Dataset Information

The Small RNA ErsA Impacts the Anaerobic Metabolism of Pseudomonas aeruginosa Through Post-Transcriptional Modulation of the Master Regulator Anr

ABSTRACT: Pseudomonas aeruginosa is one of the most critical opportunistic pathogens in humans, able to cause both lethal acute and chronic lung infections. In previous work, we indicated that the small RNA ErsA plays a role in the regulatory network of P. aeruginosa pathogenicity in airways infection. To give further insight into the lifestyle functions that could be either directly or indirectly regulated by ErsA during infection, we reanalyzed the categories of genes whose transcription appeared dysregulated in an ersA knock-out mutant of the P. aeruginosa PAO1 reference strain. This preliminary analysis indicated ErsA as a candidate co-modulator of denitrification and in general, the anaerobiosis response, a characteristic physiologic state of P. aeruginosa during chronic infection of the lung of cystic fibrosis (CF) patients. To explain the pattern of dysregulation of the anaerobic-lifestyle genes in the lack of ErsA, we postulated that ErsA regulation could target the expression of Anr, a well-known transcription factor that modulates a broad regulon of anoxia-responsive genes, and also Dnr, required for the transcription activation of the denitrification machinery. Our results show that ErsA positively regulates Anr expression at the post-transcriptional level while no direct ErsA-mediated regulatory effect on Dnr was observed. However, Dnr is transcriptionally downregulated in the absence of ErsA and this is consistent with the well-characterized regulatory link between Anr and Dnr. Anr regulatory function is critical for P. aeruginosa anaerobic growth, both through denitrification and fermentation of arginine. Interestingly, we found that, differently from the laboratory strain PAO1, ErsA deletion strongly impairs the anaerobic growth by both denitrification and arginine fermentation of the RP73 clinical isolate, a multi-drug resistant P. aeruginosa CF-adapted strain. This suggests that P. aeruginosa adaptation to CF lung might result in a higher dependence on ErsA for the transduction of the multiple signals to the regulatory network of key functions for survivance in such a complex environment. Together, our results suggest that ErsA takes an upper place in the regulatory network of airways infection, transducing host inputs to biofilm-related factors, as underlined in our previous reports, and to functions that allow P. aeruginosa to thrive in low-oxygen conditions.

SUBMITTER: Ferrara S

PROVIDER: S-EPMC8575079 | biostudies-literature |

REPOSITORIES: biostudies-literature

ACCESS DATA

Similar Datasets

Project description:UnlabelledIn Pseudomonas aeruginosa, the transcription factor Anr controls the cellular response to low oxygen or anoxia. Anr activity is high in oxygen-limited environments, including biofilms and populations associated with chronic infections, and Anr is necessary for persistence in a model of pulmonary infection. In this study, we characterized the Anr regulon in biofilm-grown cells at 1% oxygen in the laboratory strain PAO1 and in a quorum sensing (QS)-deficient clinical isolate, J215. As expected, transcripts related to denitrification, arginine fermentation, high-affinity cytochrome oxidases, and CupA fimbriae were lower in the Δanr derivatives. In addition, we observed that transcripts associated with quorum sensing regulation, iron acquisition and storage, type VI secretion, and the catabolism of aromatic compounds were also differentially expressed in the Δanr strains. Prior reports have shown that quorum sensing-defective mutants have higher levels of denitrification, and we found that multiple Anr-regulated processes, including denitrification, were strongly inversely proportional to quorum sensing in both transcriptional and protein-based assays. We also found that in LasR-defective strains but not their LasR-intact counterparts, Anr regulated the production of the 4-hydroxy-2-alkylquinolines, which play roles in quorum sensing and interspecies interactions. These data show that Anr was required for the expression of important metabolic pathways in low-oxygen biofilms, and they reveal an expanded and compensatory role for Anr in the regulation of virulence-related genes in quorum sensing mutants, such as those commonly isolated from infections.ImportancePseudomonas aeruginosa causes acute ocular, soft tissue, and pulmonary infections, as well as chronic infections in the airways of cystic fibrosis patients. P. aeruginosa uses quorum sensing (QS) to regulate virulence, but mutations in the gene encoding the master regulator of QS, lasR, are frequently observed in clinical isolates. We demonstrated that the regulon attributed to Anr, an oxygen-sensitive transcription factor, was more highly expressed in lasR mutants. Furthermore, we show that Anr regulates the production of several different secreted factors in lasR mutants. These data demonstrate the importance of Anr in naturally occurring quorum sensing mutants in the context of chronic infections.

Project description:Pseudomonas aeruginosa, one of the most common pathogens in hospital-acquired infections, is tightly controlled by a multilayered regulatory network, including the quorum sensing system (QS), the type VI secretion system (T6SS), and resistance to host immunity. We found that the P. aeruginosa 3880 (PA3880) gene, which encodes an unknown protein, acts as a regulator of anaerobic metabolism in response to oxidative stress and virulence in P. aeruginosa More than 30 PA3880 homologs were found in other bacterial genomes, indicating that PA3880 is widely distributed in the Bacteria kingdom as a highly conserved gene. Deletion of the PA3880 gene changed the expression levels of more than 700 genes, including a group of virulence genes, under both aerobic and anaerobic conditions. To further study the mechanisms of PA3880-mediated regulation in virulence, we utilized a bacterial two-hybrid assay and found that the PA3880 protein interacted directly with QS regulator MvfR and anaerobic regulator Anr. Loss of the PA3880 protein significantly blunted the pathogenicity of P. aeruginosa, resulting in increased host survival, decreased bacterial burdens, reduced inflammatory responses, and fewer lung injuries in challenged mice hosts. Mechanistically, we found that Cys44 was a critical site for the full function of PA3880 in influencing alveolar macrophage phagocytosis and bacterial clearance. We also found that AnvM directly interacted with host receptors Toll-like receptor 2 (TLR2) and TLR5, which might lead to activation of the host immune response. Hence, we gave the name AnvM (anaerobic and virulence modulator) to the PA3880 protein. This characterization of AnvM could help to uncover new targets and strategies to treat P. aeruginosa infections.IMPORTANCE Infections by Pseudomonas aeruginosa, one of the most frequently isolated human pathogens, can create huge financial burdens. However, knowledge of the molecular mechanisms involved in the pathogenesis of P. aeruginosa remains elusive. We identified AnvM as a novel regulator of virulence in P. aeruginosa Deletion of anvM altered the expression levels of more than 700 genes under aerobic and anaerobic conditions, including quorum sensing system genes and oxidative stress resistance genes. AnvM directly interacted with MvfR and Anr, thus regulating their downstream genes. More importantly, AnvM directly bound to TLR2 and TLR5, which turn on the host immune response. These findings provide insights into the significance of AnvM homologs in pathogenic bacteria and suggest a potential drug target against bacterial infection.

Dataset Information

The Small RNA ErsA Impacts the Anaerobic Metabolism of Pseudomonas aeruginosa Through Post-Transcriptional Modulation of the Master Regulator Anr

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets