Inactivation of Pseudomonas aeruginosa 2-alkyl-4-hydroxyquinoline-type quorum sensing signals and antibiotics by Rhodococcus erythropolis and Mycobacterium abscessus

条件致病菌铜绿假单胞菌产生大量具有生物活性的2-烷基-4(1H)-喹诺酮类药物（AQ）和2-烷基-4-羟基喹啉- n -氧化物。2-庚基-4(1H)-喹诺酮（HHQ）和2-庚基-3-羟基-4(1H)-喹诺酮（PQS）作为群体感应信号分子参与毒力因子产生的调控；此外，PQS还具有铁螯合和膜改变特性。2-庚基-4-羟基喹啉- n -氧化物（HQNO）具有抗菌作用，可抑制呼吸道电子转移。我们最近分离出红红红球菌BG43，这是第一个被描述的特异性降解PQS和转化HQNO的细菌菌株。菌株BG43中编码HHQ和PQS转化酶的aqd基因簇在脓肿分枝杆菌复合体细菌中也有保守性，我们观察了几种临床脓肿分枝杆菌菌株的HQNO转化和PQS和/或HHQ降解。这些发现为鉴定参与HQNO解毒的酶、鉴定pqs特异性酶并评估其作为群体猝灭剂的作用、研究细菌种间相互作用中AQ降解与HQNO解毒的相关性开辟了新的视角。所有菌株的基因组序列是可用的。拟建项目旨在：(1)阐明HQNO转化的途径：代谢产物的表征和拟建立的关键酶n -氧化物还原酶的鉴定。(2)对红孢霉BG43和部分脓肿分枝杆菌菌株的pqs -双加氧酶的催化效率和稳定性进行了表征，并测试了最稳定、最具活性的酶对铜绿假单胞菌毒力因子产生干扰的潜力。(3)表征脓肿分枝杆菌对铜绿假单胞菌基于空气质量的群体感应和基于hqno的抗生素的干扰潜力。为此，我们将表征临床脓肿分枝杆菌菌株aqd基因簇对PQS的转录反应。我们还将分析铜绿假单胞菌（野生型和pqs突变体）与不同的能/不能降解pqs和/或HQNO的脓肿分枝杆菌菌株共培养时的生理反应，并测定脓肿分枝杆菌和铜绿假单胞菌菌株在共培养中的生长情况。

The opportunistic pathogen Pseudomonas aeruginosa produces a number of bioactive 2-alkyl-4(1H)-quinolones (AQ) and 2-alkyl-4-hydroxyquinoline-N-oxides. As quorum sensing signal molecules, 2-heptyl-4(1H)-quinolone (HHQ) and 2-heptyl-3-hydroxy-4(1H)-quinolone (PQS) are involved in the regulation of virulence factor production; PQS moreover has iron-chelating and membrane altering properties. 2-Heptyl-4-hydroxyquinoline-N-oxide (HQNO) has antibiotic effects, acting as inhibitor of respiratory electron transfer. We recently isolated Rhodococcus erythropolis BG43, the first bacterial strain described to specifically degrade PQS and to convert HQNO. The aqd gene cluster which in strain BG43 codes for the enzymes mediating HHQ and PQS conversion is also conserved in bacteria of the Mycobacterium abscessus complex, and we observed HQNO conversion and PQS and/or HHQ degradation by several clinical M. abscessus strains. These findings open up new perspectives for identifying enzymes involved in HQNO detoxification, for characterizing PQS-specific enzymes and assessing them as quorum quenching agents, and for studying the relevance of AQ degradation and HQNO detoxification in bacterial inter-species interactions. The genome sequences of all strains are available.The proposed project aims at: (1) Elucidating the pathway(s) of HQNO conversion: characterization of metabolites and identification of the proposed key enzyme, an N-oxide reductase. (2) Characterizing the catalytic efficiency and stability of PQS-dioxygenases of R. erythropolis BG43 and of selected M. abscessus strains, and testing the potential of the most stable and most active enzyme(s) to interfere with virulence factor production of P. aeruginosa. (3) Characterizing the potential of M. abscessus to interfere with AQ-based quorum sensing and HQNO-based antibiosis of P. aeruginosa. To this end, we will characterize the transcriptional response of the aqd gene clusters of clinical M. abscessus strains to PQS. We also will analyze the physiological response of P. aeruginosa (wild-type and pqs mutants) in co-culture with different M. abscessus strains that are able/unable to degrade PQS and/or HQNO and determine growth of M. abscessus and P. aeruginosa strains in the co-cultures.