Chemical Sensing: Linking sequence, mechanisms and inhibition

俄克拉荷马州立大学的Smita Mohanty和德克萨斯大学奥斯汀分校的Eric Anslyn获得了化学学部生命过程化学项目的奖励，他们研究了两种鳞翅目昆虫（飞蛾）分子信号的生化和生理机制。他们试图了解在一个物种的交配过程中，气味是如何被雌蛾探测到并传递给雄蛾的分子细节。对诸如气味之类的化学刺激作出反应的能力是所有生物体的基本行为。本项目利用结构和生化实验来发现两种飞蛾的气味交流的基本机制，其中一种是对作物和储存食物的贪婪害虫。计算设计的分子正在合成，并在实验室中进行测试，因为它们有能力竞争性地与气味结合蛋白分子结合，从而抑制雄性对雌性分泌的气味的感知，从而扰乱交配过程。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方面的基本知识差距，并为开发新的、物种特异性的、环境友好的气味模拟物作为有害农药的替代品铺平道路，用于控制昆虫。本科和研究生阶段的学生正在接受最先进仪器的培训，从而为下一代教师、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。鳞翅目昆虫可作为研究FA信号的生化和生理机制的模型。气味/信息素结合蛋白（OBP/PBP）通过围绕气味敏感嗅觉神经元树突的水感淋巴将脂肪酸气味运送到气味受体。脂质通过OBPs/PBPs向嗅觉受体神经元转移的机制细节在很大程度上仍然未知。本项目采用生物化学、生物物理学、分子生物学、化学建模和合成有机化学等综合工具和技术，确定了两种鳞翅目物种（Anthereae polyphemus和Ostrinia furnacalis）中PBPs与脂质结合和释放机制的蛋白质序列中的化学特征。目前的鳞翅目PBP模型，包括Anthereae polyphemus PBP (ApolPBP1)，假设一个ph依赖的构象开关，用于在感觉神经元膜上摄取和释放FA信号。然而，Ostrinia furnacalis PBP （OfurPBP2）的初步数据表明，该蛋白结合脂质并通过一种独特的新机制释放脂质。利用ApolPBP1残基的连续突变策略，系统地将ApolPBP1转化为OfurPBP2模拟物，并利用多学科方法对每个步骤的突变进行表征，以深入了解Ostrinia furnacalis中独特的结构-功能关系和脂质结合和释放的机制。通过基于结构的有机合成，对脂肪酸模拟物进行了自然启发设计，以开发ApoIPBP1的竞争性抑制剂作为模型系统，并建立了一种抑制玉米螟害虫气味的设计策略。这两种关键PBP蛋白的综合互补数据加深了对化学传感不同机制的理解，并为合理设计生态友好型仿生昆虫防治抑制剂提供了基础。教育和推广工作正在利用俄克拉荷马州成功的NSF REU项目来招募和培训本科生技术，积极从HBCUs（历史上的黑人学院和大学）和PUIs（主要的本科院校）招募学生。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。

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.