Purine catabolites as inducers of bacterial gene expression

当细菌病原体感染宿主时，宿主会进行防御，目的是杀死入侵者。然而，细菌会对抗这种防御，经常利用宿主衍生的防御化合物来触发自身新陈代谢的变化，这些变化旨在促进它们在不适宜居住的宿主环境中生存。该项目旨在描述细菌植物病原体检测和利用寄主衍生信号以促进生存和毒力的机制。对感染过程的更全面的了解将导致对经济上重要的植物病原体的生命周期的新的见解，并最终激励控制疾病进展的努力。该计划还提供了一个促进发现的机会，同时为学生创造了一个包容性的培训环境。研究生将是开展这一研究项目不可或缺的一部分，并将鼓励他们寻求职业发展机会。对于本科生来说，他们中的许多人将从机构为少数族裔学生设立的项目中招募，实质性的研究经验不仅与他们必须完成的课程相结合，而且在进入就业市场或寻求进入专业学校时也会提高他们的价值。总体而言，这些培训机会有助于发展一支有竞争力的STEM工作队伍。宿主对病原体的部分反应是产生活性氧物种。嘌呤分解代谢物尿酸盐和黄嘌呤在感染过程中积累，因为负责产生活性氧物种的宿主酶之一是黄嘌呤氧化还原酶，否则它通过将次黄嘌呤转化为黄嘌呤和将黄嘌呤转化为尿酸来参与嘌呤代谢。以前的工作表明，PECS家族转录因子与这些嘌呤分解代谢物结合。这个项目的主要目标是解决存在其他尿酸盐/黄嘌呤反应转录因子的假设。利用编码Pecs家族蛋白MftR的泰兰伯克霍尔德氏菌，将采用免疫沉淀和质谱分析相结合的方法来鉴定其他嘌呤反应转录因子。识别的蛋白质将在体外进行DNA和配体结合分析，体内实验将包括分析编码识别的转录因子基因缺失的菌株的基因表达和表型特征，以及染色质免疫沉淀以识别直接靶标。将考察MftR重新布线这些调节电路的能力。通过专注于对相同信号做出反应的几种蛋白质，目标是实现受嘌呤分解代谢影响的基因调控网络的更完整的图景。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

When a bacterial pathogen infects a host, the host mounts a defense, which is intended to kill the invader. The bacteria, however, counter such defenses, often harnessing the very host-derived defense compounds to trigger changes in their own metabolism, changes that are designed to promote their survival in the inhospitable host environment. This project aims to delineate mechanisms by which bacterial plant pathogens detect and exploit host-derived signals to promote survival and virulence. A more complete understanding of the infection process will lead to novel insights into the lifecycle of economically important plant pathogens and ultimately inspire efforts to control disease progression. This program also offers an opportunity for advancing discovery while creating an inclusive training environment for students. Graduate students will be integral to developing this research project, and they will be encouraged to pursue career-building opportunities. For undergraduate students, many of whom will be recruited from institutionally established programs for minority students, a substantive research experience not only integrates with their required coursework, but it also enhances their value when entering the job market or seeking admission to professional schools. Overall, these training opportunities contribute to the development of a competitive STEM workforce.Part of the host response to pathogens is the production of reactive oxygen species. The purine catabolites urate and xanthine accumulate during infection because one of the host enzymes responsible for production of reactive oxygen species is xanthine oxidoreductase, which otherwise participates in purine metabolism by converting hypoxanthine to xanthine and xanthine to urate. Previous work has shown that PecS family transcription factors bind these purine catabolites. The primary objective of this project is to address the hypothesis that other urate/xanthine-responsive transcription factors exist. Using Burkholderia thailandensis, which encodes the PecS-family protein MftR, a combination of immunoprecipitation and mass spectrometry will be implemented to identify additional purine-responsive transcription factors. Identified proteins will be analyzed in vitro in terms of DNA and ligand binding, and in vivo experiments will include analyses of gene expression and phenotypes characteristic of strains deleted for genes encoding the identified transcription factor as well as chromatin immunoprecipitation to identify direct targets. The ability of MftR to rewire these regulatory circuits will be examined. By focusing on several proteins that respond to the same signals, the objective is to achieve a more integrated picture of the gene regulatory networks affected by purine catabolites.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.