The peroxisome counteracts oxidative stresses by suppressing catalase import via Pex14 phosphorylation

Okumoto, Kanji; El Shermely, Mahmoud; Natsui, Masanao; Kosako, Hidetaka; Natsuyama, Ryuichi; Marutani, Toshihiro; Fujiki, Yukio

Most of peroxisomal matrix proteins including a hydrogen peroxide (H(2)O(2))-decomposing enzyme, catalase, are imported in a peroxisome-targeting signal type-1 (PTS1)-dependent manner. However, little is known about regulation of the membrane-bound protein import machinery. Here, we report that Pex14, a central component of the protein translocation complex in peroxisomal membrane, is phosphorylated in response to oxidative stresses such as H(2)O(2) in mammalian cells. The H(2)O(2)-induced phosphorylation of Pex14 at Ser232 suppresses peroxisomal import of catalase in vivo and selectively impairs in vitro the interaction of catalase with the Pex14-Pex5 complex. A phosphomimetic mutant Pex14-S232D elevates the level of cytosolic catalase, but not canonical PTS1-proteins, conferring higher cell resistance to H(2)O(2). We thus suggest that the H(2)O(2)-induced phosphorylation of Pex14 spatiotemporally regulates peroxisomal import of catalase, functioning in counteracting action against oxidative stress by the increase of cytosolic catalase.