Development of a negative selectable marker for Entamoeba histolytica

Area of Science:

• Parasitology
• Molecular Biology
• Genetics

Background:

• Entamoeba histolytica causes amebiasis, affecting a significant portion of the global population.
• Current molecular techniques for gene expression studies rely on plasmids, limiting genetic manipulation capabilities.
• Studying Entamoeba virulence factors is hampered by the lack of genomic integration methods and challenges in eliminating episomal DNA.

Purpose of the Study:

• To develop a novel negative selection system for Entamoeba histolytica.
• To facilitate the identification of true genomic integration events in transfected parasites.
• To enable advanced reverse genetics studies in Entamoeba histolytica.

Main Methods:

• Development of a transgenic system expressing a yeast cytosine deaminase and uracil phosphoribosyl transferase chimera (FCU1).
• Application of the prodrug 5-fluorocytosine (5-FC) for negative selection.
• Comparison of drug sensitivity between FCU1-expressing and control Entamoeba histolytica strains.

Main Results:

• The FCU1 enzyme converts non-toxic 5-FC into toxic compounds.
• Entamoeba histolytica lines expressing FCU1 showed a 30-fold increased sensitivity to 5-FC compared to controls.
• This system effectively selects against cells with episomal DNA, aiding in identifying genomic integration.

Conclusions:

• The developed FCU1-based negative selection system is effective in Entamoeba histolytica.
• This system overcomes challenges in identifying genomic integration events.
• It provides a valuable tool for advancing reverse genetics and understanding Entamoeba virulence factors.