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

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

A bacterial strain is described in which the structural genes of the lac operon have been fused by deletion to the trp operon. It is shown that in this strain lac messenger RNA synthesis is controlled by the t?y regulatory gene. DNA-RNA hybridization studies show that a fraction of the lac messenger RNA is covalently linked to the tr2, messenger RNA. These results demonstrate that at least a fr...

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

CONSTRUCTION OF RECOMBINANT PLASMIDS FOR PERIPLASMIC EXPRESSION OF HUMAN GROWTH HORMONE IN ESCHERICHIA COLI UNDER T7 AND LAC PROMOTERS

In order to study the periplasmic expression of human growth hormone (hGH) in Escherichia coli, the related cDNA was inserted in two expression plasmids carrying pelB signal peptide, one with lac bacterial promoter and the other with a bacteriophage T7-based promoter. The recombinant plasmids were moved to TG1 and BL21 strains of E. coli, respectively. To induce the expression systems, IPTG and...

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...

Indolmycin-mediated inhibition and stimulation of transcription at the trp promoter of Escherichia coli.

Escherichia coli cells harboring a non-attenuated trp-lac operon fusion were used to evaluate the effects of indolmycin on the initiation of transcription at the trp promoter. Indolmycin caused repression in trpR+ strains and in trpR deletion mutants, although higher effector concentrations were required in the latter situation. Plasmid-mediated elevation in tryptophanyl-tRNA synthetase reverse...