The effect of chloramphenicol on synthesis of ΦX 174-specific proteins and detection of the cistron A protein

Abstract

Synthesis of ΦX 174-specific proteins in Escherichia coli H 502 was examined on sodium dodecyl sulphate-acrylamide gels by coelectrophoresis of proteins from [3H]leucine-labelled infected cells and [14C]leucine-labelled reference cells, which had been infected with ultraviolet-light irradiated phage. Addition of 35 μg/ml of chloramphenicol during infection reduced the synthesis of ΦX-specific proteins of cistrons A, F, H and D to different degrees. The greatest reduction is found in synthesis of the cistron F product (coat protein), while synthesis of cistron D protein (single-strand DNA synthesis) is relatively resistant to the drug. Mutants in cistron A, which are unable to replicate RF, show a great reduction in the synthesis of all ΦX-specific proteins upon infection in the presence of chloramphenicol which made the identification of the cistron A protein unfeasible under these conditions.

In the absence of chloramphenicol the cistron A product was identified as a protein with a molecular weight of 55 000. The cistron A protein is always strongly associated with the cell membrane.