Tetracycline repressor

Figure 7-15 shows the time evolution of the temperature, total energy, and potential energy for a 300 ps simulation of the tetracycline repressor dimer in its induced (i.e., hgand-bound) form. Starting from the X-ray structure of the monomer in a complex with one molecule of tetracycline and a magnesium ion (protein database... 

Figure 7-16. Superimpasition of the X-ray structure of the tetracycline repressor class D dimer (dark, protein database entry 2TRT) with the calculated geometrical average of a 3 ns MD simulation (light trace). Only the protein backbone C trace Is shown, The secondary structure elements and the tertiary structure are almost perfectly reproduced and maintained throughout the whole production phase of the calculation,...

Vaysse L, Harbottle R, Bigger B, et al. Development of a self-assembling nuclear targeting vector system based on the tetracycline repressor protein. J Biol Chem 2004 279(7) 5555-5564. 

Unlike the Gre/loxP system, the tetR/O switch is not dependent on enzyme-based DNA rearrangements but is controlled by the small synthetic compound doxycycline (Dox). In the absence of Dox the tetracycline repressor (tetR), expressed from a constitutive promoter, binds to the tet operator (tetO) within a modified HI promoter and blocks shRNA transcription (Fig. 3b). Exposure to Dox dissociates the tetR from tetO which enables shRNA expression from the HI promoter (22). Thus, gene silencing is induced by Dox addition (20, 22, 23). This system is successfully in use to validate the potential of candidate drug targets in vivo (24-28). A commercial service for the production of Dox inducible knockdown mice and rats is available from Taconic (see www. taconic.com). 

Yao F, Svensjo T, Winkler T et al (1998) Tetracycline repressor, tetR, rather than the tetR-mammalian cell transcription factor fusion derivatives, regulates inducible gene expression in mammalian cells. Himi Gene Ther 9 1939-1950... 

Fig. 5.3. Schematic representation of die display vector pASKIntlOO. fl, fl replication origin cat, chloramphenicol resistance marker tetR, tetracycline repressor encoding gene tetP/O, tetracycline promotor/operator region colEl, ColEl replication origin intimin, truncated eaeA gene of EHEC 0157 H7. Unique Ava I (Sma I, Xma I) and Bam HI restriction sites allow die in-frame fusion of genes encoding various passenger domains, as described in furdier detail in Wentzel et al. [7].

Ettner, N. Hillen, W. Ellestad, G.A. Enhanced Site-Specific Cleavage of the Tetracycline Repressor by Tetracycline Complexed with Iron, J. Am. Chem. Soc. 115, 2546-2548 (1993). 

P = constitutive promoter, tetR = TETrepressor gene,TETR = TET repressor protein, tetO = TET operator sequence, = tetracycline, ere/CRE = Cre recombinase gene/protein, PLEA = late embryogenesis abundant promoter, RIP = gene for ribosome inactivating protein, shaded blocks are loxP sites in orientation shown by solid triangle. After [48]... 

Gene encoding a repressor protein, which regulates the tetracycline efflux system genes Trimethoprim... 

Fig. 1. Molecular mechanism of the tetracycline-regulated shRNA transcription, (a) In the absence of doxycycline, the constitutively expressed repressor homodimerizes and then binds to Tet operator 2 (TetO ) sequences in the inducible expression vector preventing shRNA transcription, (b) When tetracycline is added to the medium, it causes a conformational change in the repressor, leading to its detachment from the Tet operator sequences and shRNA transcription induction.

Takahashi, M., Altschmied, L. and Hillen, W. (1986) Kinetic and equilibrium characterization of the Tet repressor-tetracycline complex by fluorescence measurements. Evidence for divalent metal ion requirement and energy transfer. J. Mol. Biol., 187, 341-348. 

Crystal structures of repressors suggest a common helix-turn-helix motif for DNA binding. Repressors are protein molecules which bind to and block specific nucleotide sequences in DNA (operators), thereby regulating gene expression. Some of the repressors act without co-factors, others need a co-repressor to bind to DNA, like the tryptophan (trp) repressor, or they do not bind to the DNA operator in presence of a co-repressor like tetracyclin (TET) repressor. 

Several prokaryotic repressors can also be used in eukaryotes. Most notable is the tetracycline (TET) inducible expression system, which has had a... 

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