In vivo fosA acquisition in Escherichia col
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PROVIDER: PRJEB32329 | ENA |
REPOSITORIES: ENA
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Project description:Fosfomycin is a bactericidal antibiotic, analogous to phosphoenolpyruvate (PEP) that exerts its activity by inhibiting the activity of MurA. This enzyme catalyzes the first step of peptidoglycan biosynthesis, the transfer of enolpyruvate from PEP to uridine- diphosphate-N-acetylglucosamine. Fosfomycin is increasingly used in the last years, mainly for treating infections caused by Gram-negative multidrug resistant bacteria as Stenotrophomonas maltophilia, an opportunistic pathogen characterized by its low susceptibility to antibiotics of common use. The mechanisms of mutational resistance to fosfomycin in Stenotrophomonas maltophilia were studied in the current work. None of the mechanisms so far described for other organisms, which include the production of fosfomycin inactivating enzymes, target modification, induction of alternative peptidoglycan biosynthesis pathway and the impaired entrance of the antibiotic, are involved in the acquisition of such resistance by this bacterial species. Rather the unique cause of resistance in the studied mutants is the mutational inactivation of different enzymes belonging to the Embden-Meyerhof-Parnas central metabolism pathway. The amount of intracellular fosfomycin accumulation did not change in any of these mutants showing that neither the inactivation nor the transport of the antibiotic were involved. Transcriptomic analysis also showed that the mutants did not present changes in the expression level of putative alternative peptidoglycan biosynthesis pathway genes neither any related enzyme. Finally, the mutants did not present an increased PEP concentration that might compete with fosfomycin for its binding to MurA. Based on these results, we describe a completely novel mechanism of antibiotic resistance based on the remodeling of S. maltophilia metabolism.
2020-05-11 | GSE141276 | GEO
Project description:MCR-1 in vivo acquisition in carbapenemase-producing E. coli
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Project description:The antibiotic fosfomycin is widely recognized for treatment of lower urinary tract infections caused by Escherichia coli and lately gained importance as a therapeutic option to combat multidrug resistant bacteria. Still, resistance to fosfomycin frequently develops through mutations reducing its uptake. Whereas the inner membrane transport of fosfomycin has been extensively studied in E. coli, its outer membrane (OM) transport remains insufficiently understood. While evaluating minimal inhibitory concentrations in OM porin-deficient mutants, we observed that the E. coli ΔompCΔompF strain is five times more resistant to fosfomycin than the wild type and the respective single mutants. Continuous monitoring of cell lysis of porin-deficient strains in response to fosfomycin additionally indicated the relevance of LamB. Furthermore, the physiological relevance of OmpF, OmpC and LamB for fosfomycin uptake was confirmed by electrophysiological and transcriptional analysis. This study expands the knowledge of how fosfomycin crosses the OM of E. coli.
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Project description:Recent studies have suggested that elevated expression of aldoketoreductase (AKR) 1C1 or 1C2 in tumour cells is associated with increased resistance to DNA damaging agents such as cisplatin and doxorubicin. However, it has not been shown whether selection of tumour cells for resistance to DNA-damaging anthracyclines actually results in increased expression of AKRs and increased conversion of anthracyclines to 10-fold less toxic 13-hydroxy metabolites. It is also unclear whether the induction of aldokeoreductases is temporally correlated with the onset of anthracycline resistance and whether there is a direct relationship between the level of AKR expression or activity and the magnitude of drug resistance. Through microarray profiling of MCF-7 breast cancer cells selected for progressive resistance to doxorubicin or epirubicin, we have identified several genes whose expression has been correlated with both the onset and magnitude of drug resistance, including a “1C” AKR. AKR 1C overexpression was verified by quantitative PCR. Also associated with the onset of anthracycline resistance were genes involved in drug transport (ABCB1), cell signaling and transcription (RDC1, CXCR4), cell proliferation or apoptosis (BMP7, CAV1), ROS protection (TXNRD1, MT2A), and structural or immune system proteins (IFI30, STMN1). Consistent with the role of