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The common phospholipid-binding activity of the N-terminal domains of PEX1 and VCP/p97

International Graduate School of Arts and Sciences, Yokohama City University, 1-7-29 Suehiro-cho, Tsurumi-ku, Yokohama, Kanagawa 230-0045, Japan.
FEBS Journal (Impact Factor: 3.99). 12/2006; 273(21):4959-71. DOI: 10.1111/j.1742-4658.2006.05494.x
Source: PubMed

ABSTRACT PEX1 is a type II AAA-ATPase that is indispensable for biogenesis and maintenance of the peroxisome, an organelle responsible for the primary metabolism of lipids, such as beta-oxidation and lipid biosynthesis. Recently, we demonstrated a striking structural similarity between its N-terminal domain and those of other membrane-related AAA-ATPases, such as valosine-containing protein (p97). The N-terminal domain of valosine-containing protein serves as an interface to its adaptor proteins p47 and Ufd1, whereas the physiologic interaction partner of the N-terminal domain of PEX1 remains unknown. Here we found that N-terminal domains isolated from valosine-containing protein, as well as from PEX1, bind phosphoinositides. The N-terminal domain of PEX1 appears to preferentially bind phosphatidylinositol 3-monophosphate and phosphatidylinositol 4-monophosphate, whereas the N-terminal domain of valosine-containing protein displays broad and nonspecific lipid binding. Although N-ethylmaleimide-sensitive fusion protein, CDC48 and Ufd1 have structures similar to that of valosine-containing protein, they displayed lipid specificity similar to that of the N-terminal domain of PEX1 in the assays. By mutational analysis, we demonstrate that a conserved arginine surrounded by hydrophobic residues is essential for lipid binding, despite very low sequence similarity between PEX1 and valosine-containing protein.

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Available from: Toshiyuki Shimizu, Aug 16, 2015
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    • "As depicted by Blue-Native PAGE analysis of cytosolic Pex1p from HEK293 cells, Pex1p is mostly in a homo-trimer, and less in a homo-hexamer. Crystal structure of the N-terminal domain of mouse Pex1p resembles valosin-containing protein (VCP/p97), another member of the AAA proteins [32] [33]. VCP/p97 forms a barrel-like homohexameric structure [34]. "
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    • "These subdomains are connected by a short linker and form an overall structure with a shallow groove similar to the N-terminal domains of p97/VCP or NSF [47]. Interestingly, the NTDs of p97/VCP and Pex1p show a common phospholipid-binding activity , which may support the attachment to their target membranes [48]. While no adaptor proteins interacting with Pex1p have yet been identified, the NTD of Pex6p has been demonstrated to interact with the tail-anchored membrane protein Pex15p, for which orthologues have been identified in mammals (Pex26p) and plants (APM9) [49– 51]. "
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    ABSTRACT: The recognition of the conserved ATP-binding domains of Pex1p, p97 and NSF led to the discovery of the family of AAA-type ATPases. The biogenesis of peroxisomes critically depends on the function of two AAA-type ATPases, namely Pex1p and Pex6p, which provide the energy for import of peroxisomal matrix proteins. Peroxisomal matrix proteins are synthesized on free ribosomes in the cytosol and guided to the peroxisomal membrane by specific soluble receptors. At the membrane, the cargo-loaded receptors bind to a docking complex and the receptor-docking complex assembly is thought to form a dynamic pore which enables the transition of the cargo into the organellar lumen. The import cycle is completed by ubiquitination- and ATP-dependent dislocation of the receptor from the membrane to the cytosol, which is performed by the AAA-peroxins. Receptor ubiquitination and dislocation are the only energy-dependent steps in peroxisomal protein import. The export-driven import model suggests that the AAA-peroxins might function as motor proteins in peroxisomal import by coupling ATP-dependent removal of the peroxisomal import receptor and cargo translocation into the organelle.
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    • "It has been suggested that this domain may be involved in interactions with ubiquitin-related molecules and may possess a putative adaptor or substrate binding site. In addition, it was demonstrated that the N-terminus of mammalian Pex1p is able to bind phosphoinositides (Shiozawa et al., 2006), but how this fits with the role of Pex1p in receptor recycling is unclear. Orthologs of Pex1p, Pex4p, Pex6p and Pex26p are present in A. nidulans and other filamentous fungi. "
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