Transcriptional and functional analysis of trifluoromethionine resistance in Entamoeba histolytica
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ABSTRACT: Previously, we have shown that in Entamoeba histolytica, methionine γ-lyase (EhMGL) downregulation results in trifluoromethionine resistance. The transcriptional response, however, of this parasite to the drug is not known. In this study, we used microarray analysis to determine if additional genes are involved. The expression profile of 9,230 genes in wild type and trifluoromethionine resistant strains was compared. Episomal overexpression of EhBspA1 was performed to verify its role in trifluoromethionine resistance. The transcriptomes of trifluoromethionine resistant strain cultured with or without trifluoromethionine, EhMGL-gene silenced strain, metronidazole resistant strain, and wild type strain under cysteine-deprived conditions were compared to determine the specificity of the changes observed in trifluoromethionine resistant strain.
Project description:In vitro studies have described metronidazole (MTZ) resistance and the potential mechanisms involved. Costs to fitness and adaptive responses associated with resistance, however, have not been investigated. In this study we generated an HM-1-derived strain resistant to 12 µM MTZ (MTZR). We examined its phenotypic and transcriptional profile to determine the consequences and mRNA level changes associated with MTZ resistance. The expression profile of 9,230 genes in wild-type and metronidazole-resistant strains was compared. Transcriptome analysis revealed 142 differentially expressed genes in MTZR. In contrast to other MTZ-resistant parasites, MTZR did not down-regulate pyruvate:ferredoxin oxidoreductase, but showed increased expression of genes for a hypothetical protein (HP1) and several iron-sulfur flavoproteins, and the downregulation of genes for leucin-rich proteins. Overexpression of HP1-HA did not confer MTZR level of resistance, but provided a slight advantage in cell survival. Fisher's exact test showed 24 significantly enriched GO terms in MTZR, and a 3-way comparison of modulated genes with MTZR cultured without MTZ and HM-1 cultured with MTZ showed that 88 genes were specific to MTZR. Wild-type and the MTZ-resistant strain MTZR were cultured either in the presence or absence of MTZ. 2 biological replicates per strain/condition.
Project description:Phenotypic and transcriptional profiling in Entamoeba histolytica reveal costs to fitness and adaptive responses associated with metronidazole resistance
Project description:Up until now, the existence of Dnmt2-mediated DNA methylation has mostly been supported by focal analyses in organisms that contain Dnmt2, but no Dnmt1 or Dnmt3 DNA methyltransferase. In these organisms, several independent studies have also provided support for a biologically important function of Dnmt2-dependent DNA methylation. For example, Dnmt2-dependent methylation in Entamoeba histolytica, the causative agent of amebic dysentery, has been connected to the parasite s virulence. However, global DNA methylation levels in Entamoeba have been found to be very low. In addition, no specific features, such as CpG-specificity and specificity for certain genetic subcompartments have been described. This distinguishes Dnmt2-dependent methylation patterns from all other known methylomes and has raised questions about the validity of the underlying results. We have used whole-genome bisulfite sequencing for an unbiased characterization of the Entamoeba histolytica methylome at single-base resolution in a E.histolytica strain HM-1:IMSS devoid of significant level of EhDnmt2 (Ehmeth) expression.