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Abstract

The phospholipase A2s (PLA2s) are a diverse group of enzymes that hydrolyze the sn-2 fatty acid from phospholipids and play a role in a wide range of physiological functions. A 61-kDa calcium-independent PLA2, termed cPLA2γ, was identified as an ortholog of cPLA2α with approximately 30% overall sequence identity. cPLA2γ contains a potential prenylation motif at its C terminus, and is known to have PLA2 and lysophospholipase activities, but its physiological roles have not been clarified. In the present study, we expressed various forms of recombinant cPLA2γ, including non-prenylated and non-cleaved forms, in order to investigate the effects of C-terminal processing. We examined the expression of the wild type and non-prenylated (SCLA) forms of cPLA2γ, and found that the SCLA form was expressed normally and retained almost full activity. Expression of the prenylated and non-cleaved form of cPLA2γ using yeast mutants lacking prenyl protein proteases AFC1 (a-factor–converting enzyme) and RCE1 (Ras-converting enzyme) revealed decreased expression in the mutant strain compared to that in the wild type yeast, suggesting that complete C-terminal processing is important for the functional expression of cPLA2γ. In addition, cPLA2γ was found to have coenzyme A (CoA)–independent transacylation and lysophospholipid (LPL) dismutase (LPLase/transacylase) activities, suggesting that it may be involved in fatty acid remodeling of phospholipids and the clearance of toxic lysophospholipids in cells.

CAAX box motif, cPLA2γ, lysophospholipase, phospholipase A2, prenylprotein endoprotease, transacylation
CoA, coenzyme A, GPC, sn-glycero-3-phosphocholine, GPE, sn-glycero-3-phosphoethanolamine, LPC, lysophosphatidylcholine, LPE, lysophosphatidylethanolamine, LPL, lysophospholipid, PC, phosphatidylcholine, PE, phosphatidylethanolamine, fatty acids are designated in terms of the number of carbon atoms and double bonds, e.g., 20:4 denotes twenty carbons and four double bonds (arachidonate). Unless otherwise indicated, lysophospholipids are the 1-acyl isomers.
© 2005 The Japanese Biochemical Society.
Issue Section:
Biochemistry
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