# The 26 S proteasome in Entamoeba histolytica: divergence of the substrate binding pockets from host proteasomes

## TL;DR

This study compares proteasomes in the parasite Entamoeba histolytica with human proteasomes to identify differences that could help design selective drugs.

## Contribution

The study reveals structural and functional differences in substrate binding pockets of E. histolytica proteasomes that could guide selective inhibitor development.

## Key findings

- E. histolytica proteasomes show distinct substrate binding preferences in S1 and S3 pockets compared to host proteasomes.
- Amoebic proteasomes are less sensitive to MG132 inhibition than human proteasomes.
- Computational models suggest a β4-β5 binding pocket in E. histolytica similar to Leishmania tarentolae, with potential for selective inhibitors.

## Abstract

Proteasomes are conserved proteases crucial for proteostasis in eukaryotes and are promising drug targets for protozoan parasites. Yet, the proteasomes of Entamoeba histolytica remain understudied. The study’s objective was to analyse the differences in the substrate binding pockets of amoeba proteasomes from those of host, and computational modelling of β5 catalytic subunit, with the goal of finding selective inhibitors.

Comparative sequence analysis revealed differences in substrate binding sites of E. histolytica proteasomes, especially in the S1 and S3 pockets of the catalytic beta subunits, implying differences in substrate preference and susceptibility to inhibitors from host proteasomes. This was strongly supported by significantly lower sensitivity to MG132 mediated inhibition of amoebic proteasome β5 subunit’s chymotryptic activity compared to human proteasomes, also reflected in lower sensitivity of E. histolytica to MG132 for inhibition of proliferation. Computational models of β4 and β5 subunits, and a docked β4-β5 model revealed a binding pocket between β4-β5, similar to that of Leishmania tarentolae. Selective inhibitors for visceral leishmaniasis, LXE408 and compound 8, docked well to this pocket. This functional and sequence-based analysis predicts differences between amoebic and host proteasomes that can be utilized to develop rationally designed, selective inhibitors against E. histolytica.

The online version contains supplementary material available at 10.1186/s13104-024-06848-y.