A transducing lambda phage carrying grpE, a bacterial gene necessary for lambda DNA replication, and two ribosomal protein genes, rpsP (S16) and rplS (L19).

A grpE mutation of Escherichia coli K12, which blocks DNA replication of the phage lambda (Saito and Uchida, 1977), was mapped at 56 min on the standard genetic map. A transducing lambda phage, lambdagrpE22, carrying the wild type allele of the grpE gene was constructed in vitro. Structures of lambdagrpE22 and its viable deletion derivatives were determined by electron microscopic analyses of appropriate heteroduplexes. Proteins coded by the bacterial DNA incorporated into the transducing phages were detected by two-dimensional gel electrophoresis. The results showed that the product of the grpE gene is a weakly acidic protein of molecular weight 24,000. Structural genes for two ribosomal proteins, rplS (L19) and rpsP (S16) were also shown to be carried by lambdagrpE22.