Primary sequences of two P-glycoprotein genes of Entamoeba histolytica

Descoteaux, Steven; Ayala, Patricia; Orozco, Esther; Samuelson, John

doi:10.1016/0166-6851(92)90112-w

Cited by 71 publications

(28 citation statements)

References 30 publications

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“…T h i s fragment w a s used to isolate t w o identical genomic DNA a n d cDNA clones, indicating the absence of introns in the Ehtbp gene, as also reported for other E. histolytica genes (Descoteaux et al, 1992;Sanchez et al, 1994). T 702 bp ORF encoding a predicted 234aa (26 kDa) polypeptide with a pI of 9-27.…”

Section: Resultsmentioning

confidence: 99%

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The TATA-box binding protein of Entamoeba histolytica: cloning of the gene and location of the protein by immunofluorescence and confocal microscopy

Luna-Arias

Hernández‐Rivas

Dios-Bravo³

et al. 1999

Microbiology

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A 309 bp DNA fragment from Entamoeba histolytica was amplified by PCR using primers derived from the Acanthamoeba castellanii consensus TATA-box binding protein amino acid sequence. The amplified fragment was used to isolate cDNA and genomic DNA clones containing an ORF encoding the complete E. histolytica TATA-box binding protein (Ehtbp, 702 bp, 234 aa, molecular mass 26 kDa). The EhTBP functional domain showed 55% sequence identity to that of Homo sapiens, 54% to A. castellanii and 37% to Plasmodium falciparum TBPs. In Southern blot experiments w e detected a single Ehtbp band, which was transcribed as a 1.3 kb mRNA containing a 420 nt 5' untranslated region. However, the probe hybridized with the 0.8 and 1.5 Mb chromosomes, suggesting that this sequence is diploid. In situ PCR assays showed two signals in 95% of trophozoites, one located in the nucleus and another in EhkO, the novel DNA-containing organelle recently reported. The recombinant Em histolytica TATA-box binding protein was expressed in Escherichia coli. Antibodies against it recognized two proteins of 26 and 29 kDa in E. histolytica nuclear extracts. Confocal microscopy immunofluorescence analysis located the protein in both the nucleus and EhkO.~

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Section: Resultsmentioning

confidence: 99%

“…histolytica cDNA and genomic DNA libraries constructed in-ILZAPII (Descoteaux et al, 1992;Sanchez et al, 1994). Both strands of cDNA and DNA clones containing the full length…”

Section: Tata-box Binding Protein Of Entamoeba Histofyticamentioning

confidence: 99%

The TATA-box binding protein of Entamoeba histolytica: cloning of the gene and location of the protein by immunofluorescence and confocal microscopy

Luna-Arias

Hernández‐Rivas

Dios-Bravo³

et al. 1999

Microbiology

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“…To our knowledge, this is the first report of the identification of a polymorphic nonsense mutation in an Entamoeba gene, although pseudogenes for Entamoeba P glycoproteins and Entamoeba dispar cysteine proteinase 5 have been observed (11,41). We were able to identify just eight other genes with nonsense mutations in genome project strain HM-1:IMSS of Entamoeba (our unpublished data).…”

Section: Fig 2 Recombinant Expression Of Entamoeba and Trichomonasmentioning

confidence: 99%

Giardia , Entamoeba , and Trichomonas Enzymes Activate Metronidazole (Nitroreductases) and Inactivate Metronidazole (Nitroimidazole Reductases)