AKRs in anthracycline resistance, doxorubicin- and epirubicin-resistant breast tumour cells exhibited 2.2-fold and 6.1-fold higher levels of the 13-hydroxy metabolite of doxorubicin (doxorubicinol) than wildtype MCF-7 cells. In addition, an inhibitor of AKR 1C2 (5- cholanic acid) almost completely restored sensitivity to doxorubicin in Abcb1-deficient doxorubicin-resistant cells, while having no effect on Abcb1-expressing epirubicin-resistant cells. Taken together, our findings strongly suggest the involvement of multiple genes in the acquisition of anthracycline resistance in breast tumor cells---in particular redox genes such as the 1C AKRs. Keywords: Drug resistance of breast cancer cells In order to identify genes whose expression strongly correlates with the acquisition or magnitude of drug resistance or are temporally related with the acquisition of resistance, we selected MCF-7 breast tumor cells for survival in increasing concentrations (doses) of doxorubicin or epirubicin. Panels of cells exhibiting progressive resistance to either doxorubicin (MCF-7DOX-2) or epirubicin (MCF-7EPI) were obtained. Cells were also “selected” in the absence of drug at each step during selection to serve as co-cultured control (MCF-7CC) cells. In this study, we have used cDNA microarray analysis of these cell lines to identify a variety of “redox” genes whose expression can be correlated with the acquisition or magnitude of drug resistance in MCF-7DOX-2 and MCF-7EPI cells, including a “1C” aldoketoreductase (AKR).
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Project description:An important, but rarely performed, test of Koch’s molecular postulates involves evaluating the capacity of candidate virulence genes to confer pathogenicity in otherwise non-virulent species. Unbiased genomic surveys of avirulent natural isolates might reveal rare variants possessing specific virulence features, which might prove useful in testing their functional sufficiency. Using a custom pan-genome array, we analyzed a panel of avirulent Burkholderia thailandensis (Bt) isolates related to Burkholderia pseudomallei (Bp), the causative agent of the often fatal human and animal disease melioidosis. We report the discovery of variant Bt isolates exhibiting isolated acquisition of a capsular polysaccharide biosynthesis gene cluster (BpCPS), long regarded as an critical species-specific virulence factor essential for Bp mammalian virulence. BpCPS-expressing Bt strains exhibited certain pathogen-related phenotypes including resistance to human complement binding, but did not exhibit enhanced virulence when assessed in two different in vivo animal infection models. Phylogenetic analysis revealed that the BpCPS-expressing Bt strains likely reside within an evolutionary subgroup distinct from the majority of previously-described Bt strains. Our findings suggest that BpCPS acquisition alone is unlikely to fully explain the ability of Bp to colonize humans and animals, highlighting the importance of other collaborating factors in the pathogenesis of mammalian melioidosis. Genomic DNA of several Bt strains were hybridized against a common reference strain (Bt E264), to see gain/loss
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Project description:One of the hallmarks of Pseudomonas aeruginosa cystic fibrosis (CF) infection is very high-cell-density (HCD) replication in the lung, allowing this bacterium to induce virulence controlled by HCD quorum-sensing systems. However, the nutrient sources sustaining HCD replication in this chronic infection is largely unknown. Hence, understanding the nutrient factors contributing to HCD in the CF lung will yield new insights into the 'metabolic pathogenicity' and potential treatment of CF infections caused by P. aeruginosa. Herein, we performed microarray studies of P. aeruginosa directly isolated from the CF lung to demonstrate its metabolic capability and virulence in vivo. Our in vivo microarray data, confirmed by real-time reverse-transcription-PCR, indicated P. aeruginosa expressed several genes for virulence, drug-resistance, and utilization of multiple nutrient sources (lung surfactant lipids and amino acids) contributing to HCD replication. The data also indicates deregulation of several pathways, suggesting in vivo evolution by deregulation of a large portion of the transcriptome during chronic CF infection. To our knowledge, this is the first in vivo transcriptome of P. aeruginosa in a natural CF infection, and it indicates several important aspects of pathogenesis, drug-resistance, and nutrient-utilization never before observed in vivo. Keywords: in vivo gene induction
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