Resolving the Peroxisome Importer Structure by Mass Spectrometry and Structural Prediction Methodologies
2School of Computer Science and Engineering, The Hebrew University of Jerusalem, Israel
Peroxisomes are organelles found in all eukaryotic cells, with diverse functions according to the cell type and metabolic conditions. Peroxisomes play a key role in cell metabolism and homeostasis and have an emerging role in inflammation and the immune response. Many of the peroxisomal proteins are called peroxins (PEX proteins). Mutations in almost all PEX proteins cause Zellweger syndrome with severe metabolic and neurological abnormalities. However, the structure of some of the most important peroxisomal protein complexes, which is key to understanding their function, is not known. Specifically, the docking complex, which in humans comprises mainly PEX13 and PEX14, enables soluble receptors, PEX5 and PEX7, to import cytosolic protein cargo into the peroxisomal lumen. Here, we employed an integrative modelling approach to determine previously unknown structural features of the import machinery. Mass spectrometry-based proteomics with cross-linking experimental approaches, were used to refine the 3D predicting models assisted by AlphaFold. We argue that this approach, based on the overexpression of key PEX proteins, will shed light on the mechanism by which proteins are imported and the effect of pathological mutations on the import process.