Entamoeba histolytica EHD1 Is Involved in Mitosome-Endosome Contact

Area of Science:

• Cell Biology
• Parasitology
• Organelle Biology

Background:

• Membrane contact sites (MCSs) facilitate communication between organelles, but their role in mitochondrion-related organelles (MROs) of anaerobic parasites is understudied.
• Entamoeba histolytica, a parasitic protozoan causing amoebiasis, possesses a mitosome, a type of MRO crucial for its survival and virulence.

Purpose of the Study:

• To investigate potential MCSs involving the mitosome in Entamoeba histolytica.
• To identify proteins mediating interactions between the mitosome and other cellular compartments.

Main Methods:

• Bioinformatic and cell-biological analyses to identify and characterize Entamoeba-specific transmembrane mitosomal proteins (ETMPs).
• Immunoprecipitation to identify interacting partners of ETMP1.
• Expression of tagged proteins (HA-EHD1, GFP-EHD1) in E. histolytica for immunofluorescence and live imaging.
• Immunoelectron microscopy (IEM) and carbonate fractionation to confirm protein localization and membrane association.
• In vitro ATPase activity assays using recombinant proteins.

Main Results:

• The mitosomal protein ETMP1 interacts with EH domain-containing protein 1 (EHD1).
• EHD1 localizes to an unprecedented membrane contact site between the mitosome and endosomes.
• EHD1 is involved in early endosome formation and exhibits ATPase activity.

Conclusions:

• A novel mitosome-endosome membrane contact site (MCS) has been identified in Entamoeba histolytica, mediated by the ETMP1-EHD1 interaction.
• This discovery highlights that MROs, despite their reduced nature, participate in interorganellar communication, similar to conventional mitochondria.
• The ETMP1-EHD1 tethered MCS may regulate processes such as lipid/ion transport, organelle fission, and quality control in E. histolytica.