A new look at the biosynthesis of 4-hydroxy-2-alkylquinolines in Pseudomonas aeruginosa

铜绿假单胞菌中 4-羟基-2-烷基喹啉生物合成的新视角

• 批准号: 38364-2012
• 负责人: Lépine, François
• 金额: $ 2.04万
• 依托单位: Institut national de la recherche scientifique
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2014
• 资助国家: 加拿大
• 起止时间: 2014-01-01 至 2015-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=544818
• 关键词: new; look; biosynthesis; hydroxy; alkylquinolines

This research program is aimed at deciphering the biosynthesis of 4-hydroxy-2-alkylquinolines (HAQs), which are a class of compounds that are involved in "Quorum Sensing", a mode of communication between bacteria. HAQs are produced by Pseudomonas aeruginosa, an opportunistic pathogen that uses Quorum Sensing to control the expression of virulence factors. Inhibiting the production of HAQs in this bacterium leads to a considerable decrease of its virulence. However, the biosynthesis of HAQs is not fully elucidated and in order to efficiently counter the production of these signaling compounds, it is important to find the role of the enzymes and intermediates involved in their biosynthesis. Although we know that the genes from the pqsABCDE operon are required for HAQ synthesis, the role of the enzymes that they encode is only partially known. Since the discovery of HAQs in the mid 1950s, it was believed that 3-ketofatty acids are intermediates in the biosynthesis of HAQs. In preliminary experiments, we discovered that instead of 3-ketofatty acids, fatty acids were the intermediates involved. This paradigm change brings new light on the role of some of the enzymes implicated in this biosynthesis pathway. Thus we now think that HAQ biosynthesis is a two-step process in which PqsD is responsible for the coupling of anthranilic acid with a malonate derivative to produce 2-amino-benzoylacetic acid and that this intermediate reacts with a fatty acid to produce HAQs. We will confirm this hypothesis by purifying the enzymes PqsB and PqsC that we hypothesize are involved in this second step. We also previously found a series of compounds that seem to inhibit specifically PqsC and/or PqsB. Once the specific role these two enzymes will be understood, we will study their inhibition by these compounds. We will look for analogs of these compounds that might be more active than those we already have. Our long-term goal is to develop a new way to inhibit infections by P. aeruginosa by targeting their quorum sensing, which would be an alternative to the use of antibiotics, an approach which leads to the development of resistance.

该研究项目旨在破译4-羟基-2-烷基喹啉（HAQs）的生物合成，这是一类参与“群体感应”的化合物，是细菌之间的一种交流模式。haq是由铜绿假单胞菌产生的，这是一种利用群体感应控制毒力因子表达的机会性病原体。在这种细菌中抑制haq的产生导致其毒力的显著降低。然而，haq的生物合成尚未完全阐明，为了有效地对抗这些信号化合物的产生，找到参与其生物合成的酶和中间体的作用是很重要的。虽然我们知道来自pqsABCDE操纵子的基因是HAQ合成所必需的，但它们编码的酶的作用只是部分已知。自20世纪50年代中期发现HAQs以来，人们认为3-酮脂肪酸是HAQs生物合成的中间体。在初步实验中，我们发现参与的中间产物不是3-酮脂肪酸，而是脂肪酸。这种模式的改变为一些酶在生物合成途径中的作用带来了新的认识。因此，我们现在认为HAQ的生物合成是一个两步过程，其中PqsD负责将邻氨基苯甲酸与丙二酸酯衍生物偶联产生2-氨基苯甲酰乙酸，该中间体与脂肪酸反应产生HAQ。我们将通过纯化我们假设参与第二步的酶PqsB和PqsC来证实这一假设。我们之前也发现了一系列似乎特异性抑制PqsC和/或PqsB的化合物。一旦了解了这两种酶的具体作用，我们将研究这些化合物对它们的抑制作用。我们将寻找这些化合物的类似物，它们可能比我们现有的化合物更有活性。我们的长期目标是开发一种新的方法，通过针对P. aeruginosa的群体感应来抑制其感染，这将是使用抗生素的替代方法，这种方法会导致耐药性的产生。