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多种生物活性的2-烷基-4(1H)-喹诺酮类(AQ)和2-烷基-4-羟基喹啉-N-氧化物。作为群体感应信号分子，2-庚基-4(1H)-喹诺酮(HHQ)和2-庚基-3-羟基-4(1H)-喹诺酮(PQs)参与了毒力因子的产生调控；PQs还具有铁离子螯合和膜改变的特性。2-庚基-4-羟基喹啉-N-氧化物(HQNO)具有抗菌作用，对呼吸电子传递有抑制作用。我们最近分离出红球红球菌BG43，这是第一株被描述为专门降解PQS和转化HQNO的细菌。BG43菌株编码HHQ和PQS转化酶的Aqd基因簇在脓肿分枝杆菌复合体的细菌中也是保守的，我们观察到几株临床脓肿分支杆菌对HQNO的转化和PQS和/或HHQ的降解。这些发现为鉴定参与HQNO解毒的酶、鉴定PQS特有的酶并评估它们作为群体猝灭剂以及研究AQ降解和HQNO解毒在细菌种间相互作用中的相关性开辟了新的视角。所有菌株的基因组序列都是可用的。该计划的目的是：(1)阐明HQNO转化的途径(S)：代谢物的特性和提出的关键酶-N-氧化物还原酶的鉴定。(2)鉴定红城葡萄球菌BG43和脓肿分支杆菌菌株PQS-双加氧酶的催化效率和稳定性，并检测最稳定、活性最高的酶(S)对铜绿假单胞菌毒力因子产生的干扰作用。(3)研究脓肿分支杆菌对铜绿假单胞菌基于AQ的群体感应和基于HQNO的抗生素的潜在干扰作用。为此，我们将表征临床脓肿分支杆菌的acd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)与不同能够/不能降解PQS和/或HQNO的脓肿分支杆菌菌株共培养时的生理反应，并确定脓肿分支杆菌和铜绿假单胞菌在共培养中的生长。

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.