Bacterial metabolism of 2-methylquinoline and naturally occurring 2-alkyl-4(1H) quinolones: (I) Transcriptional regulation of 2-methylquinoline degradation, (II) Bacterial strains and enzymes for the inactivation of 2-alkyl-4(1H)quinolones

2-节杆菌Rü 61 a降解甲基喹啉生成邻氨基苯甲酸盐的过程由位于线性质粒pAL 1上的两个“上途径”操纵子编码。邻氨基苯甲酸可以通过染色体儿茶酚途径降解，然而，pAL 1的另一个操纵子被提出编码通过辅酶A中间体转化邻氨基苯甲酸的“较低途径”酶。两个PaaX型调节剂参与pAL 1的分解代谢操纵子的转录控制，鉴于PaaX蛋白仅限于苯乙酸分解代谢子的当前概念，这是一个意外的发现。该项目的第一部分旨在表征pAL 1分解代谢操纵子的转录调控。将讨论以下主题：（i）分解代谢启动子和PaaX样基因启动子对碳化合物的反应活性;（ii）PaaX样蛋白在调节分解代谢操纵子中的作用，以及它们的基因产物对PaaX基因的可能的自调节/相互调节;（iii）PaaX反应操纵子序列的鉴定，以及PaaX蛋白的效应特异性;（iv）鉴定其他启动子结合蛋白;（v）表征pAL 1编码的邻氨基苯甲酸转化基因。该项目的第二部分解决了细菌如何降解天然存在的烷基喹诺酮类药物的问题，如2-庚基-4（1H）喹诺酮和2-庚基-3-羟基-4（1H）喹诺酮，这是铜绿假单胞菌的重要群体感应信号分子。目标是鉴定用于灭活这些化合物的新型酶。

2-Methylquinoline degradation by Arthrobacter nitroguajacolicus Rü61a to anthranilate is encoded by two “upper pathway” operons located on the linear plasmid pAL1. Anthranilate can be degraded via a chromosomal catechol pathway, however, another operon of pAL1 was proposed to encode “lower pathway” enzymes for anthranilate conversion via coenzyme A intermediates. Two PaaX-type regulators are involved in transcriptional control of the catabolic operons of pAL1, which in view of the current notion that PaaX proteins are restricted to the phenylacetate catabolon is an unexpected finding. The first part of the project aims at characterizing the transcriptional regulation of catabolic operons of pAL1. The following topics will be addressed: (i) Activities of catabolic promoters and of promoters of the paaX-like genes in response to carbon compounds; (ii) role of PaaX-like proteins in regulation of catabolic operons, and possible auto-regulation/reciprocal regulation of paaX genes by their gene products; (iii) identification of PaaX-responsive operator sequences, and effector specificity of the PaaX proteins; (iv) identification of other promoter-binding proteins; (v) characterization of pAL1-encoded genes for anthranilate conversion. The second section of the project addresses the question how bacteria degrade naturally occurring alkylquinolones, such as 2-heptyl-4(1H)quinolone and 2-heptyl-3-hydroxy-4(1H)quinolone, which are important quorum sensing signalling molecules of Pseudomonas aeruginosa. The goal is to identify novel enzymes for the inactivation of these compounds.