Enzymatic activities on cell walls in bacteriophage T 4

Abstract

When isolated particles of bacteriophage T 4 are disrupted by freezing and thawing, they exhibit a lytic activity (particle-bound lysozyme). T 4 e am phage, which has an amber mutation in the structural gene for phage lysozyme, propagated in the restrictive host is devoid of this lytic activity. In addition, a temperature-sensitive mutant in phage lysozyme gene exhibits the particle-bound lytic activity which is also temperature sensitive. It follows from these facts that particle-bound lysozyme and phage lysozyme found free in the lysate are directed by the same structural gene, gene e. The particle-bound lysozyme is not essential to phage infection nor to ‘lysis-from-without’, although these events were postulated to be enzymatic. An enzymatic activity which attacks the cell walls of Escherichia coli and which is different from that of phage lysozyme was found in isolated T 4 phage. It differs from the phage lysozyme in the following respects. (1) The optimum pH of the enzyme lies between 3.5 and 5, while that of the phage lysozyme is around 7. (2) The enzyme lyses neither chloroform-treated cells of Escherichia coli nor intact cells of Micrococcus lysodeikticus. (3) The enzyme is found in T 4 e am phage, which is deficient in the phage lysozyme.