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: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: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: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.
Project description:Exploration of a novel rbcDNA liquid biopsy technique for early detection of colorectal cancer is a promising development in the field of disease diagnosis and screening. This technique has the potential to establish an efficient and sensitive system for the early detection of colorectal cancer, which can provide a new perspective for individual health monitoring.
Project description:Competition for limited iron resources is a key driver of microbial community structure in many regions of the surface ocean. The bacterial siderophores ferrioxamine and amphibactin have been identified in marine surface waters, suggesting that they may represent an important bacterial strategy for obtaining iron from a scarcely populated pool. We screened several strains of marine Vibrio for the presence of putative amphibactin biosynthesis gene homologues and amphibactin production. Whole cell proteomics, siderophore isolation, and isotopically labeled iron uptake experiments were performed. Here, we show that an amphibactin-producing marine bacterium, Vibrio cyclitrophicus str. 1F-53, harbors an independently regulated uptake pathway for ferrioxamines. Proteomic analyses identified upregulation of the amphibactin NRPS system and a putative amphibactin siderophore transporter in response to low iron concentrations. In addition, multiple other transporters were upregulated, however when desferrioxamine was present, amphibactin production decreased and the ferrioxamine receptor increased in abundance. Such cheating phenotypes, which appear widespread among marine amphibactin producers, highlight the strategies that contribute to the fitness of marine bacteria in the face of iron stress. These results demonstrate siderophore producer and cheater phenotypes and highlight the cellular restructuring which is involved due to competition for iron, that shapes the community structure of marine ecosystems.
Project description:Exploiting the symbiotic interaction between crops and nitrogen-fixing bacteria is a simple and ecological solution to promote plants growth in prospective extraterrestrial human outposts. In this study, we investigated the adaptation of the legume symbiont Paraburkholderia phymatum to simulated microgravity (s0-g) at the transcriptome level by performing an RNA-Seq analysis. The results revealed a drastic effect on gene expression, with roughly 23 % of P. phymatum genes being differentially regulated in s0-g. Among those, 951 genes were upregulated and 858 downregulated in the cells grown in s0-g compared to terrestrial gravity (1g). Genes involved in posttranslational modification, proteins turnover and chaperones production were upregulated in s0-g, while those involved in translation, ribosomal structure and biosynthesis, motility or inorganic ions transport were downregulated. Specifically, the whole phm gene cluster, previously predicted to be involved in the production of a hypothetical siderophore, phymabactin, was approximatively 20-fold downregulated in microgravity. Accordingly, a phm-gfp reporter strain showed less expression in s0-g and iron uptake was reduced in microgravity. By constructing a mutant strain (ΔphmJK) we confirmed that the phm gene cluster codes for the only siderophore secreted by P. phymatum. In fact, in contrast to P. phymatum wild-type, ΔphmJK did not produce any siderophores on chrome azurol S plates. These results not only provide a deeper understanding of the physiology of symbiotic organisms exposed to space-like conditions, but also increase our understanding of iron acquisition in rhizobia.