Mechanistic Investigation on Carrier Protein Recognition in Quorum Signal Synthases

群体信号合成酶中载体蛋白识别的机制研究

• 批准号: 1905311
• 负责人: Rajesh Nagarajan
• 金额: $ 46.69万
• 依托单位: Boise State University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2019
• 资助国家: 美国
• 起止时间: 2019-08-01 至 2023-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1905311&HistoricalAwards=false
• 关键词: Mechanistic; Investigation; Carrier; Protein; Recognition

Bacteria synthesize and release specific chemicals that signal to the local microbial population that it has reached a level sufficient to change their behavior from acting as individual cells to a multicellular mode. The bacterial population is said to reach a quorum level and the signaling chemicals are called Quorum Sensing (QS) signals. When a quorum population is achieved, bacteria turn on cooperative, "group-beneficial" social traits that include biofilm formation (for example plaques on teeth), toxin secretion and development of resistance to antibiotics. The specificity in QS signals made by the enzyme acyl-homoserine lactone (AHL) synthase requires that this protein selectively recognizes and reacts with a specific helper protein (an acylated acyl-carrier protein) to avoid creating non-specific signals. With this award, the Chemistry of Life Processes is funding Dr. Rajesh Nagarajan at Boise State University to investigate the molecular interactions of the carrier protein and AHL synthase that direct the synthesis of correct quorum sensing signals. This project utilizes a combination of biochemistry, enzymology and nuclear magnetic resonance (NMR) tools to determine the molecular details for how two different AHL synthases selectively recognize native over non-native compounds for the acyl-carrier protein. Results from this study help guide the design of quorum sensing specific inhibitors as potential ways to disrupt bacterial growth. The educational plan of this project provides interdisciplinary training in cutting-edge research for high school, undergraduate and graduate students and integrates evidence-based research methods into the laboratory curriculum. The plan for outreach engages low-income, rural and first-generation college students at Boise State University in research, and offers a hands-on, direct research opportunities for high school science teachers in the laboratory. This project helps to connect Dr. Nagarajan's laboratory with local high school science teachers and high school classrooms to encourage students to consider careers in STEM disciplines.Acyl carrier proteins serve as indispensable cofactors in several primary and secondary metabolic pathways that include the biosynthesis of fatty acids, polyketides, quorum sensing signals and nonribosomal peptide natural products. In general, the molecular basis on how acyl carrier proteins are able to interact with a multitude of enzyme partners and yet retain specificity for each enzyme is a poorly understood research area. This project addresses how two different AHL synthases recognize their cognate carrier proteins to impart fidelity in quorum signal synthesis. The methodology used in this study should open new doors for a broader investigation on differences in carrier protein recognition between enzymes involved in primary and secondary metabolism. Finally, small molecules that interrupt intercellular communication could also serve as useful chemical probes to investigate the social communication among bacterial communities. This project is jointly funded by the Chemistry of Life Processes (CLP) program of the Chemistry Division, the Established Program to Stimulate Competitive Research (EPSCoR), and Office of Multidisciplinary Activities (OMA) in the Mathematical and Physical Sciences (MPS) Directorate.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.

细菌合成并释放特定的化学物质，向当地的微生物种群发出信号，表明它已经达到足以将其行为从单个细胞转变为多细胞模式的水平。据说细菌种群达到了法定数量水平，信号化学物质被称为群体感应（QS）信号。当达到法定数量时，细菌会开启合作的“群体有益”社会特征，包括生物膜形成（例如牙齿上的斑块），毒素分泌和对抗生素的耐药性发展。由酰基高丝氨酸内酯（阿勒）合酶产生的QS信号的特异性要求该蛋白质选择性地识别特异性辅助蛋白（酰化酰基载体蛋白）并与其反应，以避免产生非特异性信号。有了这个奖项，生命过程的化学正在资助博伊西州立大学的Rajesh Nagarajan博士研究载体蛋白和阿勒合酶的分子相互作用，指导正确的群体感应信号的合成。该项目利用生物化学，酶学和核磁共振（NMR）工具的组合来确定两种不同的阿勒酶如何选择性地识别酰基载体蛋白的非天然化合物的分子细节。这项研究的结果有助于指导群体感应特异性抑制剂的设计，作为破坏细菌生长的潜在方法。该项目的教育计划为高中生、本科生和研究生提供尖端研究方面的跨学科培训，并将循证研究方法纳入实验室课程。该计划的推广从事低收入，农村和第一代大学生在博伊西州立大学的研究，并提供了一个动手，直接研究的机会，高中科学教师在实验室。该项目有助于将Nagarajan博士的实验室与当地高中科学教师和高中教室联系起来，鼓励学生考虑STEM学科的职业生涯。酰基载体蛋白在几个初级和次级代谢途径中担任不可或缺的辅因子，包括脂肪酸，聚酮化合物，群体感应信号和非核糖体肽天然产物的生物合成。一般来说，酰基载体蛋白如何能够与多种酶伴侣相互作用，但仍保留对每种酶的特异性的分子基础是一个知之甚少的研究领域。本计画探讨两种不同的阿勒酵素如何辨识其同源载体蛋白，以赋予群体信号合成的保真度。在这项研究中使用的方法应该打开新的大门，更广泛的调查载体蛋白质识别的差异，参与初级和次级代谢的酶。最后，阻断细胞间通讯的小分子也可以作为有用的化学探针来研究细菌群落之间的社会通讯。该项目由化学部的生命过程化学（CLP）计划，刺激竞争研究的既定计划（EPSCoR），数学和物理科学多学科活动办公室（OMA）该奖项反映了NSF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进行评估，被认为值得支持的搜索.