Comparison of lactose uptake in resting and energized Escherichia coli cells: high rates of respiration inactivate the lac carrier.

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...

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

Preparation, characterization, and properties of monoclonal antibodies against the lac carrier protein from Escherichia coli.

Monoclonal antibodies directed against the lac carrier protein purified from the membrane of Escherichia coli were prepared by somatic cell fusion of mouse myeloma cells with splenocytes from an immunized mouse. Several clones produce antibodies that react with the purified protein as demonstrated by solid-phase radioimmunoassay and by immunoblotting experiments; culture supernatants from the c...

Nonadaptive mutations occur on the F' episome during adaptive mutation conditions in Escherichia coli.

One of the most studied examples of adaptive mutation is a strain of Escherichia coli, FC40, that cannot utilize lactose (Lac-) but that readily reverts to lactose utilization (Lac+) when lactose is its sole carbon source. Adaptive reversion to Lac+ occurs at a high rate when the Lac- allele is on an F' episome and conjugal functions are expressed. It was previously shown that nonselected mutat...

Population dynamics of a Lac- strain of Escherichia coli during selection for lactose utilization.

During selection for lactose utilization, Lac+ revertants of FC40, a Lac- strain of Escherichia coli, appear at a high rate. Yet, no Lac+ revertants appear in the absence of lactose, or in its presence if the cells have another, unfulfilled requirement for growth. This study investigates more fully the population dynamics of FC40 when incubated in the absence of a carbon source or when undergoi...