A Novel Peroxin is Required for Mitochondrial Morphology: Implications for Resolving a New Peroxisome‐Mitochondrial Contact Site

Abstract

Peroxisomes are dynamic and ubiquitous organelles that house many metabolic pathways and interact with other organelles such as the endoplasmic reticulum, lipid droplets, and mitochondria. One mechanism for organelle interaction is through membrane contact sites. While contact sites between multiple organelles have been identified, little is known about the proteins that serve as molecular tethers in such sites. We study organelle dynamics using peroxisome‐like organelles called glycosomes in the early diverging organism Trypanosoma brucei and have identified a novel peroxin (protein involved in peroxisome biogenesis) that is essential for mitochondrial morphology. Silencing this protein leads to a significant growth defect and swollen mitochondria. Multiple mitochondrial membrane transport channels have been identified in immunoprecipitation studies. Based on these findings, we hypothesize that this protein that we have named a putative peroxisome‐mitochondrial contact protein (PPMCP), localizes to glycosomes and mitochondria at contact points, which facilitate the transfer of metabolites between the two organelles. Disruption of this connection results in “leaky” mitochondria and cell death. Current work is focused on resolving the metabolic defects in PPMCP‐deficient cells and identifying additional molecular components of these contact sites. This work forwards our understanding of how contact sites are established and the role they play in interorganelle communication.