The Cytosolic Phospholipase A2α N-Terminal C2 Domain Binds and Oligomerizes on Membranes with Positive Curvature
by
Katherine E. Ward 1, 
Ranjan Sengupta 2
, James P. Ropa 1,†, Souad Amiar 2 and Robert V. Stahelin 2,3,*
Katherine E. Ward 1, Ranjan Sengupta 2, James P. Ropa 1,†, Souad Amiar 2 and Robert V. Stahelin 2,3,*
1
Department of Chemistry and Biochemistry, University of Notre Dame, South Bend, IN 46556, USA
2
Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, IN 47906, USA
3
Purdue Center for Cancer Research, Purdue University, West Lafayette, IN 47907, USA
*
Author to whom correspondence should be addressed.
†
Current address: Department of Microbiology and Immunology, Indiana University School of Medicine, Indianapolis, IN 46202, USA.
Biomolecules 2020, 10(4), 647; https://doi.org/10.3390/biom10040647
Received: 11 March 2020 / Revised: 16 April 2020 / Accepted: 19 April 2020 / Published: 22 April 2020
(This article belongs to the Special Issue 2020 Feature Papers by Biomolecules’ Editorial Board Members)
Group IV phospholipase A2α (cPLA2α) regulates the production of prostaglandins and leukotrienes via the formation of arachidonic acid from membrane phospholipids. The targeting and membrane binding of cPLA2α to the Golgi involves the N-terminal C2 domain, whereas the catalytic domain produces arachidonic acid. Although most studies of cPLA2α concern its catalytic activity, it is also linked to homeostatic processes involving the generation of vesicles that traffic material from the Golgi to the plasma membrane. Here we investigated how membrane curvature influences the homeostatic role of cPLA2α in vesicular trafficking. The cPLA2α C2 domain is known to induce changes in positive membrane curvature, a process which is dependent on cPLA2α membrane penetration. We showed that cPLA2α undergoes C2 domain-dependent oligomerization on membranes in vitro and in cells. We found that the association of the cPLA2α C2 domain with membranes is limited to membranes with positive curvature, and enhanced C2 domain oligomerization was observed on vesicles ~50 nm in diameter. We demonstrated that the cPLA2α C2 domain localizes to cholesterol enriched Golgi-derived vesicles independently of cPLA2α catalytic activity. Moreover, we demonstrate the C2 domain selectively localizes to lipid droplets whereas the full-length enzyme to a much lesser extent. Our results therefore provide novel insight into the molecular forces that mediate C2 domain-dependent membrane localization in vitro and in cells.
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Keywords:
cytosolic phospholipase A2α (cPLA2α); electron microscopy; Golgi; membrane bending; membrane curvature; C2 domain; oligomerization
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MDPI and ACS Style
Ward, K.E.; Sengupta, R.; Ropa, J.P.; Amiar, S.; Stahelin, R.V. The Cytosolic Phospholipase A2α N-Terminal C2 Domain Binds and Oligomerizes on Membranes with Positive Curvature. Biomolecules 2020, 10, 647.
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