Atomic structures and reaction mechanisms of proteins involved in transfer and insertion of molybdenum cofactor and heme

该项目是一个协作项目，与Forschergruppe中的其他四个项目相互作用。目的是对以下蛋白质进行结晶并解析其原子结构，以解释其迄今为止未知的反应机制：(1)拟南芥中携带钼辅助因子（Moco）的ABA3硫酶单独存在，并与其靶酶黄嘌呤脱氢酶和/或醛氧化酶配合使用。在这里，我们想要揭示ABA3实现黄嘌呤脱氢酶和醛氧化酶所需的Moco插入和mo中心硫化的机制。(2)拟南芥moco供体蛋白Cnx1与其底物MPT-AMP的复合物。结构引导诱变将为MPT-AMP水解提供深入的见解，并将阐明Cnx1 Moco供体平台如何呈现Moco的机制。(3)大肠杆菌中血红素结合蛋白HemW。由于[4Fe-4S]簇和含s -腺苷蛋氨酸的蛋白质在血红素结合并随后转移电子后发生二聚化，因此所涉及的结构变化和可能的催化原理令人感兴趣。(4)血红素d1插入蛋白NirN与血红素d1及其靶蛋白NirS形成复合物。在这里，我们想分析血红素d1在NirN和NirS中的结合有何不同，以及这两种蛋白质如何相互作用以将血红素d1从NirN转移到NirS。

This project is a collaborative project interacting with four other projects within the Forschergruppe. The aim is to crystallize the following proteins and solve their atomic structures in order to decipher their hitherto unknown reaction mechanisms: (1) The molybdenum cofactor (Moco)-carrying ABA3 sulfurase of Arabidopsis alone and in complex with its target enzyme xanthine dehdrogenase and/or aldehyde oxidase. Here we want to unravel the mechanism by which ABA3 achieves the insertion of Moco and the sulfuration of the Mo-center as required by xanthine dehydrogenase and aldehyde oxidase. (2) The Arabidopsis thaliana Moco-donor protein Cnx1 in complex with its substrate MPT-AMP. Structure-guided mutagenesis will provide insight into MPT-AMP hydrolysis and will shed light onto the mechanism how Moco is presented by the Cnx1 Moco-donor platform. (3) The heme-binding protein HemW from Escherichia coli with and without bound heme. Since the [4Fe-4S] cluster and S-adenoslymethionine containing protein is dimerizing upon heme binding and subsequently transferring electrons, involved structural changes and possible catalytic principle are of interest. (4) The heme d1 insertion protein NirN in complex with heme d1 and in complex with its target protein NirS. Here we want to analyze how heme d1 binding in NirN differs from that in NirS and how the two proteins interact with each other for heme d1 transfer from NirN to NirS.