Exploring the Dynamics of Prolyl-tRNA Synthetases: Towards Developing a Screening Method for Species-Specific Inhibitors

一般来说，我们的研究小组研究酶动力学和 催化作用本补充建议书旨在获得等温滴定量热仪， 这将有助于研究分子拥挤对酶结构动力学的影响， 功能协调发展的细胞内部非常拥挤，这可能会影响蛋白质 例如结构、折叠、稳定性、配体结合和酶催化的性质。拥挤 影响可以通过硬/空间/熵和/或软/化学/热力学相互作用来介导。我们 目的是调查拥挤/禁闭的确切机制及其对 底物结合和催化。我们正在研究多结构域脯氨酰-tRNA合成酶 ProRS在所有生物体的蛋白质合成中起着至关重要的作用。此前我们 证明了域动态是ProRS功能的核心，ProRS功能受到 crowder诱导的构象整体变化。目前，“制服”的影响 拥挤环境”（非蛋白质拥挤者）和“结构化拥挤环境” （基于蛋白质的crowders）对大肠杆菌（Ec）ProRS构象动力学和功能的影响 正在被探测拥挤效应和限制效应的机械含义是重要的 因为这些酶是有希望的抗微生物药物靶标。构象变化和 通过荧光光谱、分子生物学和分子生物学的方法， 动力学模拟和小分子对接研究，同时改变尺寸，形状， 化学性质和人群的浓度。我们正在研究分子的作用 在基板上使用饱和转移差结合拥挤-核磁 共振，这需要大量的蛋白质和动力学参数， 使用放射性标记底物的酶动力学测定。等温滴定量热法（ITC） 方法是在结合事件期间释放或吸收的热量的无标记直接测量 在相互作用的分子和酶催化反应之间，需要更少的样品。国贸中心 实验提供了热力学概况，这将使我们能够建立 拥挤和限制导致酶功能改变的分子机制。一 详细了解拥挤效应对EC等多结构域蛋白质性质的影响 ProRS可以为蛋白质设计和药物发现开辟新的可能性。而且 ITC设备将使我们能够为生物化学和生物化学专业的学生提供实践经验， 生物物理化学课程（约25名学生/学期）通过设计课程嵌入式研究 量热法的项目，并教他们在药物发现的配体结合热力学。

Broadly speaking, our research group studies the interplay between enzyme dynamics and catalysis. This supplemental proposal is developed to acquire Isothermal Titration Calorimeter, which will aid in investigating the effects of molecular crowding on enzyme structure-dynamics- functions. The interior of a cell is extremely crowded, which can potentially impact protein properties such as structure, folding, stability, ligand binding, and enzyme catalysis. The crowding effects could mediate through hard/steric/entropic and/or soft/chemical/enthalpic interactions. Our objective is to investigate the exact mechanism of crowding/confinement and their impacts on substrate binding and catalysis. We are studying the multidomain prolyl-tRNA synthetases (ProRSs), which play a vital role in protein synthesis in all living organisms. Earlier, we demonstrated that domain dynamics is central to ProRSs functions, which are impacted by the crowder-induced shift in the conformational ensemble. Currently, the impact of the “uniform crowding environment” (nonprotein-based crowders) and “structured crowding environment” (protein-based crowders) on conformational dynamics and function of Escherichia coli (Ec) ProRS is being probed. The mechanistic implications of crowding and confinement effects are significant as these enzymes are promising anti-microbial drug targets. The conformational change and crowder-enzyme interactions are being probed by fluorescence spectroscopy, molecular dynamics simulations, and small molecule docking studies, while varying the size, shape, chemical nature, and concentration of the crowders. We are examining the role of molecular crowders on the substrate binding using Saturation Transfer Difference - Nuclear Magnetic Resonance, which requires a large quantity of proteins and kinetics parameters are obtained from enzyme kinetics assays using radiolabeled substrates. The isothermal titration calorimetry (ITC) method is a label-free direct measurement of the heat evolved or absorbed during a binding event between interacting molecules and enzyme-catalyzed reactions and requires less sample. ITC experiments provide the thermodynamic profiles, which would enable us to establish the molecular mechanism of crowding and confinement resulting in enzyme's altered function. A detailed understanding of crowding effects on the properties of multidomain proteins like Ec ProRS could open up new possibilities for protein designing and drug discovery. Moreover, the ITC equipment would enable us to provide hands-on experiences to students in biochemistry and biophysical chemistry courses (~25 students/semester) by designing course-embedded research projects on calorimetry and teaching them the ligand binding thermodynamics in drug discovery.