GENOMIC ENZYMOLOGY: OMP DECARBOXYLASE SUPRAFAMILY

描述（由申请人提供）：我们想了解（β / α）8桶折叠中功能多样性的结构起源，这是酶中最常见的折叠。我们已经鉴定了一组同源的（β / α）8桶折叠酶，它们在不同的代谢途径中催化与不相关的底物和机制的反应。奥罗替丁5'-磷酸脱羧酶（OMPDC）是这个“超家族”中最具特征的成员。我们建议确定OMPDC超家族其他成员的结构/功能关系，以便我们能够了解使用同源支架催化不相关反应的结构策略。这些研究大大扩展了功能多样性的范围，超出了那些在机械上多样化的酶超家族中发现的范围，例如烯醇化酶和巴豆酶超家族，在这些超家族中，同源酶催化具有共同部分反应的不同反应。四个具体目标整合了机械和结构研究：机械研究将在伊利诺伊州的Gerlt博士实验室进行；结构研究将在威斯康辛州Rayment博士的实验室（co - pi .）进行。

DESCRIPTION (provided by applicant): We want to understand the structural origins of functional diversity in the (beta/alpha)8 barrel fold, the most commonly observed fold in enzymes. We have identified a group of homologous (beta/alpha)8-barrel fold enzymes that catalyze reactions with unrelated substrates and mechanisms in different metabolic pathways. Orotidine 5'-phosphate decarboxylase (OMPDC) is the best characterized member of this "suprafamily." We propose to determine structure/function relationships for other members of the OMPDC suprafamily so that we can understand the structural strategies for using a homologous scaffold to catalyze unrelated reactions. These studies significantly expand the scope of functional diversity beyond those found in mechanistically diverse enzyme superfamilies, e.g., the enolase and crotonase superfamilies, in which homologous enzymes catalyze different reactions that share a common partial reaction. The four Specific Aims integrate mechanistic and structural studies: the mechanistic studies will be performed in Dr. Gerlt's laboratory at Illinois (P.I.); the structural studies will be performed in Dr. Rayment's laboratory at Wisconsin (Co-P.I.): 1) Structure/function relationships will be established for 3-keto-L-gulonate 6-phosphate decarboxylase that catalyzes Mg2+-dependent decarboxylation of beta-ketoacids via an enediolate intermediate. 2) Structure/function relationships will be established for D-arabino-hex-3-ulose 6-phosphate synthase that catalyzes Mg2+-dependent aldol condensation via an enediolate intermediate. 3) Structure/function relationships will be established for D-ribulose 5-phosphate 3-epimerase that catalyzes divalent metal-independent 1,1-proton transfer via an enediolate intermediate. 4) A structural blueprint for functional diversity in the ((beta/alpha)8-barrel fold will be tested.