Project description:We investigated the function of the SNX/H-type regulator of G-protein signaling (RGS) protein RGS4 and found alterations in enzyme regulation, stress response, siderophore production and metabolism of several carbon sources in light and darkness
Project description:The aim of the experiment was to identify genes differentially expressed between the susceptible wild type strain P. aeruginosa PAO1 (PT5) and a mutant resistant to a drug-siderophore conjugate, in order to obtain information on the resistance mechanism(s). A mutant of PT5 able to grow at 4 mg/l BAL30072, a drug-siderophore conjugate, was selected in vitro . The susceptible wild type strain PT5 and the mutant (BAL6) were grown in LB medium and the mutant also in the presence of 4 mg/l BAL30072 to mid-exponential growth phase (OD600 =2) in triplicate cultures. RNA was extracted using the RNeasy Kit (Qiagen). A total of nine Affymterix P. aeruginosa arrays were hybridized (one for each replicate) under standard conditions.
Project description:Serratia marcescens is a bacterium frequently found in the environment, but over the last several decades it has evolved into a concerning clinical pathogen, causing fatal bacteremia. To establish such infections, pathogens require specific nutrients; one very limited but essential nutrient is iron. We sought to characterize the iron acquisition systems in S. marcescens isolate UMH9, which was recovered from a clinical bloodstream infection. Using RNA sequencing (RNA-seq), we identified two predicted siderophore gene clusters (cbs and sch) that were regulated by iron. Mutants were constructed to delete each iron acquisition locus individually and in conjunction, generating both single and double mutants for the putative siderophore systems. Mutants lacking the sch gene cluster lost their iron-chelating ability as quantified by the chrome azurol S (CAS) assay, whereas the cbs mutant retained wild-type activity. Mass spectrometry-based analysis identified the chelating siderophore to be serratiochelin, a siderophore previously identified in Serratia plymuthica. Serratiochelin-producing mutants also displayed a decreased growth rate under iron-limited conditions created by dipyridyl added to LB medium. Additionally, mutants lacking serratiochelin were significantly outcompeted during cochallenge with wild-type UMH9 in the kidneys and spleen after inoculation via the tail vein in a bacteremia mouse model. This result was further confirmed by an independent challenge, suggesting that serratiochelin is required for full S. marcescens pathogenesis in the bloodstream. Nine other clinical isolates have at least 90% protein identity to the UMH9 serratiochelin system; therefore, our results are broadly applicable to emerging clinical isolates of S. marcescens causing bacteremia.
Project description:We investigated a paradoxical re-growth of E. coli upon treatment of a novel siderophore-conjugate, LP-600, at concentrations 16-32 times above the minimum inhibitory concentration (MIC).Transcriptome analysis revealed that LP-600 induced the expression of genes involved in SOS response and e14 prophage upon regrowth conditions.
Project description:This study aims at investigating the ability of Pseudomonas aeruginosa to detect the presence of siderophore-antibiotic conjugates in an epithelial cell infection assay. We show that the presence of siderophore-antibiotic conjugates induces the transcription and expression of their corresponding transporters, indicating the bacteria are able to sense the chelators in their environment and adapt their phenotype accordingly.