Competitive Microtubule Binding of PEX14 Coordinates Peroxisomal Protein Import and Motility

Abstract

PEX14 functions as peroxisomal docking protein for the import receptor PEX5. 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 ß-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 ß-tubulin-binding site of PEX14. The competitive correlation of matrix protein import and motility may facilitate the homogeneous dispersion of peroxisomes in mammalian cells.

Recruitment of Peroxin14 to lipid droplets affects triglyceride storage in Drosophila

“…In 2019, Barros-Barbosa et al showed that rat PEX14 is an intrinsic membrane protein with an N-in C-out topology (Barros-Barbosa et al, 2019; Reuter et al, 2021). Myc-tagged N-and C-terminal truncations of Pex14 were tested for localization to LDs or peroxisomes in +Oleate cells (Figure 4G).…”

“…Pex3, Pex13, and Pex14 are all bilayer membrane spanning proteins inserted into PPVs, in a process that likely requires Pex19 (Götte et al, 1998; Pinto et al, 2006). When inserted into the peroxisome membrane, the Pex14 C-terminal domain faces the cytoplasm (Barros-Barbosa et al, 2019; Reuter et al, 2021). One possible model is that Pex14 at the LD surface is embedded within vesicles and the C-terminal of Pex14 interacts with an LD-resident protein, or that the C-terminal of Pex14 that can interact directly with the LD surface.…”