PDF(Pubmed)
Abstract：
Because purine nucleotides are essential for all life, differences between how microbes and humans metabolize purines can be exploited for the development of antimicrobial therapies. While humans biosynthesize purine nucleotides in a 10-step pathway, most microbes utilize an additional 11th enzymatic activity. The human enzyme, aminoimidazole ribonucleotide (AIR) carboxylase generates the product 4-carboxy-5-aminoimidazole ribonucleotide (CAIR) directly. Most microbes, however, require two separate enzymes, a synthetase (PurK) and a mutase (PurE), and proceed through the intermediate, N5-CAIR. Toward the development of therapeutics that target these differences, we have solved crystal structures of the N5-CAIR mutase of the human pathogens Legionella pneumophila (LpPurE) and Burkholderia cenocepacia (BcPurE) and used a structure-guided approach to identify inhibitors. Analysis of the structures reveals a highly conserved fold and active site architecture. Using this data, and three additional structures of PurE enzymes, we screened a library of FDA-approved compounds in silico and identified a set of 25 candidates for further analysis. Among these, we identified several new PurE inhibitors with micromolar IC50 values. Several of these compounds, including the α1-blocker Alfuzosin, inhibit the microbial PurE enzymes much more effectively than the human homologue. These structures and the newly described PurE inhibitors are valuable tools to aid in further studies of this enzyme and provide a foundation for the development of compounds that target differences between human and microbial purine metabolism.
摘要：
因为嘌呤核苷酸对所有生命都至关重要，微生物和人类如何代谢嘌呤之间的差异可以用于开发抗菌疗法。虽然人类在10步途径中生物合成嘌呤核苷酸，大多数微生物利用额外的第11酶活性。人类酶，氨基咪唑核糖核苷酸(AIR)羧化酶直接产生产物4-羧基-5-氨基咪唑核糖核苷酸(CAIR)。大多数微生物，然而,需要两种独立的酶，合成酶（PurK）和变位酶（PurE），并通过中间，N5-CAIR。针对这些差异的治疗方法的发展，我们已经解决了人类病原体嗜肺军团菌（LpPurE）和伯克霍尔德氏菌（BcPurE）的N5-CAIR变位酶的晶体结构，并使用结构指导的方法来鉴定抑制剂。结构分析揭示了高度保守的折叠和活性位点结构。使用这些数据，和三个额外的PuE酶结构，我们筛选了一个FDA批准的化合物库,并鉴定了一组25个候选化合物用于进一步分析.其中,我们鉴定了几种新的PurE抑制剂,其IC50值为微摩尔浓度.这些化合物中的几种，包括α1阻断剂阿夫唑嗪,比人类同源物更有效地抑制微生物PuE酶。这些结构和新描述的PurE抑制剂是有助于进一步研究该酶的有价值的工具，并为开发靶向人类和微生物嘌呤代谢差异的化合物奠定了基础。
