Identification of the products of bacteriophage P22 genes, including a new late gene

Abstract

We report the identification of the products of several bacteriophage P22 genes by SDS-polyacrylamide gel electrophoresis. The products of P22 early genes int, erf, 17, 18, 12, and 23 are identified by their presence in radioactively labeled lysates of cells infected with P22 wild-type phage and absence in lysates of cells infected with phages carrying amber mutations in these genes. The products of the two P22 late genes essential for host cell lysis, genes 13 and 19, are also identified using amber mutants. We also report the isolation and characterization of amber mutants defining a previously unknown P22 late gene, gene 14, and identify the protein product of this new gene. P22 gene 14 amber mutants, like coliphage T4 gene 40 nonsense mutants, have the unusual property that they display a conditional-lethal phenotype only at high temperature. The apparent molecular weights of these and previously identified P22 gene products have been determined. The products of all known essential P22 genes, with the exception of gene 24, have now been identified by SDS-polyacrylamide gel electrophoresis.