Structure-function studies on glutamate-1-semialdehyde aminomutase (GSAM)- A key enzyme in chlorophyll biosynthesis

血红素、叶绿素、辅酶F430和类胡萝卜素等辅因子是由8个5-氨基乙酰丙酸分子构成的，5-氨基乙酰丙酸分子构成了所有四吡咯的结构单元。在植物和细菌中，这种化合物由负合作关键酶谷氨酸-1-半醛氨基变位酶（GSAM）合成。该研究计划的主要目标是详细了解GSAM的结构-功能关系和催化机制。目的是获得关于这种酶的机制和化学信息，其目标是（i）研究C5 -和Shemin-途径之间的进化关系，（ii）揭示催化周转期间的亚基间信号传导，以及（iii）设计和分析针对GSAM的特异性抑制剂。由于这种酶在动物中不存在对应物，因此它是安全、选择性除草剂和合理设计此类化合物的一个有希望的靶点。在Stetefeld实验室，将执行综合方法。这些研究涉及结构（X射线晶体学和溶液NMR）、光谱（UV-VIS和Foerster共振电子转移）技术以及功能测定和动力学研究的组合。这些实验将通过分子动力学模拟来补充。这项研究不仅将增强我们对酶催化过程中变构通讯的了解，而且将深入了解基于结构的高选择性除草剂药物设计。了解酶混杂在进化选择过程中的复杂机制，将提供进一步的信息，蛋白质化学与生物技术的相关性。这些结果将有助于在全球范围内设计特异性和靶向抑制剂的基础知识。

Cofactors like heme, chlorophyll, coenzyme F430, and carotinoids are constructed from eight molecules of 5-aminolevulinate, which forms the building block for all tetrapyrrols. In plants and bacteria, this compound is synthesized by the negative cooperative key enzyme glutamate-1-semialdehyde aminomutase (GSAM). The primary goal of the proposed research program is to understand in detail the structure-function relationship and catalytic mechanism of GSAM. The purpose is to obtain mechanistic and chemical information about this enzyme with the goal (i) to investigate the evolutionary relationship between the C5 -and the Shemin-pathways, (ii) to shed light into the inter-subunit signaling during catalytic turnover and (iii) to design and analyze specific inhibitors against GSAM. Because no counterpart of this enzyme exists in animals, it is a promising target for safe, selective herbicides and the rational design of such compounds. In the Stetefeld laboratory, an integrated approach will be performed. These studies involve a combination of structural (X-ray crystallography and solution NMR), spectroscopical (UV-VIS and Foerster Resonance Electron Transfer) techniques together with functional assays and kinetic studies. These experiments will be complemented by Molecular Dynamic simulations. Not only will the research enhance our knowledge of the allosteric communication during enzyme catalysis, but insights will be gained into structure-based drug design of highly selective herbicides. Understanding the complex mechanisms of enzyme promiscuity during evolutionary selection will provide further information about protein chemistry with great biotechnological relevance. The results will contribute to basic knowledge under the global perspective of designing specific and targeted inhibitors.