Biology subjects

Trouillon, J.

Publications and source records attributed to Trouillon, J..

3 recordsLinked to original sources

bioRxiv2021

Molecular features underlying Pseudomonas aeruginosa persistence in human plasma

Pseudomonas aeruginosa, an opportunistic Gram-negative pathogen, is a leading cause of bacteremia with a high mortality rate. We recently reported that P. aeruginosa forms a persister-like sub-population of evaders in human plasma and blood. However, the molecular mechanisms underlying the formation of evaders remained unknown. Here, using a gain-of-function genetic screen, we examined the molecular determinants of P. aeruginosa persistence in plasma. We found that, among other factors, ATP and biotin availability greatly influence bacterial survival in plasma; mutants in pur and bio genes display higher tolerance and persistence, respectively. Electron microscopy combined with energy-dispersive X-ray spectroscopy (EDX) revealed the formation of polyphosphate granules upon incubation in plasma in several clinical strains, implying the bacterial response to a low-energy stress signal. Indeed, mutants with transposon insertions in ppk genes were eliminated in the plasma. Analysis of several steps of the complement cascade and exposure to an outer-membrane-impermeable drug, nisin, suggested that the mutants impede membrane attack complex (MAC) activity per se. Through this study, we shed light on P. aeruginosa response to the plasma conditions and discovered the multifactorial origin of bacterial resilience to MAC that provides a comprehensive picture of the complex interplay between P. aeruginosa and the human complement system. Author summaryPersistence of bacterial pathogens is a main cause of treatment failure and establishment of chronic bacterial infection. Despite innate immune responses, some bacteria may persist in human blood and plasma. Here we used a genome-wide screen to investigate the molecular determinants influencing Pseudomonas aeruginosa persistence in human plasma facing the complement system. Alongside a multifactorial strategy, we found intracellular levels of ATP and biotin to significantly influence bacterial capacity to deal with membrane attack complex (MAC)-dependent killing. These results underline the need to understand the complex interplay between bacterial pathogens and the human immune system when seeking to develop efficient antibacterial strategies.

microbiology↗

bioRxiv2021

Determination of the Two-Component Systems regulatory network reveals core and accessory regulations across Pseudomonas aeruginosa lineages

Pseudomonas aeruginosa possesses one of the most complex bacterial regulatory networks, which largely contributes to its success as a human opportunistic pathogen. However, most of its transcription factors (TFs) are still uncharacterized and the potential intra-species variability in regulatory networks has been mostly ignored so far. Here, to provide a first global view of the two-component systems (TCSs) regulatory network in P. aeruginosa, we produced and purified all DNA-binding TCS response regulators (RRs) and used DAP-seq to map the genome-wide binding sites of these 55 TFs across the three major P. aeruginosa lineages. The resulting networks encompass about 40% of all genes in each strain and contain numerous new important regulatory interactions across most major physiological processes, including virulence and antibiotic resistance. Strikingly, the comparison between the three representative strains shows that about half of the detected targets are specific to only one or two of the tested strains, revealing a previously unknown large functional diversity of TFs within a single species. Three main mechanisms were found to drive this diversity, including differences in accessory genome content, as exemplified by the strain-specific plasmid in the IHMA87 outlier strain which harbors numerous binding sites of chromosomally-encoded RRs. Additionally, most RRs display potential auto-regulation or RR-RR cross-regulation, bringing to light the vast complexity of this network. Overall, we provide the first complete delineation of the TCS regulatory network in P. aeruginosa that will represent an important resource for future studies on this pathogen.

microbiology↗

bioRxiv2020

Transcription inhibitors with XRE DNA-binding and cupin signal-sensing domains drive metabolic diversification in Pseudomonas

Transcription factors (TFs) are instrumental in the bacterial response to new environmental conditions. They can act as direct signal sensors and subsequently induce changes in gene expression leading to physiological adaptation. Here, by combining RNA-seq and DAP-seq, we studied a family of eight TFs in Pseudomonas aeruginosa. This family, encompassing TFs with XRE-like DNA-binding and cupin signal-sensing domains, includes the metabolic regulators ErfA, PsdR and PauR and five so far unstudied TFs. The genome-wide delineation of their regulons identified 39 regulatory interactions with genes mostly involved in metabolism. We found that the XRE-cupin TFs are inhibitors of their neighboring genes, forming local, functional units encoding proteins with functions in condition-specific metabolic pathways. The phylogenetic analysis of this family of regulators across the Pseudomonas genus revealed a wide diversity of such metabolic regulatory modules and identified species with potentially higher metabolic versatility. Numerous uncharacterized XRE-cupin TFs were found near metabolism-related genes, illustrating the need of further systematic characterization of transcriptional regulatory networks in order to better understand the mechanisms of bacterial adaptation to new environments. IMPORTANCEBacteria of the Pseudomonas genus, including the major human pathogen P. aeruginosa, are known for their complex regulatory networks and high number of transcription factors, which contribute to their impressive adaptive ability. However, even in the most studied species, most of the regulators are still uncharacterized. With the recent advances in high-throughput sequencing methods, it is now possible to fill this knowledge gap and help understanding how bacteria adapt and thrive in new environments. By leveraging these methods, we provide an example of a comprehensive analysis of an entire family of transcription factors and bring new insights into metabolic and regulatory adaptation in the Pseudomonas genus.

microbiology↗