Mitotic phosphorylation of Pex14p regulates peroxisomal import machinery

Abstract

Peroxisomal matrix proteins are imported into peroxisomes via membrane-bound docking/translocation machinery. One central component of this machinery is Pex14p, a peroxisomal membrane protein involved in the docking of Pex5p, the receptor for peroxisome targeting signal type 1 (PTS1). Studies in several yeast species have shown that Pex14p is phosphorylated in vivo, whereas no function has been assigned to Pex14p phosphorylation in yeast and mammalian cells. Here, we investigated peroxisomal protein import and its dynamics in mitotic mammalian cells. In mitotically arrested cells, Pex14p is phosphorylated at Ser-232, resulting in a lower import efficiency of catalase, but not the majority of proteins including canonical PTS1 proteins. Conformational change induced by the mitotic phosphorylation of Pex14p more likely increases homomeric interacting affinity and suppresses topological change of its N-terminal part, thereby giving rise to the retardation of Pex5p export in mitotic cells. Taken together, these data show that mitotic phosphorylation of Pex14p and consequent suppression of catalase import are a mechanism of protecting DNA upon nuclear envelope breakdown at mitosis.

Regulating peroxisome–ER contacts via the ACBD5-VAPB tether by FFAT motif phosphorylation and GSK3β

“…Many peroxisomal proteins, involved in various processes such as peroxisome biogenesis and protein import, are phosphorylated according to phospho-proteomics studies, but the biological function of this phosphorylation remains largely unknown in mammals ( Oeljeklaus et al, 2016 ). Phosphorylation of human PEX5, the shuttling import receptor for peroxisomal matrix proteins, has been shown to be implicated in pexophagy in response to reactive oxygen species ( Zhang et al, 2015 ), while phosphorylation of PEX14, a part of the peroxisomal import machinery, suppressed the import of catalase into peroxisomes under oxidative stress conditions and in mitotic cells ( Okumoto et al, 2020 ; Yamashita et al, 2020 ). Our novel findings on the regulation of the ACBD5-VAPB tether, and subsequent peroxisome–ER membrane contacts, represent another example for a physiologic role of phosphorylation of peroxisomal membrane proteins in mammals.…”

Post‐translational modifications of proteins associated with yeast peroxisome membrane: An essential mode of regulatory mechanism

“…Earlier studies have also identified Ser 266 and Ser 313 residues of S. cerevisiae Pex14 to be phosphorylated (Albuquerque et al, 2008). H 2 O 2 -induced phosphorylation of Pex14 at Ser 232 was reported in mammalian cells recently, and this PTM suppressed the peroxisomal import of catalase in mammalian mitotic cells (Okumoto et al, 2020;Yamashita et al, 2020).…”

Regulating peroxisome-ER contacts via the ACBD5-VAPB tether by FFAT motif phosphorylation and GSK3β

“…Phosphorylation of human PEX5, the shuttling import receptor for peroxisomal matrix proteins, has been shown to be implicated in pexophagy in response to ROS (Zhang et al, 2015). Phosphorylation of mammalian PEX14, a membrane protein that is part of the peroxisomal import machinery, suppressed the import of catalase into peroxisomes under oxidative stress conditions and in mitotic cells (Okumoto et al, 2020;Yamashita et al, 2020). Additionally, Pex14p phosphorylation in the yeast S. cerevisiae controls the import of Cit2p, the peroxisomal isoform of citrate synthase (Schummer et al, 2020).…”