RNA-seq for RpoN

Pseudomonas aeruginosa is a Gram-negative opportunistic pathogen of humans, most notably those with cystic fibrosis or whose immune systems are compromised. As a global regulator, RpoN has been characterized to control a group of virulence-related factors and quorum sensing (QS) genes in P. aeruginosa, but its detailed molecular regulatory mechanism is largely elusive. To further gain insights into the direct targets of RpoN in vivo, this study focused on identifying the potential targets of RpoN directly regulating QS system and T6SS. We performed a chromatin immunoprecipitation coupled to high-throughput sequencing (ChIP-seq) assay that identified 1, 068 binding sites of RpoN, including mostly metabolic genes, a group of genes in QS (lasI, rhlI and pqsR) and type VI secretion system (T6SS) (hcpA and hcpB). The direct regulation of these genes by RpoN has been biochemically and genetically verified. Results revealed that, on one hand, the deletion of rpoN resulted in reduced production of pyocyanin, motility and proteolytic activity. On the other hand, the production of rhamnolipids and biofilm formation was higher in the RpoN mutant than in the wild-type. In sum, the results indicated that RpoN had direct and profound effects on QS and T6SS, which provides new cues to better understand the detailed regulatory networks of virulence. RNA-seq for RpoN