CAREER: Structural and Mechanistic Studies on a Iron-Sulfur Cluster-Based Nitric Oxide Sensor

由于铁（Fe）和硫(S)离子都是高活性的，含有多铁和硫组装（Fe-S簇）的蛋白质在细菌如何感知和快速适应环境压力方面可以发挥多种作用。Fe-S簇蛋白的功能对细菌的适应性是必需的。这些蛋白质通常赋予对其宿主致病的细菌持久性和抗生素抗性。尽管这些Fe-S簇蛋白很重要，但由于处理这些氧敏感蛋白的技术挑战，关于它们在细菌中的功能及其潜在作用机制的知识存在重大空白。生命过程化学和刺激竞争性研究的既定计划（EPSCoR）计划共同资助了内布拉斯加大学林肯分校的张丽梅博士。张教授建立了一个综合的研究和教育项目，其目标是破解放线菌中一种非常重要但尚未得到充分研究的Fe-S簇蛋白WhiB1的独特作用模式的结构基础。从这个项目中获得的知识可能有助于对抗致病性放线菌，如致命的、持久的病原体结核分枝杆菌。这项研究还可以利用放线菌改善生物活性分子的生产，从而对农业有好处。这项研究被整合到一系列旨在招募和培训下一代STEM研究人员的教育和推广活动中，重点是在科学领域代表性不足的群体。它还通过吸引包括K-12、本科生、研究生以及普通公众在内的受众来促进科学素养。WhiB1是一种基于[4Fe-4S]簇的一氧化氮（NO）传感器，广泛分布于放线菌中，对结核分枝杆菌（Mtb）至关重要。WhiB1与Mtb的NO胁迫反应和休眠启动有关。尽管对该蛋白进行了数十年的研究，但在定义WhiB1的作用模式方面仍然存在关键的知识空白，因为它在支持活跃细胞生长和在有氧条件下选择性地感知和调节细胞NO水平的基因表达方面发挥了重要作用。除了一氧化氮感知和应激反应的细节外，WhiB1还代表了一个未被充分研究的参与信号传导的单体转录因子家族，其潜在的作用机制尚不清楚。在这个项目中，张博士和她的研究小组正在使用Mtb WhiB1作为模型蛋白和一套高端结构，光谱和分子工具来推进对[4Fe-4S]簇依赖性蛋白质折叠和动力学控制的机制理解；[4Fe-4S]簇基转录因子的no选择性；以及whib1样单体转录因子的作用方式。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Because iron (Fe) and sulfur (S) ions are both highly reactive, proteins that contain multi-iron and sulfur assemblies (Fe-S clusters), can play versatile roles in how bacteria sense and rapidly adapt to environmental stress. Proper function of Fe-S cluster proteins is required for the fitness of bacteria. These proteins often confer persistence and antibiotic resistance to bacteria that are pathogenic to their host. Despite the importance of these Fe-S cluster proteins, there are critical gaps in knowledge about how they function in bacteria and their underlying mechanisms of action due to the technical challenges of working with these oxygen-sensitive proteins. The Chemistry of Life Processes and Established Program to Stimulate Competitive Research (EPSCoR) Programs jointly fund Dr. Limei Zhang at the University of Nebraska-Lincoln. Professor Zhang builds an integrated research and education program whose goal is to decipher the structural basis for the unique mode of action of a very important, but understudied, Fe-S cluster protein in Actinobacteria called WhiB1. The knowledge gained from this project may help combat pathogenic actinobacteria such as the deadly, persistent pathogen Mycobacterium tuberculosis. The research may also improve production of bioactive molecules using actinobacteria that could, in turn, have benefits for the agriculture. This research is integrated into a series of education and outreach activities designed to recruit and train next-generation STEM researchers, with an emphasis on groups underrepresented in science. It also promotes science literacy by engaging with audiences that include K-12, undergraduate, and graduate students, as well as the general public. WhiB1 is a [4Fe-4S] cluster-based nitric oxide (NO) sensor widely distributed in actinobacteria and essential in Mycobacterium tuberculosis (Mtb). WhiB1 is linked to the NO stress response and initiation of dormancy in Mtb. Despite decades of investigation on this protein, crucial knowledge gaps remain in defining the mode of action of WhiB1 for its essential role in supporting active cell growth and for selectively sensing and regulating gene expression in response to cellular NO levels under aerobic conditions. Beyond the details about NO sensing and stress response, WhiB1 represents a large family of understudied monomeric transcription factors involved in signaling, of which the underlying mechanisms of action are unknown. In this project, Dr. Zhang and her research group are using Mtb WhiB1 as the model protein and a suite of high-end structural, spectroscopic, and molecular tools to advance mechanistic understanding of the [4Fe-4S] cluster-dependent control of protein folding and dynamics; the NO-selectivity of the [4Fe-4S] cluster-based transcription factors; and the mode of action of the WhiB1-like monomeric transcription factors.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.