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

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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.