Expression of ribosomal protein genes cloned in Charon vector phages and identification of their promoters.

We have identified ribosomal protein genes carried by several EroRI DNA fragments which were originally derived from XxpcI or Xfctx2 transducing phages and then cloned into Charon 3 and Charon 4 vector phages (see the preceding paper (Williams, B. G., Blattner, F. It., Jaskunas, S. R., and Nomura, M. (1977) J. Rid. Chem. 252, 7344-7354)). Ultraviolet (LJV)-irradiated E.srheri~hia coli cells were infected with these hybrid phages in the presence of suitable radioactive amino acids, and the radioactive proteins synthesized were identified. Uy comparing proteins synthesized in UVirradiated nonlysogenir tells with those in UV-irradiated lysogrnir cells, it was also possible to determine whether genes on cloned DNA fragments were transcribed from bacterial promoters or phage promoters. From these results (summarized in Fig. l), we conclude that: the genes for S4, Sll, and S13 and a promoter for these genes lie on the 5% fragment; the genes for L15 and L30 are on the 3% fragment, which does not have a harterial promoter; the genes for SlO. L2, L3, L4. and L23 are on the adjacent ‘2.2 and 4.6% fragment,s and a promoter for these genes is on the 2.2% fragment together with the SlO gene; the gene tufA (coding for EF-Tu), but not its bacterial promoter, is on the 8.5% fragment; the genes for S7, S12, and most of the fus gene (coding for the EF-C: factor) together with their bacterial promoter are on the 11% fragment; the gene for L17 is on the 27% fragment without a promoter. The method described in this paper may he a useful general approach for detecting