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P-glycoprotein genes of Entamoeba histolytica
S Descoteaux1, P S Shen, P Ayala
1Department of Tropical Public Health, Harvard School of Public Health, Boston, MA.
Abstract:
Six different P-glycoprotein gene segments were identified from an emetine-resistant E. histolytica mutant, which overexpresses mRNAs homologous to segments of the human mdr1 (P-glycoprotein) gene. The open reading frames of two completely sequenced genes EhPgp1 and EhPgp2 were 1,302 and 1,310 amino acids long, respectively, and showed a 67% positional identity with each other and 41 and 40% positional identities, respectively, with human mdr1 gene. Within each ameba P-glycoprotein were the ATP-binding sites found twice in eukaryotic P-glycoproteins and once in prokaryotic transport proteins. A phylogenetic tree showed that Entamoeba P-glycoproteins are more related to the human and mouse P-glycoproteins than to the Plasmodium and Leishmania P-glycoproteins. In addition, there were two P-glycoprotein pseudogenes, each with a frame shift and stop codons in identical places within the amino ATP-binding site.
Insights
Researchers identified six P-glycoprotein gene segments in E. histolytica, revealing similarities to human multidrug resistance genes. These findings shed light on drug resistance mechanisms in parasitic infections.
Area of Science:
- Molecular Biology
- Parasitology
- Genetics
Background:
- Emetine resistance in *E. histolytica* is linked to P-glycoprotein (Pgp) gene expression.
- Human multidrug resistance (MDR) genes, like *mdr1*, are well-characterized Pgps involved in drug efflux.
Purpose of the Study:
- To identify and characterize P-glycoprotein genes in an emetine-resistant *E. histolytica* mutant.
- To investigate the evolutionary relationship of *E. histolytica* Pgps with those from other organisms.
Main Methods:
- Gene sequencing and analysis of *E. histolytica* mutants.
- Bioinformatic analysis including sequence alignment and phylogenetic tree construction.
Main Results:
- Six P-glycoprotein gene segments were identified, with two full-length genes, *EhPgp1* and *EhPgp2*, sequenced.
- *EhPgp1* and *EhPgp2* share 67% positional identity and show 40-41% identity to human MDR1.
- Phylogenetic analysis indicates *E. histolytica* Pgps are more closely related to mammalian Pgps than to those in *Plasmodium* or *Leishmania*.
- Two P-glycoprotein pseudogenes with frame shifts in the ATP-binding site were also identified.
Conclusions:
- *E. histolytica* possesses functional P-glycoprotein genes homologous to human MDR genes, potentially contributing to drug resistance.
- The identified Pgps contain conserved ATP-binding sites, crucial for transporter function.
- Evolutionary analysis suggests a conserved Pgp lineage across eukaryotes, with distinct divergences.