Specialized Transducing Phages for Ribos

Specialized lambda transducing phages have been isolated carrying approximately half the ribo- somal protein genes of E. coli. These phages carry regions of the bacterial chromosome between aroE and fus. The ribosomal protein genes on these phages have been iden- tified by the stimulation of ribosomal protein synthesis in ultraviolet-irradiated bacteria following infection by the transducing phage, and by the in vitro synthesis of ribo- somal proteins in a DNA-dependent protein synthesizing system. The results indicate Xdspcl probably carries at least 22 ribosomal protein genes and Xdspc2 at least 26 genes. All these genes are clustered between trkA and strA. At least 13 of them have not been previously mapped. Many of the genes for the ribosomal proteins (r-proteins) of Escherichia coli are clustered near the strA locus (for a review, see ref. 1). Intergeneric crosses have suggested that at least 22 out of approximately 50 r-protein genes are in this region of the chromosome (2-5). At present not all the r-protein genes can be distinguished in intergeneric crosses. Thus, some of the other r-protein genes may also be in this cluster. Only one structural gene has been unambiguously mapped in another region of the chromosome, that is, the gene for the 30S protein