Chemical Sensing: Linking sequence, mechanisms and inhibition

俄克拉荷马州州立大学的Smita Mohanty和德克萨斯大学奥斯汀分校的Eric Anslyn获得了化学系生命过程化学项目的一项奖励，以研究两种鳞翅目昆虫（蛾）中分子信号的生化和生理机制。 他们试图了解在交配过程中气味是如何被检测到并从雌蛾传递到雄蛾的分子细节。对气味等化学刺激做出反应的能力是所有生物体的基本行为。该项目利用结构和生物化学实验来发现两种蛾类的气味通信的基本机制，其中一种是作物和储存食物的贪婪害虫。计算机设计的分子正在实验室中合成和测试它们竞争性结合气味结合蛋白分子的能力，以抑制雄性对雌性分泌气味的感知，从而破坏交配过程。 从这项研究中获得的知识有助于弥合动物嗅觉的化学和机械细节知识的根本差距，并为开发新型，物种特异性和环境友好的气味模拟物作为有害农药的替代品铺平道路，用于昆虫控制。本科生和研究生阶段的学生正在接受最先进仪器的培训，从而为未来的教师，研究人员和创新者做好准备。昆虫使用不溶性脂肪酸（FA）衍生物作为高度特异性的信号分子。鳞翅目昆虫是研究FA信号传导的生理生化机制的模型。气味/信息素结合蛋白（OBP/PBP）将脂肪酸气味通过气味敏感嗅觉神经元树突周围的水感淋巴运送到气味受体。OBP/PBP将脂质转移到嗅觉受体神经元的机制的细节在很大程度上仍然未知。该项目使用生物化学，生物物理学，分子生物学，化学建模和合成有机化学的组合工具和技术，以确定蛋白质序列中的化学特征，这些特征决定了两种鳞翅目物种中PBP的脂质结合和释放机制：Anthereaepolyphemus和Ostriniapericacalis。目前的模型鳞翅目PBP，包括Anthereae polyphemus PBP（ApolPBP 1），假定一个pH依赖性的构象开关的吸收和释放的FA信号在感觉神经元膜。然而，Ostriniaperacalis PBP（OfurPBP 2）的初步数据表明，这种蛋白质结合脂质并通过一种独特的新机制释放脂质。 采用ApolPBP 1残基连续突变的策略，系统地将ApolPBP 1转化为OfurPBP 2模拟物，并采用多学科方法对每个步骤的突变体进行表征，以深入了解Ostrinia mostracalis中独特的结构-功能关系以及脂质结合和释放机制。 自然启发的设计脂肪酸模拟物正在通过基于结构的有机合成，开发ApoIPBP 1的竞争性抑制剂作为模型系统，并建立一个设计策略，在Ostrinia pesticalis气味抑制。 这两个关键PBP蛋白的组合，互补数据加深了对化学传感不同机制的理解，并为合理设计用于昆虫控制的生态友好型仿生抑制剂提供了基础。 教育和外展工作正在利用成功的NSF REU计划在俄克拉荷马州招募和培训本科生技术，积极招募来自HBCU（历史上的黑人学院和大学）和PUI（小学本科院校）的学生。该奖项反映了NSF的法定使命，并被认为值得通过使用基金会的智力价值和更广泛的影响审查标准进行评估来支持。

Smita Mohanty of Oklahoma State University and Eric Anslyn of the University of Texas, Austin, are supported by an award from the Chemistry of Life Processes Program in the Division of Chemistry to investigate the biochemical and physiological mechanisms of molecular signaling in two lepidopteran insect species (moths). They seek to understand the molecular detail of how an odor is detected and communicated from the female moth to the male moth within a species during the mating process. The ability to respond to chemical stimuli such as odors is a fundamental behavior of all organisms. This project is utilizing structural and biochemical experiments to discover the basic mechanism of odor communication in two moth species, one of which is a voracious pest of crops and stored foods. Computationally-designed molecules are being synthesized and tested in the laboratory for their ability to competitively bind to odor-binding protein molecules to inhibit the sensing of female-secreted scent by the male, and thus disrupt the mating process. Knowledge gained from this research is helping bridge the fundamental gap in knowledge of the chemical and mechanistic details of sense of smell in animals, as well as paving the way for the development of novel, species-specific, and environmentally-friendly odor mimetics as alternatives to harmful pesticides, for insect control. Students at the undergraduate and graduate levels are being trained in state-of-the-art instrumentation, thus preparing the future generation of teachers, researchers, and innovators.Insects use insoluble fatty acid (FA) derivatives as highly-specific signaling molecules. Lepidopteran insects serve as a model for studying the biochemical and physiological mechanisms of FA signaling. Odor/pheromone binding proteins (OBP/PBP) ferry the fatty acid odor to the odorant receptor across the aqueous sensillar lymph that surrounds the dendrites of odor-sensitive olfactory neurons. The details of the mechanism of lipid transfer to the olfactory receptor neuron by OBPs/PBPs remain largely unknown. This project is using the combined tools and techniques of biochemistry, biophysics, molecular biology, chemical modeling, and synthetic organic chemistry to identify the chemical signatures in the protein sequences that dictate the mechanism of lipid binding and release by PBPs in two lepidopteran species: Anthereae polyphemus and Ostrinia furnacalis. The current model for lepidopteran PBPs, including Anthereae polyphemus PBP (ApolPBP1), posits a pH-dependent conformational switch for the uptake and release of the FA signal at the sensory neuron membrane. However, preliminary data for Ostrinia furnacalis PBP (OfurPBP2) suggests that this protein binds lipid and releases it through a distinct, novel mechanism. A strategy of successive mutations in ApolPBP1 residues is being used to systematically transform ApolPBP1 into an OfurPBP2 mimic, and characterize the mutants at each step using a multidisciplinary approach, to gain insight into the unique structure-function relationship and mechanism of lipid binding and release in Ostrinia furnacalis. Nature-inspired design of fatty-acid mimetics is being performed through structure-based organic synthesis, to develop a competitive inhibitor of ApoIPBP1 as a model system, and establish a design strategy for odor inhibition in the Ostrinia furnicalis pest. This combined, complementary data on two key PBP proteins is deepening the understanding of distinct mechanisms of chemical sensing, and providing a foundation for the rational design of eco-friendly biomimetic inhibitors for insect control. Educational and outreach efforts are leveraging the successful NSF REU program at Oklahoma State to recruit and train undergraduates techniques, with students actively recruited from HBCUs (Historically Black Colleges and Universities) and PUIs (Primarily Undergraduate Institutions).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.