College of Life and Environmental Sciences, Biosciences, University of Exeter, Exeter, UK.
Institute of Biology II, Biochemistry and Functional Proteomics, Faculty of Biology, University of Freiburg, Freiburg, Germany.
J Cell Biol. 2022 Mar 7;221(3). doi: 10.1083/jcb.202003143. Epub 2022 Jan 12.
Peroxisomes and the endoplasmic reticulum (ER) cooperate in cellular lipid metabolism. They form membrane contacts through interaction of the peroxisomal membrane protein ACBD5 (acyl-coenzyme A-binding domain protein 5) and the ER-resident protein VAPB (vesicle-associated membrane protein-associated protein B). ACBD5 binds to the major sperm protein domain of VAPB via its FFAT-like (two phenylalanines [FF] in an acidic tract) motif. However, molecular mechanisms, which regulate formation of these membrane contact sites, are unknown. Here, we reveal that peroxisome-ER associations via the ACBD5-VAPB tether are regulated by phosphorylation. We show that ACBD5-VAPB binding is phosphatase-sensitive and identify phosphorylation sites in the flanking regions and core of the FFAT-like motif, which alter interaction with VAPB-and thus peroxisome-ER contact sites-differently. Moreover, we demonstrate that GSK3β (glycogen synthase kinase-3 β) regulates this interaction. Our findings reveal for the first time a molecular mechanism for the regulation of peroxisome-ER contacts in mammalian cells and expand the current model of FFAT motifs and VAP interaction.
过氧化物酶体和内质网（ER）在细胞脂质代谢中合作。它们通过过氧化物酶体膜蛋白 ACBD5（酰基辅酶 A 结合域蛋白 5）和 ER 驻留蛋白 VAPB（囊泡相关膜蛋白相关蛋白 B）的相互作用形成膜接触。ACBD5 通过其 FFAT 样（酸性片段中的两个苯丙氨酸[FF]）基序与 VAPB 的主要精子蛋白结构域结合。然而，调节这些膜接触位点形成的分子机制尚不清楚。在这里，我们揭示了通过 ACBD5-VAPB 系绳的过氧化物酶体-ER 关联受磷酸化调节。我们表明 ACBD5-VAPB 结合对磷酸酶敏感，并鉴定出 FFAT 样基序侧翼区域和核心中的磷酸化位点，这些位点改变了与 VAPB 的相互作用，从而改变了过氧化物酶体-ER 接触位点的不同。此外，我们证明 GSK3β（糖原合酶激酶 3β）调节这种相互作用。我们的发现首次揭示了调节哺乳动物细胞过氧化物酶体-ER 接触的分子机制，并扩展了 FFAT 基序和 VAP 相互作用的现有模型。
