Farrow John M, Hudson L Lynn, Wells Greg, Coleman James P, Pesci Everett C
Department of Microbiology and Immunology, The Brody School of Medicine at East Carolina University, Greenville, North Carolina, USA.
Department of Microbiology and Immunology, The Brody School of Medicine at East Carolina University, Greenville, North Carolina, USA
J Bacteriol. 2015 Jun 15;197(12):1988-2002. doi: 10.1128/JB.00246-15. Epub 2015 Apr 6.
Pseudomonas aeruginosa is a Gram-negative bacterium that is ubiquitous in the environment, and it is an opportunistic pathogen that can infect a variety of hosts, including humans. During the process of infection, P. aeruginosa coordinates the expression of numerous virulence factors through the production of multiple cell-to-cell signaling molecules. The production of these signaling molecules is linked through a regulatory network, with the signal N-(3-oxododecanoyl) homoserine lactone and its receptor LasR controlling the induction of a second acyl-homoserine lactone signal and the Pseudomonas quinolone signal (PQS). LasR-mediated control of PQS occurs partly by activating the transcription of pqsR, a gene that encodes the PQS receptor and is necessary for PQS production. We show that LasR interacts with a single binding site in the pqsR promoter region and that it does not influence the transcription of the divergently transcribed gene, nadA. Using DNA affinity chromatography, we identified additional proteins that interact with the pqsR-nadA intergenic region. These include the H-NS family members MvaT and MvaU, and CysB, a transcriptional regulator that controls sulfur uptake and cysteine biosynthesis. We show that CysB interacts with the pqsR promoter and that CysB represses pqsR transcription and PQS production. Additionally, we provide evidence that CysB can interfere with the activation of pqsR transcription by LasR. However, as seen with other CysB-regulated genes, pqsR expression was not differentially regulated in response to cysteine levels. These findings demonstrate a novel role for CysB in influencing cell-to-cell signal production by P. aeruginosa.
The production of PQS and other 4-hydroxy-2-alkylquinolone (HAQs) compounds is a key component of the P. aeruginosa cell-to-cell signaling network, impacts multiple physiological functions, and is required for virulence. PqsR directly regulates the genes necessary for HAQ production, but little is known about the regulation of pqsR. We identified CysB as a novel regulator of pqsR and PQS production, but, unlike other CysB-controlled genes, it does not appear to regulate pqsR in response to cysteine. This implies that CysB functions as both a cysteine-responsive and cysteine-unresponsive regulator in P. aeruginosa.
铜绿假单胞菌是一种革兰氏阴性菌，在环境中普遍存在，是一种机会致病菌，可感染包括人类在内的多种宿主。在感染过程中，铜绿假单胞菌通过产生多种细胞间信号分子来协调众多毒力因子的表达。这些信号分子的产生通过一个调控网络相互关联，信号N-（3-氧代十二烷酰基）高丝氨酸内酯及其受体LasR控制第二种酰基高丝氨酸内酯信号和铜绿假单胞菌喹诺酮信号（PQS）的诱导。LasR介导的对PQS的控制部分是通过激活pqsR的转录来实现的，pqsR是一个编码PQS受体且对PQS产生必不可少的基因。我们发现LasR与pqsR启动子区域的一个单一结合位点相互作用，并且它不影响反向转录基因nadA的转录。使用DNA亲和层析，我们鉴定出了与pqsR-nadA基因间区域相互作用的其他蛋白质。这些包括H-NS家族成员MvaT和MvaU，以及CysB，一种控制硫摄取和半胱氨酸生物合成的转录调节因子。我们发现CysB与pqsR启动子相互作用，并且CysB抑制pqsR转录和PQS产生。此外，我们提供证据表明CysB可以干扰LasR对pqsR转录的激活。然而，正如在其他CysB调控基因中所见，pqsR的表达对半胱氨酸水平没有差异调节。这些发现证明了CysB在影响铜绿假单胞菌细胞间信号产生方面的新作用。
PQS和其他4-羟基-2-烷基喹诺酮（HAQs）化合物的产生是铜绿假单胞菌细胞间信号网络的关键组成部分，影响多种生理功能，并且是毒力所必需的。PqsR直接调节HAQ产生所需的基因，但对pqsR的调节了解甚少。我们鉴定出CysB是pqsR和PQS产生的新型调节因子，但与其他CysB控制的基因不同，它似乎不响应半胱氨酸来调节pqsR。这意味着CysB在铜绿假单胞菌中既作为半胱氨酸响应调节因子又作为半胱氨酸不响应调节因子发挥作用。
