Structural basis of phosphatidylcholine recognition by the C2-domain of cytosolic phospholipase A2α
Abstract
Ca2+-stimulated translocation of cytosolic phospholipase A2α (cPLA2α) to the Golgi induces arachidonic acid production, the rate-limiting step in pro-inflammatory eicosanoid synthesis. Structural insights into the cPLA2α preference for phosphatidylcholine (PC)-enriched membranes have remained elusive. Here, we report cPLA2α C2-domain structure (2.2Å resolution) containing bound 1,2-dihexanoyl-sn-glycero-3-phosphocholine (DHPC) and Ca2+ ions. Two Ca2+ are complexed at locations previously reported for lipid-free C2-domain. One of these Ca2+ along with a third Ca2+ bridge the C2-domain to the DHPC phosphate group, which also interacts with Asn65. Tyr96 plays a key role in lipid headgroup recognition via cation-π interaction with the PC trimethylammonium group. Mutagenesis analyses confirm Tyr96 and Asn65 function in PC binding selectivity by C2-domain and regulation of cPLA2α activity. The differing DHPC-binding mode of cPLA2α C2-domain, compared to phosphatidylserine or phosphatidylinositol 4,5-bisphosphate binding by other C2-domains, expands and deepens knowledge of lipid-binding mechanisms mediated by C2-domains.
Data availability
Diffraction data have been deposited in PDB under the accession code 6IEJ
Article and author information
Author details
Funding
National Institutes of Health (HL125353)
- Rhoderick E Brown
Ministry of Education, Culture, Sports, Science, and Technology
- Yoshinori Hirano
U.S. Department of Veterans Affairs (I BX001792)
- Charles E Chalfant
The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.
Reviewing Editor
- Arun Radhakrishnan, University of Texas Southwestern Medical Center, United States
Version history
- Received: December 28, 2018
- Accepted: May 3, 2019
- Accepted Manuscript published: May 3, 2019 (version 1)
- Version of Record published: June 5, 2019 (version 2)
- Version of Record updated: November 29, 2021 (version 3)
Copyright
© 2019, Hirano et al.
This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.
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Further reading
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- Cell Biology
- Structural Biology and Molecular Biophysics
Mutations in the human PURA gene cause the neurodevelopmental PURA syndrome. In contrast to several other monogenetic disorders, almost all reported mutations in this nucleic acid-binding protein result in the full disease penetrance. In this study, we observed that patient mutations across PURA impair its previously reported co-localization with processing bodies. These mutations either destroyed the folding integrity, RNA binding, or dimerization of PURA. We also solved the crystal structures of the N- and C-terminal PUR domains of human PURA and combined them with molecular dynamics simulations and nuclear magnetic resonance measurements. The observed unusually high dynamics and structural promiscuity of PURA indicated that this protein is particularly susceptible to mutations impairing its structural integrity. It offers an explanation why even conservative mutations across PURA result in the full penetrance of symptoms in patients with PURA syndrome.