Anhydrotetracycline (hydrochloride)

Anhydrotetracycline (hydrochloride) (ATC) is a powerful effector for the tetracycline repressor (TetR) and reverse tetracycline repressor (revTetR) systems [1].

Tetracycline repressor (TetR) is an effector-regulated DNA-binding protein that binds tightly to its palindromic tetO operator DNA in the absence of effector, thereby blocking the transcription of any downstream genes. Binding of tetracycline (TC) or anhydrote-tracycline (ATC) to TetR causes the repressor to dissociate from the DNA and gene transcription can occur. Contrary to TetR, reverse tetracycline repressor (revTetR) mutant binds tetO only in the presence of ATC [2][3].

Anhydrotetracycline (hydrochloride) is a powerful effector for TetR and revTetR systems. Anhydrotetracycline (ATC) bound TetR with a 500-fold higher affinity and represented the most efficient inducer [2]. ATC bound the Tet repressor 35-fold more potent than Tet [4]. However, ATC acted as a corepressor in revTetR variant. In β-galactosidase (β-gal) assays, TetR inhibitedβ-gal expression to nearly 1%, while ~100% expression was accomplished in the presence of 0.4 μM ATC. RevTetR produced almost 100%β-gal activity in the absence of ATC, while the presence of 0.4 μM ATC resulted in a 5-fold decrease ofβ-gal activity [2].

References:
[1].? Gossen M, Bujard H. Anhydrotetracycline, a novel effector for tetracycline controlled gene expression systems in eukaryotic cells. Nucleic Acids Res. 1993 Sep 11;21(18):4411-2.
[2].? Kamionka A, Bogdanska-Urbaniak J, Scholz O, et al. Two mutations in the tetracycline repressor change the inducer anhydrotetracycline to a corepressor. Nucleic Acids Res. 2004 Feb 4;32(2):842-7.
[3].? Resch M, Striegl H, Henssler EM, et al. A protein functional leap: how a single mutation reverses the function of the transcription regulator TetR. Nucleic Acids Res. 2008 Aug;36(13):4390-401.
[4].? Degenkolb J, Takahashi M, Ellestad GA, et al. Structural requirements of tetracycline-Tet repressor interaction: determination of equilibrium binding constants for tetracycline analogs with the Tet repressor. Antimicrob Agents Chemother. 1991 Aug;35(8):1591-5.

无水四环素（盐酸盐）(ATC) 是四环素阻遏物 (TetR) 和反向四环素阻遏物 (revTetR) 系统的强大效应物 [1]。

四环素阻遏物 (TetR) 是一种效应子调节的 DNA 结合蛋白，在没有效应子的情况下与其回文 tetO 操纵子 DNA 紧密结合，从而阻断任何下游基因的转录。四环素 (TC) 或无水四环素 (ATC) 与 TetR 的结合会导致阻遏物与 DNA 解离，从而发生基因转录。与 TetR 相反，反向四环素阻遏物 (revTetR) 突变体仅在存在 ATC 的情况下结合 tetO [2][3]。

Anhydrotetracycline（盐酸盐）是 TetR 和 revTetR 系统的强大效应物。无水四环素 (ATC) 以高 500 倍的亲和力结合 TetR，是最有效的诱导剂 [2]。 ATC 结合 Tet 阻遏物的效力是 Tet 的 35 倍 [4]。然而，ATC 在 revTetR 变体中充当辅阻遏物。在 β-半乳糖苷酶 (β-gal) 测定中，TetR 将 β-gal 表达抑制到近 1%，而在 0.4 μM ATC 存在的情况下实现了约 100% 的表达。在没有 ATC 的情况下，RevTetR 产生几乎 100% 的β-gal 活性，而存在 0.4 μM ATC 时，β-gal 活性降低了 5 倍 [2]。