Quorum Sensing Regulation of EHEC Virulence Genes

项目摘要/摘要 成功地在胃肠道(GI)、肠道中定居 病原体必须感知和响应几个微生物区系和宿主衍生的信号，才能正确地 调节它们的毒力谱系的表达。胃肠道内的一个重要信号是 宿主神经递质去甲肾上腺素(NE)和/或肾上腺素(Epi)，它们具有重要的 在肠道生理学中的作用。还有一个重要的关系是， 神经递质和微生物区系，因为它调节脑内活性EPI和NE的水平 肠腔。宿主将Epi/NE与葡萄糖醛酸结合以使其失活。微生物区系 编码葡萄糖醛酸苷酶(由uidA基因编码)，使葡萄糖醛酸解结合于Epi/NE， 增加管腔内游离生物活性EPi/NE水平。我们确认了前两个 细菌肾上腺素能受体、QSec和QseE。肠道病原菌肠出血性E. Coli(EHEC)，利用肾上腺素能信号通过QSec和QseE仔细调节 表达其毒力基因，以促进肠道的最佳定植。重要的是，EHEC 毒力基因调控与感知葡萄糖醛酸的能力相交， 微生物区系在另一个水平上将Epi/NE脱葡萄糖醛酸化为Epi/NE感觉 王国发出信号。我们发现，葡聚糖酸盐的传感器ExuR是一种重要的 EHEC毒力基因的表达。通过QSec和QseE对Epi/NE的感知与 通过ExuR检测葡萄糖醛酸，确保通过以下方式精确控制毒力基因的表达 EHEC。事实上，轮状柠檬酸杆菌(广泛用作小鼠EHEC的替代模型) 感染)qsec、qseE和exuR突变体对小鼠感染的影响减弱，突显出 该信号系统在EHEC发病机制中的重要作用。另一个神经递质系统， 内源性大麻素系统也与肠道微生物区系交织在一起。内源性大麻素 2-花生四烯基甘油(2-AG)通过QSEC被感测，从而阻止QSEC功能，以及 EHEC和轮状芽胞杆菌毒力基因表达的降低。此外，Epi和2-AG 在QSec感知水平上相互对抗。2AG水平从小到大呈下降趋势 肠至结肠，与EPi/NE水平相反。鉴于EHEC殖民了 结肠，肾上腺素能系统和内源性大麻素系统之间的相互作用，可能有一个关键 在胃肠道内这种病原体的生物地理学中的作用。因此，《公约》的具体目标 这项建议是：具体目标1：研究肾上腺素能与 葡萄糖醛酸信号在肠出血性大肠杆菌发病机制中的作用。具体目标2：调查 内源性大麻素系统在EHEC发病机制中的作用 。

Project Summary/Abstract To successfully colonize and establish themselves in the gastrointestinal (GI) tract, enteric pathogens must sense and respond to several microbiota and host derived signals to properly regulate expression of their virulence repertoire. An important signal within the GI tract is the host neurotransmitter norepinephrine (NE) and/or epinephrine (Epi), which have important functions in intestinal physiology. There is also an important relationship between neurotransmitters and the microbiota, because it modulates the levels of active Epi and NE in the gut lumen. The host conjugates Epi/NE to glucuronate to inactivate it. The microbiota encodes glucuronidases (encoded by the uidA gene) that deconjugate glucuronate from Epi/NE, increasing the levels of free biologically active Epi/NE in the lumen. We identified the first two bacterial adrenergic receptors, QseC and QseE. The enteric pathogen enterohemorrhagic E. coli (EHEC), exploits adrenergic signaling through QseC and QseE to carefully regulate expression of its virulence genes to promote optimal colonization of the gut. Importantly, EHEC virulence gene regulation intersects with the ability to sense glucuronate, linking deglucuronidation of Epi/NE by the microbiota to Epi/NE sensing at another level of inter- kingdom signaling. We identified ExuR, the sensor for glucoronate, as an important regulator of EHEC virulence gene expression. The linking of Epi/NE sensing through QseC and QseE, with glucuronate sensing through ExuR, ensures the precise control of virulence gene expression by EHEC. Indeed, Citrobacter rodentium (extensively used as a surrogate EHEC model for murine infections) qseC, qseE and exuR mutants are attenuated for murine infection, highlighting the important role of this signaling system in EHEC pathogenesis. Another neurotransmitter system, the endocannabinoid system is also intertwined with the gut microbiota. The endocannabinoid 2-Arachidonoylglycerol (2-AG) is sensed through QseC, preventing QseC function, and decreasing expression of virulence genes in EHEC and C. rodentium. Moreover, Epi and 2-AG antagonize each other at the level of QseC sensing. The levels of 2AG decrease from the small intestine to the colon, oppositely from the levels of Epi/NE. Given that EHEC colonizes the colon, the interplay between the adrenergic and endocannabinoid systems, likely has a key function in the biogeography of this pathogen within the GI tract. Accordingly the specific aims of this proposal are: Specific Aim 1: Investigate the relationship among the adrenergic and glucuronate signals in EHEC pathogenesis. Specific Aim 2: Investigate the role of the endocannabinoid system in EHEC pathogenesis. .