Regulation of imm gene expression in bacteriophage T4-infected cells.

Two polypeptides (imm-a and imm-b) which are not induced by an immunity mutant T4Dimm2 but by a wild-type strain T4D were identified by sodium dodecyl sulphate (SDS)-polyacrylamide gel electrophoresis. Their mol. wt. were 77 000 and 45 000, respectively. These polypeptides exhibited a similar kinetic pattern of synthesis. Within a few minutes p.i. the primary phage established the system that inhibited imm gene expression of superinfecting phage. This was shown by measuring both the phenotypic expression of immunity and the synthesis of imm gene polypeptides. The expression of two other immediate-early genes, namely genes s and 30, and early gene 33, was not affected by primary infection.