VIABLE T4 BACTERIOPHAGE CONTAINING CYTOSINE- SUBSTITUTED DNA (T4dC PHAGE)

Abstract

A multiple mutant of bacteriophage T4, which contained cytosine-substituted DNA, was grown in a suppressor-containing or non-containing (sup.degree.) strain of E. coli B or K12, and the progeny phage obtained was grown on test strains carrying various restriction systems. The growth of this phage was subject to the rK, rB and rP1 restriction systems. Two T4 strains, named UNF-rl and UNF-r+1, sensitive to the rK, rB and rP1 restriction systems, were newly derived by the genetic cross and mutagenesis. The former had the unf-39 mutation instead of the alc-8 mutation, the latter had the rII+ region and the unf-39 mutation, besides the amE51 (gene 56; dCTPase), denA (endonuclease II) and denB (endonuclease IV) mutations. UNF-r+l DNA possessed a SalI recognition site in the rII-denA region which was deleted in UNF-rl DNA.