Antibiotic binding releases autoinhibition of the TipA multidrug-resistance transcriptional regulator.
Antibiotic binding releases autoinhibition of the TipA multidrug-resistance transcriptional regulator.
复制标题
抗生素结合释放 TipA 多重耐药转录调节因子的自身抑制。
DOI：
10.1074/jbc.ra120.016295
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发表时间：
2020-12-18
期刊：
影响因子：
--
通讯作者：
Li X
中科院分区：
文献类型：
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作者：
Jiang X;Zhang L;Teng M;Li X
细菌耐药性策略的研究可以帮助开发新的抗微生物药物，作为全球细菌抗生素耐药性日益普遍的对策。其中一种策略涉及TipA类转录因子，它们构成了针对不同抗生素的最小自调节多药耐药（MDR）系统。然而，我们没有足够的信息，关于抗生素结合如何诱导转录激活，以设计可能干扰这一过程的分子。为了了解更多，我们确定了来自新月柄杆菌的SkgA的晶体结构作为代表性的TipA蛋白。我们确定了一个意想不到的空间方向和位置的抗生素结合TipAS效应结构域在载脂蛋白状态。我们观察到TipAS结构域的α6-α7区域，其通常负责形成抗生素结合裂缝的盖子以紧密封闭结合的抗生素，参与二聚体界面并通过与apo状态下的DNA结合结构域相互作用而稳定。进一步的结构和生化分析表明，未配体的TipAS结构域在空间上阻碍启动子DNA结合，但在抗生素结合后经历显著的构象转变，通过其α6-α7区域的开关释放这种自抑制。因此，包括tipA和RNA聚合酶在内的MDR基因的启动子可用于转录，从而实现有效的抗生素抗性。这些对TipA蛋白激活的分子机制的见解推进了我们对TipA蛋白以及细菌MDR系统的理解，并可能为阻断细菌耐药性提供重要线索。
Investigations of bacterial resistance strategies can aid in the development of new antimicrobial drugs as a countermeasure to the increasing worldwide prevalence of bacterial antibiotic resistance. One such strategy involves the TipA class of transcription factors, which constitute minimal autoregulated multidrug resistance (MDR) systems against diverse antibiotics. However, we have insufficient information regarding how antibiotic binding induces transcriptional activation to design molecules that could interfere with this process. To learn more, we determined the crystal structure of SkgA from Caulobacter crescentus as a representative TipA protein. We identified an unexpected spatial orientation and location of the antibiotic binding TipAS effector domain in the apo state. We observed that the α6-α7 region of the TipAS domain, which is canonically responsible for forming the lid of antibiotic binding cleft to tightly enclose the bound antibiotic, is involved in the dimeric interface and stabilized via interaction with the DNA-binding domain in the apo state. Further structural and biochemical analyses demonstrated that the unliganded TipAS domain sterically hinders promoter DNA binding, but undergoes a remarkable conformational shift upon antibiotic binding to release this autoinhibition via a switch of its α6-α7 region. Hence, the promoters for MDR genes including tipA and RNA polymerases become available for transcription, enabling efficient antibiotic resistance. These insights into the molecular mechanism of activation of TipA proteins advance our understanding of TipA proteins as well as bacterial MDR systems, and may provide important clues to block bacterial resistance.