Phenotypic Stability of trp Operon Recombinant Plasmids in Escherichia coli

Phenotypic expression of recombinant plasmids pKT107 and pHK11 in an avirulent avian Escherichia coli.

An avirulent wild-type avian Escherichia coli strain (Av) was electrotransformed with plasmids coding for complement resistance (pKT107) and Colicin V (ColV) production (pHK11) in order to study the effects of complement resistance and ColV production on virulence. Transformants were also compared with the wild type for embryo lethality, uptake by macrophages, motility, growth rate, plasmid con...

Regulation of trp operon in E . coli

Replacement of the Escherichia coli trp operon attenuation control codons alters operon expression.

To test features of the current model of transcription attenuation in amino acid biosynthetic operons, alterations were introduced into the trp operon leader region and expression of the mutated operons was examined in miaA and miaA+ Escherichia coli strains that lacked the trp repressor. The miaA mutation prevents modification of the adenosine residue immediately 3' of the anticodon of tRNAs t...

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...

Polarity in segments of the Escherichia coli trp operon with deleted intraoperonic translational initiation signals.

The effect of deletion of the operator-distal genes of the trp operon, including the trpE-trpD intercistronic punctuation point, on the degree of transcriptional polarity (in this case the effect of a nonsense mutation on the level of mRNA from the distal part of the very gene where the mutation is located) was investigated. Double mutants which contain a nonsense mutation and a deletion in trp...