Asunto(s)
Colifagos/genética , Genes Virales , Proteínas Virales/genética , Bacterias/genética , Bacterias/ultraestructura , Proteínas Bacterianas/análisis , Electroforesis en Gel de Poliacrilamida , Proteínas de la Membrana/análisis , Microscopía Electrónica , Mutación , Transfección , Proteínas Virales/biosíntesis , Replicación ViralRESUMEN
Some spontaneously occurring bacteriophage T4 mutants (far mutants) were able to form plaques in the presence of concentrations of folate analogues that completely inhibit plaque formation by wild-type phage T4. Some of these far mutants were shown to be ribonucleoside diphosphate (RDP) reductase (EC 1.17.4.1) deficient, and some independently isolated RDP reductase-deficient mutants (nrd mutants) were shown to be folate analogue resistant. The map positions of the RDP reductase-deficient far mutants were shown to be within the genes controlling the phage-induced RDP reductase activity.
Asunto(s)
Colifagos/enzimología , Ácido Fólico/análogos & derivados , Ribonucleósido Difosfato Reductasa/metabolismo , Ribonucleótido Reductasas/metabolismo , Mapeo Cromosómico , Colifagos/efectos de los fármacos , Farmacorresistencia Microbiana , Ácido Fólico/farmacología , MutaciónRESUMEN
Two hydroxylamine-induced mutants of bacteriophage T4 defective in modification of host valyl-tRNA synthetase have been isolated by assay of crude extracts for the activity that is characteristic of the wild-type virus. The mutations define a single gene that is situated between the rI and e genes on the T4 genetic map. This new gene is designated vs for valyl-tRNA synthetase. One of the mutations may be of the missense type since it results in the production of a valyl-tRNA synthetase activity that has unusual urea-inactivation properties. The other appears to be an amber mutation since the viral enzyme can only be found after infection of cells that are permissive for amber mutations. No differences in growth properties were found between wild type and amber mutant strains on the nonpermissive host. We conclude that the bacteriophage T4 valyl-tRNA synthetase is not essential for viability under prevailing laboratory conditions.