Structural Investigation of Enzymes that Utilize Cobalamin and AdoMet Cofactors

描述(申请人提供)：在过去的几十年里，从植物、动物或微生物中提取的天然产品或化合物极大地促进了药物的发现和开发。由于自然界的化合物比现有的人造药物更复杂，结构上也更独特，了解自然界用于设计这些分子的化学是基于天然产品的药物发现的一个重要里程碑。许多医学上重要的天然产物生物合成途径利用酶的化学，这些酶曾被认为是S-腺苷蛋氨酸(ADOMet)自由基超家族的一小部分。今天，这个亚群，依赖钴胺的ADOMet自由基酶类包含2,685个独特的成员，可以在重要化合物的生物合成途径中找到，包括磷霉素、福替米星A、硫链菌素A抗生素和抗病毒药物奥沙诺菌素A。尽管有丰富的酶被确定属于这个亚群，以及它们催化的反应的重要性，但关于它们如何发挥作用的机制细节知之甚少。目前，由于缺乏这类酶的结构信息，以及缺乏具有相同序列和使用相同辅因子组合的先前表征的酶，机制研究受到阻碍。因此，这项建议的目的是确定Adobe Met自由基超家族中依赖钴胺的亚群成员的X射线晶体结构。这些结果将有助于未来机制研究的设计，并为理解Adobe Met和钴胺辅助因子在执行自然化学过程中的协调和相互作用提供了一个框架。

DESCRIPTION (provided by applicant): Over the past few decades, natural products, or chemical compounds derived from plants, animals, or microbes have greatly inspired drug discovery and development. As nature's compounds are more complex and architecturally unique than available man-made drugs, understanding nature's chemistry for engineering these molecules represents a significant milestone in natural product based drug discovery. Many medically important natural product biosynthetic pathways utilize the chemistry of enzymes that were once thought to be part of a tiny subgroup of the S-adenosylmethionine (AdoMet) radical superfamily. Today, this subgroup, the cobalamin-dependent class of AdoMet radical enzymes contains 2,685 unique members and can be found in the biosynthetic pathways of important compounds including fosfomycin, fortimicin A, and thiostrepton A antibiotics, and the anti-viral agent oxetanocin A. Despite the wealth of enzymes identified as belonging to this subgroup and the importance of the reactions they catalyze, there are few mechanistic details known about how they function. Mechanistic studies are currently impeded by a lack of structural information for this class of enzymes and lack of previously characterized enzymes that share a similar sequence and use the same combination of cofactors. Therefore, the objective of this proposal is to determine X-ray crystal structures for members of the cobalamin-dependent subgroup of the AdoMet radical superfamily. These results will aid in the design of future mechanistic studies and provide a framework for understanding the coordination and interplay of AdoMet and cobalamin cofactors in performing nature's chemistry.