The modification and targeting of complex metal-cofactors into their apo-enzymes

细菌中钼辅因子（Moco）的生物合成包括5 - GTP初始形成前体Z，将其转化为钼钼苷（MPT），将钼插入到钼钼苷（Mo-MPT）中，并通过附着不同的核苷进一步修饰Mo-MPT，形成双钼钼苷二核苷酸辅因子（bi - mgd）或钼钼苷胞嘧啶二核苷酸辅因子（MCD）。Mo-MPT或MCD可以通过在催化钼位点上添加末端硫化物配体来进一步改性。在合成moco变体后，特定形式必须针对相应的载脂蛋白酶。主要目的是分析Moco插入靶酶的特异性，并确定参与该反应的蛋白质成分，例如Moco结合伴侣。此外，决定Mo- MPT是否被修饰为bi - mgd或MCD的因素尚不清楚。我们将使用两种不同的模型系统来研究Moco在细胞中的修饰和靶向性：一种是定义明确的大肠杆菌系统，它含有结合Mo-MPT、铋- mgd或硫化MCD的酶；另一种是更简单的荚膜红杆菌系统，它只含有两种形式的Moco：硫化Mo-MPT和铋- mgd。主要目的是了解Moco在细菌中的成熟和特定分布所涉及的特定化合物的调节和相互作用。

The biosynthesis of the molybdenum cofactor (Moco) in bacteria involves the initial formation of Precursor Z from 5 GTP, its conversion to molybdopterin (MPT), insertion of molybdenum into MPT (Mo-MPT), and further modification of Mo-MPT by the attachment of different nucleofides either forming the bis-molybdopterin dinucleotide cofactor (bis-MGD) or the molybdopterin cytosine dinucleotide cofactor (MCD). Mo-MPT or MCD can be further modified by the addition of a terminal sulfido ligand to the catalytic molybdenum site. After the synthesis of the Moco-variants, the specific form has to be targeted to the respective apo-enzyme. The main goal is to analyze the specificity of Moco insertion into target enzymes and to specify the protein components, e.g. Mocobinding chaperones, involved in this reacfion. In addition, the factors that determine whether Mo- MPT is modified to bis-MGD or MCD are only poorly understood. We will use two different model systems to study the modificafion and targeting of Moco in the cell: the well defined Escherichia coli system, containing enzymes that either bind Mo-MPT, bis-MGD or sulfurated MCD, and the simpler Rhodobacter capsulatus system, which contains only two forms of Moco: sulfurated Mo- MPT and bis-MGD. The main goal is to understand the regulafion and interplay of the specific compounds involved in the maturafion and specific distribution of Moco in bacteria.