Fusions of the lac and trp regions of escherichia coli: covalently fused messenger RNA.

Genetic fusions that help define a transcription termination region in Escherichia coli.

‘IIN trpA gene product was analyzed from a class of strains of Escherichia coli I112 in which the lac operon has been fused by deletion t,o the trp operon. These are strains that have retained the ability to synthesize tryptophan. Two of these strains are shown to make a wild-type trpA product ; these strains retain intact all structural genes of the trp operon. It is proposed that the lac oper...

Fusions of the lac and trp Regions of the Escherichia coli Chromosome.

Two classes of strains were studied in which the lac operon is transposed to a chromosomal site close to the tonB and trp loci. The two classes differ in the orientation of the lac region on the chromosome. In both types of strains, tonB mutants were selected in which deletions removing the tonB locus also caused a fusion of the lac and trp regions. The study of the properties of such fusion st...

Antitermination of transcription from an Escherichia coli ribosomal RNA promoter.

The Escherichia coli lac and ara promoters and rrnC ribosomal RNA promoter-leader region were fused to lacZYA. Transcription termination signals were introduced into the lac genes of these fusions by Tn9 and IS1 insertions. Measurement of lac enzymes from upstream and downstream of the insertions showed that termination signals resulting from these insertions are very efficient when transcripti...

New polarity suppressors in Escherichia coli: suppression and messenger RNA stability.

Two new polarity suppressors (Su27 and Su78) have been isolated in Escherichia coli. Both suppress polarity in the trp and lac operons, and neither shows codon specificity for suppression. Extreme polar mutants of the lac z gene that contain either Su27 or Su78 make mRNA from the entire operon; however, no active beta-galactosidase is translated from the z-gene messenger, and the amount of dist...

Comparison of T7- and Lac-Based Systems for the Periplasmic Expression of Human Granulocyte Macrophage Colony Stimulating Factor in Escherichia coli