STRUCTURE OF THE PHI80D3 ILV+SU+7 TRANSDUCING PHAGE AND THE ORIGIN OF ITS SU+7 TRANSFER RNA GENE CONTAINING FRAGMENT

The Bam HI, XhoI, and EcoRI sites of the transducing phage φ{symbol}80d3Su+ 7ilv+ are located. The 1.2×106 MD EcoRI fragment which, when cloned, contains tRNAAsp and expresses the mutant tRNATry gene, Su+7, and which also relaxes control of stable RNA synthesis is found immediately adjacent to the rrnC region. Its tRNA genes, tRNAAsp and tRNATry, are transcribed in the same direction as the ribosomal RNA genes, though no mature rRNA sequences are on the fragment. This fragment also exists as such in another F-prime factor derived from the same Hfr host, and therefore presumably also in the Hfr chromosome itself. It is composed of about half ordinary chromosomal and half F DNA sequences, the latter from the γ-δ region of F. The advantages of a novel mapping method used are discussed. © 1979 Springer-Verlag.