PROCESS OF INFECTION WITH BACTERIOPHAGE PHIX174 .27. SYNTHESIS OF A VIRAL-SPECIFIC CHLORAMPHENICOL-RESISTANT PROTEIN IN PHIX174-INFECTED CELLS

Cistron VI of φX174 codes for a chloramphenicol-resistant protein that is required for the synthesis of progeny replicative form. The gene product of cistron VI has been isolated by CaHPO4 chromatography using a double label technique in the presence of 30 μg of CM‡ ‡ Abbreviations used: CM, chloramphenicol; RF, replicative form./ml. (Levine & Sinsheimer, 1968a). This technique has been used to demonstrate that the kinetics of synthesis of cistron VI protein are similar to the kinetics of synthesis of progeny RF DNA. The molar quantities of this protein made in 30 μg of CM/ml. are approximately equal to the molar amounts of progeny RF made under these same conditions. Mutants in the six other known cistrons of φX174 synthesize about the same quantities of cistron VI protein as does wild-type φX in 30 μg of CM/ml. A study of the intracellular distribution of cistron VI protein demonstrated that this CM-resistant protein is first found associated with a rapidly sedimenting cellular component (along with the parental RF) and at later times is found in the more slowly sedimenting soluble protein fraction. In Rep- cells, which do not synthesize progeny RF, cistron VI protein is synthesized and is found associated only with the rapidly sedimenting fraction. © 1969.