Transcription of the lac operon of Escherichia coli.

DNA supercoiling, a critical signal regulating the basal expression of the lac operon in Escherichia coli

Escherichia coli lac repressor (LacI) is a paradigmatic transcriptional factor that controls the expression of lacZYA in the lac operon. This tetrameric protein specifically binds to the O1, O2 and O3 operators of the lac operon and forms a DNA loop to repress transcription from the adjacent lac promoter. In this article, we demonstrate that upon binding to the O1 and O2 operators at their nati...

The inhibition of Escherichia coli lac operon gene expression by antigene oligonucleotides-mathematical modeling.

Gene transcription is regulated by transcription factors that can bind to specific regions on DNA. Antigene oligonucleotides (oligos) can bind to specific regions on DNA and form a triplex with the double-stranded DNA. The triplex can competitively inhibit the binding of transcription factors and, as a result, transcription can be inhibited. A genetically structured model has been developed to ...

Cyclic adenosine monophosphate-independent mutants of the lactose operon of Escherichia coli.

In Escherichia coli the transcription of the lactose operon, like other catabolite-sensitive operons, requires catabolite gene activator protein and 3',5'-cyclic adenosine monophosphate in addition to ribonucleic acid polymerase. We isolated and analyzed lac(+) revertants from a crp(-) strain of E. coli. We found that revertants with a higher level of expression only for the lac operon lie in t...

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...

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

Direct observation of a 91 bp LacI-mediated, negatively supercoiled DNA loop by atomic force microscope.

Escherichia coli lactose repressor (LacI), a tetrameric protein, is a paradigmatic transcriptional factor that controls the expression of lacZYA in the lac operon. It specifically binds to the O1, O2, and O3 operators of the lac promoter, forms DNA loops, and regulates transcription of the lac operon. In this article, utilizing combined techniques of DNA-nicking assay and AFM imaging, we direct...