Abstract
The correct topogenesis of peroxisomal membrane proteins is a crucial step for the formation of functioning peroxisomes. Although this process has been widely studied, the exact mechanism with which it occurs has not yet been fully characterized. Nevertheless, it is generally accepted that peroxisomes employ three proteins – Pex3, Pex19 and Pex16 in mammals – for the insertion of peroxisomal membrane proteins into the peroxisomal membrane. Structural biology approaches have been utilized for the elucidation of the mechanistic questions of peroxisome biogenesis, mainly by providing information on the architecture of the proteins significant for this process. This review aims to summarize, compare and put into perspective the structural knowledge that has been generated mainly for Pex3 and Pex19 and their interaction partners in recent years. This article is part of a Special Issue entitled: Peroxisomes edited by Ralf Erdmann.
Highlights
Peroxisomes are cell organelles found in virtually all multi-cellular organisms and comprise a separate cellular compartment whose main functions include the sequestration of metabolic processes that would otherwise be toxic to the cell, as well as the biosynthesis of several essential lipids [1]
It is generally accepted that peroxisomes employ three proteins – Peroxisomal biogenesis docking factors 3 (Pex3), Peroxisomal biogenesis factor 19 (Pex19) and Pex16 in mammals – for the insertion of peroxisomal membrane proteins into the peroxisomal membrane
This review aims to summarize, compare and put into perspective the structural knowledge that has been generated mainly for Pex3 and Pex19 and their interaction partners in recent years
Summary
Peroxisomes are cell organelles found in virtually all multi-cellular organisms and comprise a separate cellular compartment whose main functions include the sequestration of metabolic processes that would otherwise be toxic to the cell, as well as the biosynthesis of several essential lipids [1]. The impact of farnesylation for Pex function, as judged from in vivo experiments in yeast and mammalian cell lines, with predicted amphipathic helical properties has been recently implicated in Pex insertion into the peroxisomal membrane by a release mechanism from Pex19 [39] This segment has been suggested to compete with the mPTS-binding helix from the Pex C-terminal domain [51]. Pex has the ability to actively bind newly-synthesized PMPs as shown by a study of Pex with an engineered nuclear localization signal that resulted in enrichment of PMPs in the nucleus [40] This argues in favor of a stable and constitutive interaction of Pex and PMPs. Recent data indicate that the balance of hydrophobic and charged residues in the mPTS of tailanchored proteins, a PMP subclass, are critical to determine competitive binding to Pex and endoplasmic reticulum associated cytosolic ATPase TRC40 (Get in yeast) [38]. Inp has been shown to regulate peroxisome motility, as a requirement for peroxisomal proliferation, and abundance
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