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Example of a T-REx system controlling the expression of shRNA. Tetracycline-controlled transcriptional activation is a method of inducible gene expression where transcription is reversibly turned on or off in the presence of the antibiotic tetracycline or one of its derivatives (e.g. doxycycline).
To perform a run-off transcription assay, a gene of interest, including the promoter, is cloned into a plasmid. [4] The plasmid is digested at a known restriction enzyme cut site downstream from the transcription start site such that the expected mRNA run-off product would be easily separated by gel electrophoresis. [1] [2] [4]
Activator-binding sites may be located very close to the promoter or numerous base pairs away. [2] [3] If the regulatory sequence is located far away, the DNA will loop over itself (DNA looping) in order for the bound activator to interact with the transcription machinery at the promoter site. [2] [3]
The tac promoter consists of the '–35' region of the trp promoter and the '–10' region of the lac promoter (and differs from a related trc promoter by 1 bp [3]). The tac promoter is, therefore, inducible by IPTG (Isopropyl β- D -1-thiogalactopyranoside), whilst also allowing higher maximum gene expression than either the lac or trp promoters.
It is also commonly called the -10 sequence or element, because it is centered roughly ten base pairs upstream from the site of initiation of transcription. The Pribnow box has a function similar to the TATA box that occurs in promoters in eukaryotes and archaea : it is recognized and bound by a subunit of RNA polymerase during initiation of ...
Promoters are located near the transcription start sites of genes, upstream on the DNA (towards the 5' region of the sense strand). Promoters can be about 100–1000 base pairs long, the sequence of which is highly dependent on the gene and product of transcription, type or class of RNA polymerase recruited to the site, and species of organism ...
Detection methods based on DNA rely on the complementarity of two strands of DNA double helix that hybridize in a sequence-specific manner. The DNA of GMO consists of several elements that govern its functioning. The elements are promoter sequence, structural gene and stop sequence for the gene. [1]
Promoters P1 and P3 are for the beta-lactamase gene. P3 is the natural promoter, and P1 is artificially created by the ligation of two different DNA fragments to create pBR322. P2 is in the same region as P1, but it is on the opposite strand and initiates transcription in the direction of the tetracycline resistance gene.