eLife (May 2019)

Structural basis of phosphatidylcholine recognition by the C2–domain of cytosolic phospholipase A2α

  • Yoshinori Hirano,
  • Yong-Guang Gao,
  • Daniel J Stephenson,
  • Ngoc T Vu,
  • Lucy Malinina,
  • Dhirendra K Simanshu,
  • Charles E Chalfant,
  • Dinshaw J Patel,
  • Rhoderick E Brown

DOI
https://doi.org/10.7554/eLife.44760
Journal volume & issue
Vol. 8

Abstract

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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 the structure of the cPLA2α C2-domain (at 2.2 Å resolution), which contains bound 1,2-dihexanoyl-sn-glycero-3-phosphocholine (DHPC) and Ca2+ ions. Two Ca2+ are complexed at previously reported locations in the lipid-free C2-domain. One of these Ca2+ions, along with a third Ca2+, bridges 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 that Tyr96 and Asn65 function in PC binding selectivity by the C2-domain and in the regulation of cPLA2α activity. The DHPC-binding mode of the cPLA2α C2-domain, which differs from phosphatidylserine or phosphatidylinositol 4,5-bisphosphate binding by other C2-domains, expands and deepens knowledge of the lipid-binding mechanisms mediated by C2-domains.

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