Biology subjects

Hohnen, L.

Publications and source records attributed to Hohnen, L..

2 recordsLinked to original sources

bioRxiv2025

Identification of small molecule inhibitors of Trypanosoma PEX15--PEX6 interaction

Trypanosomatid parasites that cause life threatening tropical diseases harbor specialized essential organelles, called glycosomes. Like other peroxisome-related organelles, the biogenesis of glycosomes is mediated by proteins known as peroxins (PEX). A cascade of PEX protein-protein interactions (PPIs) is essential for glycosome function and parasite survival. Accordingly, small molecule inhibitors of PEX proteins that disrupt glycosomal matrix or membrane protein import have been reported as potential therapies for trypanosomiasis. We recently identified the long sought-after Trypanosoma PEX15 (TbPEX15), which anchors the PEX1-PEX6 complex to the glycosomal membrane for recycling of the receptor PEX5. Defects in this process cause PEX5 degradation, mislocalization of glycosomal matrix proteins and parasite death. In this study, we targeted the interaction between TbPEX6 and TbPEX15. Recombinant TbPEX6 and TbPEX15 were purified, and their interaction was confirmed by in vitro pull-down assays and size exclusion chromatography. Furthermore, we established an AlphaScreen-based method to identify small molecule inhibitors of this PPI. Screening of a drug-repurposing library identified two inhibitors with trypanocidal activity against T. brucei in vitro and the amastigote stage of T. cruzi. Given its essentiality and low sequence similarity to its human homolog, parasite PEX15 and its interaction with PEX6 represent promising targets for the development of new therapies against trypanosomatid infections.

microbiology↗

bioRxiv2023

High confidence glycosomal membrane protein inventory unveils trypanosomal Peroxin PEX15

Infections by trypanosomatid parasites cause Chagas disease, Human African Trypanosomiasis, and Leishmaniasis, affecting over 12 million people worldwide. Glycosomes, the unique peroxisome-related organelles of trypanosomes are essential for their survival, and hence their metabolic functions and biogenesis mediated by peroxins (PEX) are suitable as drug targets. Here we report on a comprehensive protein inventory of glycosomal membranes through advanced subcellular membrane protein profiling employing quantitative mass spectrometry. Our quantitative analysis resulted in the identification of 28 novel high confidence glycosomal membrane proteins. Our in-depth protein inventory of glycosomal membranes serves as an important resource for characterizing glycosome biology and drug development. We validated four so far unknown glycosomal membrane proteins, including two tail-anchored (TA) proteins, a homolog of human peroxisomal PXMP4, and a Macrodomain-containing protein. Using a structure-based approach, we identified one of the TA proteins as the long-sought Trypanosoma PEX15. Despite its low sequence similarity, Trypanosoma PEX15 exhibits structural and topological similarities with its yeast (Pex15) and human counterparts (PEX26). We show that PEX15 is an essential integral glycosomal membrane protein that interacts with PEX6. Accordingly, RNAi knockdown of PEX15 in bloodstream form trypanosomes demonstrates that it is essential for glycosome biogenesis and parasite survival. Considering the low degree of conservation with its human counterpart, PEX15 is a promising molecular target for drug development.

cell biology↗