:Ultraviolet Rays
chemical_list: D001426:Bacterial Proteins; D004279:DNA, Viral; D004798:Enzymes; D010759:Phosphorus Isotopes; D014316:Tritium; D002701:Chloramphenicol; D007930:Leucine