Characterization of polyamine biosynthetic enzymes from human gut microbes associated with colon and pancreatic cancer

项目摘要 人类癌细胞中的多胺生物合成是一个长期存在的治疗目标。越来越多的证据 表明肠道微生物产生的多胺有助于结肠和胰腺癌的进展， 癌肠道细菌生物合成多胺亚精胺的途径与人类不同 使这种细菌途径成为独特的药物靶点。这条通路中的两种中心酶， 羧胸苷脱氢酶和羧胸苷脱羧酶，只收到有限的 特征化我们建议解决的第一个结构的羧基胸苷脱氢酶， 发展动力学和结构模型描述的功能，羧基胸苷脱氢酶 和来自拟杆菌属和梭菌属的主要肠道成分中的羧胸苷脱羧酶。 这些目标是未来机制指导药物设计计划的必要前提。长-- 这项工作的长期目标是为结肠直肠癌和胰腺癌的治疗开辟新的途径。有趣的是， 来自许多肠道属的预测的多胺生物合成酶的基因似乎编码冗余的 生产亚精胺的途径。我们假设这些路径不是冗余的，而是生成 独特的聚胺产品。我们建议使用LC-TQ-MS分析来描绘多胺产物， 在梭菌中发现的明显多余的酶对。亚精胺合酶是这一目标的关键焦点， 该酶原核直向同源物已经显示出除了 亚精胺这项工作将扩大我们对键内发现的功能变化的基本理解 肠道微生物代谢途径：多胺生物合成。

PROJECT SUMMARY Polyamine biosynthesis in human cancer cells is a long-standing therapeutic target. Accumulating evidence suggests that polyamine production by gut microbes contributes to the progression of colon and pancreatic cancer. Biosynthesis of the polyamine spermidine by gut bacteria follows a pathway distinct from the human pathway making this bacterial pathway a unique drug target. The two central enzymes in this pathway, carboxyspermidine dehydrogenase and carboxyspermidine decarboxylase, have received only limited characterization. We propose to solve the first structure of a carboxyspermidine dehydrogenase and to development kinetic and structural models describing the function of both carboxyspermidine dehydrogenase and carboxyspermidine decarboxylase in major gut constituents from the Bacteroides and Clostridium genera. These aims serve as a necessary precursor to a future program of mechanism-guided drug design. The long- term goal of this work is to open new avenues for the treatment of colorectal and pancreatic cancer. Interestingly, the genes of predicted polyamine biosynthetic enzymes from many gut genera appear to encode redundant paths toward the production of spermidine. We hypothesize that these paths are not redundant, but generate unique polyamine products. We propose the use of LC-TQ-MS assays to delineate the polyamine products from apparently redundant enzyme pairs found in Clostridium. Spermidine synthase is a key focus of this aim because the prokaryotic orthologs of this enzyme have been shown to produce a variety of polyamine products besides spermidine. This work will expand our fundamental understanding of the functional variations found within a key gut microbe metabolic pathway: polyamine biosynthesis.