Structural and Molecular Mechanism of CdpR Involved in Quorum-Sensing and Bacterial Virulence in Pseudomonas aeruginosa.
Structural and Molecular Mechanism of CdpR Involved in Quorum-Sensing and Bacterial Virulence in Pseudomonas aeruginosa.
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DOI：
10.1371/journal.pbio.1002449
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发表时间：
2016-04
期刊：
影响因子：
9.8
通讯作者：
Liang H
中科院分区：
文献类型：
--
作者：
Zhao J;Yu X;Zhu M;Kang H;Ma J;Wu M;Gan J;Deng X;Liang H
虽然群体感应（QS）系统是重要的调节器的毒力基因表达的机会人类病原体铜绿假单胞菌，其详细的调控机制尚未得到充分的表征。在这里，我们表明，PA 2588的缺失导致绿脓菌素和生物膜的产生增加，以及在小鼠模型中的致病性增强。为了深入了解PA 2588的功能，我们进行了ChIP-seq分析，并确定了PA 2588的28个靶标，包括PA 2588和pqsH之间的基因间区域，该区域编码假单胞菌喹诺酮信号（PQS）的关键合酶。虽然C-末端结构域与其他AraC家族成员的DNA结合区域相似，但结构研究表明，PA 2588在N-末端区域（NTR）具有新的折叠，并且其C-末端HTH（helix-turn-helix）结构域在DNA识别中也是独特的。我们还证明，衔接蛋白ClpS，ATP依赖性蛋白酶ClpAP的一个重要的调节器，直接与PA 2588相互作用之前，提供CdpR ClpAP降解。我们将PA 2588命名为CdpR（ClpAP-降解和致病性调节剂）。此外，clpP或clpS/clpA的缺失促进急性肺炎感染的小鼠模型中的细菌存活。综上所述，本研究揭示CdpR是一个重要的QS调节因子，可与ClpAS-P系统相互作用，调控毒力因子的表达和致病性。新型转录调节因子CdpR抑制铜绿假单胞菌毒力因子的表达和致病性，并被ClpAS-P蛋白酶系统降解。虽然许多转录调控因子调节铜绿假单胞菌毒力因子的表达和分泌，但其潜在的调控网络的分子机制仍然是难以捉摸的。群体感应，细菌的通信和检测细胞密度的能力，以确定最有利的时间来安排集体事件，是已知的管理铜绿假单胞菌毒力。在这项研究中，我们提出了一种新的AraC家族转录因子，CdpR（PA 2588），通过直接调节群体感应假单胞菌喹诺酮信号（PQS）系统控制许多毒力因子。我们解决了CdpR的晶体结构，这表明它的N-末端结构域包含一个独特的折叠，这是不同于其他AraC家族蛋白。此外，我们发现CdpR受ClpAS-ClpP蛋白酶的调节。CdpR与衔接蛋白ClpS相互作用，然后被ATP依赖性ClpAP蛋白酶降解。这是作为铜绿假单胞菌中ClpAS-ClpP蛋白酶底物的群体感应调节剂的第一个实例。这些发现大大扩展了我们对群体感应和毒力调节的理解，并为病原菌中蛋白酶的功能提供了见解。
Although quorum-sensing (QS) systems are important regulators of virulence gene expression in the opportunistic human pathogen Pseudomonas aeruginosa, their detailed regulatory mechanisms have not been fully characterized. Here, we show that deletion of PA2588 resulted in increased production of pyocyanin and biofilm, as well as enhanced pathogenicity in a mouse model. To gain insights into the function of PA2588, we performed a ChIP-seq assay and identified 28 targets of PA2588, including the intergenic region between PA2588 and pqsH, which encodes the key synthase of Pseudomonas quinolone signal (PQS). Though the C-terminal domain was similar to DNA-binding regions of other AraC family members, structural studies revealed that PA2588 has a novel fold at the N-terminal region (NTR), and its C-terminal HTH (helix-turn-helix) domain is also unique in DNA recognition. We also demonstrated that the adaptor protein ClpS, an essential regulator of ATP-dependent protease ClpAP, directly interacted with PA2588 before delivering CdpR to ClpAP for degradation. We named PA2588 as CdpR (ClpAP-degradation and pathogenicity Regulator). Moreover, deletion of clpP or clpS/clpA promotes bacterial survival in a mouse model of acute pneumonia infection. Taken together, this study uncovered that CdpR is an important QS regulator, which can interact with the ClpAS-P system to regulate the expression of virulence factors and pathogenicity. The novel transcriptional regulator CdpR suppresses the expression of virulence factors and pathogenicity in Pseudomonas aeruginosa and is degraded by the ClpAS-P protease system. Although many transcriptional regulators tune P. aeruginosa virulence factor expression and secretion, the molecular mechanisms of the underlying regulatory network are still elusive. Quorum sensing, the ability of bacteria to communicate and detect cell density to determine the most advantageous time to orchestrate collective events, is known to govern P. aeruginosa virulence. In this study, we present a novel AraC-family transcription factor, CdpR (PA2588), that controls numerous virulence factors via directly regulating the quorum sensing Pseudomonas quinolone signal (PQS) system. We solved the crystal structure of CdpR, which showed that its N-terminal domain contains a unique fold that is different from other AraC-family proteins. In addition, we found that CdpR is regulated by the ClpAS-ClpP protease. CdpR interacts with the adaptor protein ClpS and then is degraded by the ATP-dependent ClpAP protease. This is the first example of a quorum-sensing regulator as a substrate of the ClpAS-ClpP protease in P. aeruginosa. These findings significantly extend our understandings of quorum sensing and virulence regulation and provide insights into the function of proteases in pathogenic bacteria.