Pal

Banerjee

Cui

et al. 2009

Antimicrob Agents Chemother

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Infections with Giardia lamblia, Entamoeba histolytica, and Trichomonas vaginalis, which cause diarrhea, dysentery, and vaginitis, respectively, are each treated with metronidazole. Here we show that Giardia, Entamoeba, and Trichomonas have oxygen-insensitive nitroreductase (ntr) genes which are homologous to those genes that have nonsense mutations in metronidazole-resistant Helicobacter pylori isolates. Entamoeba and Trichomonas also have nim genes which are homologous to those genes expressed in metronidazole-resistant Bacteroides fragilis isolates. Recombinant Giardia, Entamoeba, and Trichomonas nitroreductases used NADH rather than the NADPH used by Helicobacter, and two recombinant Entamoeba nitroreductases increased the metronidazole sensitivity of transformed Escherichia coli strains. Conversely, the recombinant nitroimidazole reductases (NIMs) of Entamoeba and Trichmonas conferred very strong metronidazole resistance to transformed bacteria. The Ehntr1 gene of the genome project HM-1:IMSS strain of Entamoeba histolytica had a nonsense mutation, and the same nonsense mutation was present in 3 of 22 clinical isolates of Entamoeba. While ntr and nim mRNAs were variably expressed by cultured Entamoeba and Trichomonas isolates, there was no relationship to metronidazole sensitivity. We conclude that microaerophilic protists have bacterium-like enzymes capable of activating metronidazole (nitroreductases) and inactivating metronidazole (NIMs). While Entamoeba and Trichomonas displayed some of the changes (nonsense mutations and gene overexpression) associated with metronidazole resistance in bacteria, these changes did not confer metronidazole resistance to the microaerophilic protists examined here.

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“…selected in the laboratory take up less drug than susceptible parasites do, which is consistent with the action of a P-glycoprotein pump (5). The particular mdr (P-glycoprotein) gene amplified in the mutant clone C2 amebae, one of multiple mdr genes present in E. histolytica (10,29), may not pump out metronidazole. Alternatively, metronidazole resistance may be associated with a particular mutation in the overexpressed ameba mdr gene, because single amino acid substitutions in the overexpressed P-glycoproteins of MDR tumor cells change both the efficacy and specificity of drug resistance (9,17).…”

mentioning

confidence: 99%

Susceptibility of an emetine-resistant mutant of Entamoeba histolytica to multiple drugs and to channel blockers

Samuelson¹,

Burke²,

Courval³

1992

Antimicrob Agents Chemother

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Previously a cloned emetine-resistant mutant of the protozoal parasite Entamoeba histolyica was shown to overexpress a gene for an ameba homolog of the mammalian P-glycoprotein, a plasma membrane pump that removes hydrophobic drugs from multidrug-resistant tumor cells. Three sets of experiments were performed to better characterize the multidrug-resistant phenotype of the emetine-resistant amebae. First, the emetine resistance of the mutant amebae was reversed by concentrations of calcium and sodium channel blockers effective in reversing drug resistance by multidrug-resistant tumor cells, but it was reversed only in the presence of very high concentrations of the tricyclic antidepressants. Second, the mutant amebae showed cross-resistance to antiamebic drugs used to treat luminal infection (iodoquinol and diloxanide) but were not cross-resistant to dmrgs used to treat invasive disease (chloroquine and metronidazole). Third, when amebae were loaded with radiolabeled emetine, the mutant parasites released the drug at -1.6 times the rate of the wild-type organisms. We conclude that the emetine-resistant E. histolytica parasites have some but not all the features of the multidrug-resistant phenotype.Entamoeba histolytica is a protozoal parasite that infects

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Primary sequences of two P-glycoprotein genes of Entamoeba histolytica

Cited by 71 publications

References 30 publications

The TATA-box binding protein of Entamoeba histolytica: cloning of the gene and location of the protein by immunofluorescence and confocal microscopy

The TATA-box binding protein of Entamoeba histolytica: cloning of the gene and location of the protein by immunofluorescence and confocal microscopy

Giardia , Entamoeba , and Trichomonas Enzymes Activate Metronidazole (Nitroreductases) and Inactivate Metronidazole (Nitroimidazole Reductases)

Susceptibility of an emetine-resistant mutant of Entamoeba histolytica to multiple drugs and to channel blockers

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