Transcriptional autoregulation by Mycobacterium tuberculosis PhoP involves recognition of novel direct repeat sequences in the regulatory region of the promoter
Transcriptional autoregulation by Mycobacterium tuberculosis PhoP involves recognition of novel direct repeat sequences in the regulatory region of the promoter
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DOI：
10.1016/j.febslet.2006.09.004
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发表时间：
2006-10-02
期刊：
影响因子：
3.5
通讯作者：
Sarkar, Dibyendu
中科院分区：
文献类型：
--
作者：
Gupta, Sankalp;Sinha, Akesh;Sarkar, Dibyendu
PhoP-PhoR 双组分系统对于人和小鼠巨噬细胞或小鼠体内结核分枝杆菌 (MTB) 的毒力和细胞内生长至关重要。在这里，PhoP 和截短的 PhoR 传感器蛋白被证明利用双组分信号系统特有的保守残基参与磷酸转移反应。源自 phoP 启动子-lacZ 构建体的 β-半乳糖苷酶活性在 PhoP 存在时受到抑制，表明反应调节剂存在转录自动抑制作用。 PhoP 的体外结合与体内转录抑制一致，表明在 PhoP 浓度升高时，转录起始复合物的组装不依赖于磷酸化。 DNaseI 保护研究揭示了 phoP 启动子内的共有识别序列，其中包括三个 9 bp 的同向重复单元。每个重复单元都会调整到共识 (1)AC(T)/(T)(G)/(T)(G)/(G)P(y)AP(u)C(9)。新鉴定的同向重复单元序列的改变减轻了 PhoP 存在下的 phoP 转录抑制，表明 PhoP 通过与重复单元的序列特异性相互作用来抑制其自身的表达。总之，这些结果确定了 phoP 启动子调控区域中迄今为止未知的 PhoP 调控的遗传决定因素，这对于理解 PhoP 如何作为 MTB 的全局调控因子发挥作用至关重要。 (c) 2006 年欧洲生化学会联合会。由 Elsevier B.V. 出版。保留所有权利。
The PhoP-PhoR two-component system is essential for virulence and intracellular growth of Mycobacterium tuberculosis (MTB) in human and mouse macrophages or in mice. Here, PhoP and truncated PhoR sensor proteins were shown to participate in phosphotransfer reactions using conserved residues characteristic of two-component signaling systems. beta-Galactosidase activity originating from phoP promoter-lacZ construct was inhibited in presence of PhoP, suggesting transcriptional auto-inhibition by the response regulator. In vitro binding of PhoP is consistent with the in vivo transcriptional repression, indicating phosphorylation-independent assembly of the transcription initiation complex at elevated concentrations of PhoP. DNaseI protection studies reveal a consensus recognition sequence within the phoP promoter that includes three 9-bp direct repeat units. Each repeat unit adjusts to the consensus (1)AC(T)/(T)(G)/(T)(G)/(G)P(y)AP(u)C(9). Alteration in the sequence of the newly-identified direct repeat units relieved phoP transcriptional repression in presence of PhoP, suggesting that PhoP represses its own expression by sequence-specific interaction(s) with the repeat units. Together, these results identify so far unknown PhoP-regulated genetic determinants in the regulatory region of the phoP promoter that are central to understanding of how PhoP may possibly function as a global regulator in MTB. (c) 2006 Federation of European Biochemical Societies. Published by Elsevier B.V. All rights reserved.