Competitive Microtubule Binding of PEX14 Coordinates Peroxisomal Protein Import and Motility

Human PEX14 plays a dual role as docking protein in peroxisomal protein import and as peroxisomal anchor for microtubules (MT), which relates to peroxisome motility. For docking, the conserved N-terminal domain of PEX14(PEX14-NTD) binds amphipathic alpha-helical ligands, typically comprising one or two aromatic residues, of which human PEX5 possesses eight. Here, we show that the PEX14-NTD also binds to microtubular filaments in vitro with a dissociation constant in nanomolar range. PEX14 interacts with two motifs in the C-terminal region of human beta-tubulin. At least one of the binding motifs is in spatial proximity to the binding site of microtubules (MT) for kinesin. Both PEX14 and kinesin can bind to MT simultaneously. Notably, binding of PEX14 to tubulin can be prevented by its association with PEX5. The data suggest that PEX5 competes peroxisome anchoring to MT by occupying the beta-tubulin-binding site of PEX14. The competitive correlation of matrix protein import and motility may facilitate the homogeneous dispersion of peroxisomes in mammalian cells. (C) 2020 Elsevier Ltd. All rights reserved.

Automated summary

Human PEX14 acts as a dual role in peroxisomal protein import and microtubule anchoring, with its N-terminal domain binding both protein ligands and microtubular filaments. PEX14 interacts with beta-tubulin in spatial proximity to kinesin-binding site on microtubules, and its binding to tubulin can be blocked by PEX5, suggesting a competitive correlation between peroxisome anchoring and motility for homogeneous dispersion in mammalian cells.