Organization and nucleotide sequence of a new ribosomal operon in Escherichia coli containing the genes for ribosomal protein S2 and elongation factor Ts.

We report the nucleotide sequence of the four min region of the Escherichia coli genetic map that includes the genes for ribosomal protein S2 (rpsB) and translation elongation factor EF-Ts (tsf), and the possible location of regulatory sites within this two gene operon. The data indicate that the gene order is: rpsBp-rpsB-tsf-tsft. One potential regulatory site is a 16 nucleotide sequence in the rpsB leader region encompassing the ribosome binding site and the translation initiation codon. This has a high degree of homology with nucleotides 8 through 23 on the 5' end of 165 ribosomal RNA, and might signify a sequence that is necessary for post-transcriptional control of rpsB expression. The data allow one to infer the amino acid sequences of S2 and EF-Ts.

Organization of genes in the four minute region of the Escherichia coli chromosome: evidence that rpsB and tsf are co-transcribed.

Restriction endonuclease-generated DNA fragments of lambda polC-9 (Friesen et al. 1976) have been cloned on plasmid vehicles. Expression of genes carried by these plasmids was determined either by genetic complementation of the appropriate mutants, or in ultraviolet-irradiated cells. On the basis of these experiments we have inferred the following gene order in the four minute region of the Escherichia coli chromosome: tonA-dapD4-dapD2-rpsB-tsf-22 kilodalton protein - fir 27,000-firA-dnaE. We suggest that rpsB and tsf are in one transcriptional unit, with rpsB being promoter-proximal. We also suggest the possible position of the promoter for dnaE.

Expression of Escherichia coli ribosomal protein and RNA polymerase genes cloned on plasmids.

Fragments of lambda drifd 18 DNA with different end-points within the set of structural genes of ribosomal proteins L11 (RPLK), Li (rplA), L10 (rplJ) and L12 (rplL) as well as the beta (rpoB) ANd beta' (rpoC) subunits of RNA polymerase have been cloned on plasmids. These plasmids were transformed in host cells which were mutant for each of the genes, enabling expression of both wild-type (plasmid-borne) and mutant (chromosomal) genes to be differentiated. On the basis of these results we propose the following genetic structure for the region: rplK and rplA are in one operon; rplL, rpoB and rpoC are in a second. Our data suggest the possibility that rplJ is by itself in an operon situated between the other two.

Fine-structure mapping of the rts, rplK, rplL, and rpoB genes of Escherichia coli.

The specialized transducing phage lambdacI857S7drifd18 was used as a donor in a transductional mapping of four genes in the rif region of the Escherichia coli genome. The gene order was rts-2.9-rplL-0.8-rpoB, where the numbers indicate intermarker distances in kilobases. The possible orientation of these genes with respect to each other and to neighboring genes is discussed.

A transducing bacteriophage lambda carrying the structural gene for elongation factor Ts.

A specialized transducing bacteriophage lambdadpolCdap D-9 has been isolated that carries the structural gene for EF-Ts1 (tsf). The presence of EF-Ts among the proteins synthesized under the direction of this phage in UVL-inactivated cells has been detected by two-dimensional gel electrophoresis and has been verified by antibody precipitation. In an induced lysogen of this phage the relative rate of synthesis of EF-Ts is increased 4-fold. Evidence is presented which suggest that the structural genes for ribosomal protein S2 (rpsB) and RNA polymerase sigma factor (sit) also lies on lambdadpolCdap D-9.