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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    ABSTRACT: Peroxisome is a single-membrane organelle in eukaryotes. The functional importance of peroxisomes in humans is highlighted by peroxisome-deficient peroxisome biogenesis disorders such as Zellweger syndrome. Two AAA peroxins, Pex1p and Pex6p, are encoded by PEX1 and PEX6, the causal genes for PBDs of complementation groups 1 and 4, respectively. PEX26 responsible for peroxisome biogenesis disorders of complementation group 8 codes for C-tail-anchored type-II membrane peroxin Pex26p, the recruiter of Pex1p-Pex6p complexes to peroxisomes. Pex1p is targeted to peroxisomes in a manner dependent on ATP hydrolysis, while Pex6p targeting requires ATP but not its hydrolysis. Pex1p and Pex6p are most likely regulated in their peroxisomal localization onto Pex26p via conformational changes by ATPase cycle. Pex5p is the cytosolic receptor for peroxisome matrix proteins with peroxisome targeting signal type-1 and shuttles between the cytosol and peroxisomes. AAA peroxins are involved in the export from peroxisomes of Pex5p. Pex5p is ubiquitinated at the conserved cysteine11 in a form associated with peroxisomes. Pex5p with a mutation of the cysteine11 to alanine, termed Pex5p-C11A, abrogates peroxisomal import of proteins harboring peroxisome targeting signals 1 and 2 in wild-type cells. Pex5p-C11A is imported into peroxisomes but not exported, hence suggesting an essential role of the cysteine residue in the export of Pex5p.
    Biochimica et Biophysica Acta 11/2011; 1823(1):145-9. DOI:10.1016/j.bbamcr.2011.10.012 · 4.66 Impact Factor
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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.
    Biochimica et Biophysica Acta 09/2011; 1823(1):150-8. DOI:10.1016/j.bbamcr.2011.09.005 · 4.66 Impact Factor
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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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    ABSTRACT: Fungal microbodies (peroxisomes) are inducible organelles that proliferate in response to nutritional cues. Proteins involved in peroxisome biogenesis/proliferation are designated peroxins and are encoded by PEX genes. An autophagy-related process, termed pexophagy, is responsible for the selective removal of peroxisomes from the cell. Several genes involved in pexophagy are also required for autophagy and are collectively known as ATG genes. We have re-analysed the Aspergillus nidulans genome for the presence of PEX and ATG genes and have identified a number of previously missed genes. Also, we manually determined the correct intron positions in each identified gene. The data show that in A. nidulans and related fungi the basic set of genes involved in peroxisome biogenesis or degradation are conserved. However, both processes have features that more closely resemble organelle formation/degradation in mammals rather than yeast. Thus, filamentous fungi like A. nidulans are ideal model systems for peroxisome homeostasis in man.
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