Project description:GacS/GacA is a widely distributed two-component system playing an essential role as a key global regulator, although its characterization in phytopathogenic bacteria has been deeply biased, being intensively studied in pathogens of herbaceous plants but barely investigated in pathogens of woody hosts. P. savastanoi pv. savastanoi (Psv) is characterized by inducing tumours in the stem and branches of olive trees. In this work, the model strain Psv NCPPB 3335 and a mutant derivative with a complete deletion of gene gacA were subjected to RNA-Seq analyses in a minimum medium and a medium mimicking in planta conditions, accompanied by RT-qPCR analyses of selected genes and phenotypic assays. These experiments indicated that GacA participates in the regulation of at least 2152 genes in strain NCPPB 3335, representing 37.9 % of the annotated CDSs. GacA also controls the expression of diverse rsm genes, and modulates diverse phenotypes, including motility and resistance to oxidative stresses. As occurs with other P. syringae pathovars of herbaceous plants, GacA regulates the expression of the type III secretion system and cognate effectors. In addition, GacA also regulates the expression of WHOP genes, specifically encoded in P. syringe strains isolated from woody hosts, and genes for the biosynthesis of phytohormones. A gacA mutant of NCPPB 3335 showed increased virulence, producing large immature tumours with high bacterial populations, but showed a significantly reduced competitiveness in planta. Our results further extend the role of the global regulator GacA in the virulence and fitness of a P. syringae pathogen of woody hosts.
Project description:Botryosphaeriaceae is an important fungal family that can colonize a wide range of woody hosts including economically important plants and cause serious diseases worldwide. To uncover the virulence variation in Lasiodiplodia theobromae, we sequenced the transcriptome of Las1 in L. theobromae inoculated with the stems of V.vinifera using dual-RNAseq method. We found a lot of expanded genes were induced after inoculated with grapevine compared with the transcriptome of Las1 that was maintained in PDA under the same condition.
Project description:Francisella tularensis is a Gram-negative bacterium that causes a fatal human disease known as tularemia. The Centers for Disease Control have classified F. tularensis as Category A Tier-1 Select Agent. The virulence mechanisms of Francisella are not entirely understood. Francisella possesses very few transcription regulators, and most of these regulate the expression of genes involved in intracellular survival and virulence. The F. tularensis genome sequence analysis reveals an AraC (FTL_0689) transcriptional regulator homologous to the AraC/XylS family of transcriptional regulators. In Gram-negative bacteria, AraC activates genes required for L-arabinose utilization and catabolism. The role of the FTL_0689 regulator in F. tularensis is not known. In this study, we characterized the role of FTL_0689 in gene regulation of F. tularensis and investigated its contribution to intracellular survival and virulence. The results demonstrate that FTL_0689 in Francisella is not required for L-arabinose utilization. Instead, FTL_0689 specifically regulates the expression of the oxidative and global stress response, virulence, metabolism, and other key pathways genes required by Francisella when exposed to oxidative stress. The FTL_0689 mutant is attenuated for intramacrophage growth, and mice infected with the FTL_0689 mutant survive better than wild-type F. tularensis LVS infected mice. Based on the deletion mutant phenotype, FTL_0689 was termed osrR (oxidative stress response regulator). Altogether, this study elucidates the role of the osrR transcriptional regulator in tularemia pathogenesis.
Project description:Pseudomonas aeruginosa encodes a large set of transcriptional regulators which allow to modulate and manage cellular metabolism to survive in variable environmental conditions, including the human body. The AraC family regulators are an abundant group of transcriptional regulators in bacteria, mostly acting as gene expression activators controlling diverse cellular functions e.g. carbon metabolism, stress response and virulence. PA3027 protein from P. aeruginosa has been classified in silico as a putative AraC-type transcriptional regulator. Comparative transcriptome analysis of P. aeruginosa PAO1161 overexpressing PA3027 versus empty vector control revealed a spectacular over 15-fold up-regulation of expression of pa3026-pa3024, PA3464 and PA3342 genes potentially involved in glycerolipid metabolism. Concomitantly, the ChIP-seq analysis using FLAG-PA3027 under mild overproduction conditions revealed at least 22 PA3027 binding sites in the PAO1161 genome, including promoter regions of genes showing a major increase in expression in response to PA3027 excess. The presented data showed that PA3027 acts as the transcriptional regulator in P. aeruginosa activating genes engaged in glycerolipid metabolism.
Project description:Pseudomonas aeruginosa encodes a large set of transcriptional regulators which allow to modulate and manage cellular metabolism to survive in variable environmental conditions, including the human body. The AraC family regulators are an abundant group of transcriptional regulators in bacteria, mostly acting as gene expression activators controlling diverse cellular functions e.g. carbon metabolism, stress response and virulence. PA3027 protein from P. aeruginosa has been classified in silico as a putative AraC-type transcriptional regulator. Comparative transcriptome analysis of P. aeruginosa PAO1161 overexpressing PA3027 versus empty vector control revealed a spectacular over 15-fold up-regulation of expression of pa3026-pa3024, PA3464 and PA3342 genes potentially involved in glycerolipid metabolism. Concomitantly, the ChIP-seq analysis using FLAG-PA3027 under mild overproduction conditions revealed at least 22 PA3027 binding sites in the PAO1161 genome, including promoter regions of genes showing a major increase in expression in response to PA3027 excess. The presented data showed that PA3027 acts as the transcriptional regulator in P. aeruginosa activating genes engaged in glycerolipid metabolism.
Project description:Vibrio campbellii BAA-1116 was used as a Harveyi clade model organism to determine the impact of indole signaling on virulence. Gene expression analysis of V. campbellii grown in LB35 broth with or without 100 μM indole revealed that indole decreased: (1) V. campbellii virulence in shrimp and prawn challenge assays, (2) exopolysaccharide production, and (3) swimming motility. The results also indicated that indole inhibits quorum sensing-regulated bioluminescence and blocks the three-channel quorum sensing system by interfering with quorum sensing signal transduction.
Project description:The gene expression profiles were investigated and compared in spleen, lungs and liver of susceptible (BALB/c) and resistant (C57BL/6) hosts to identify genes participated in survival and virulence functions encoded in the B. pseudomallei genome. Subsequently, genes with unknown function and located with virulence gene clusters or suspected to be transcription regulator were selected for a novel virulence gene investigation
Project description:Previous studies have shown serotonin and indole downregulate expression of virulence genes in EHEC, here we demonstrate the combinatorial effect of serotonin and indole on EHEC transcriptome
Project description:A common genomic feature of most EAEC strains is the presence of a virulence plasmid termed pAA. Plasmid-encoded virulence determinants are, among others, a transcriptional activator termed AggR, a member of the AraC-XylS family of transcription factors. We have previously determined the direct correlation between (p)ppGpp, expression of AggR and biofilm development in strain EAEC 042 (https://doi.org/10.3389/fmicb.2018.00717). In this work we characterize a novel variant of the aggR gene. We modified its 3´UTR by insertion of a FRT sequence, which have generated a series of different phenotypes. We used RNA-seq to compare the transcriptome of the wt strain and its aggR3UTRFRT variant grown at 37ºC in LB medium.
