Subcellular localization and lysophospholipase/transacylation activities of human group IVC phospholipase A2 (cPLA2gamma).
cPLA2gamma was identified as an ortholog of cPLA2alpha, which is a key enzyme in eicosanoid production. cPLA2gamma was reported to be located in endoplasmic reticulum (ER) and mitochondria and to have lysophospholipase activity beside phospholipase A2 (PLA2) activity. However, subcellular localization, mechanism of membrane binding, regulation and physiological function have not been fully established. In the present study, we examined the subcellular localization and enzymatic properties of cPLA2gamma with C-terminal FLAG-tag. We found that cPLA2gamma was located not only in ER but also mitochondria even in the absence of the prenylation. Purified recombinant cPLA2gamma catalyzed an acyltransferase reaction from one molecule of lysophosphatidylcholine (LPC) to another, forming phosphatidylcholine (PC). LPC or lysophosphatidylethanolamine acted as acyl donor and acceptor, but lysophosphatidylserine, lysophosphatidylinositol and lysophosphatidic acid (LPA) did not. PC and phosphatidylethanolamine (PE) also acted as weak acyl donors. Reaction conditions changed the balance of lysophospholipase and transacylation activities, with addition of LPA/PA, pH>8, and elevated temperature markedly increasing transacylation activity; this suggests that lysophospholipase/transacylation activities of cPLA2gamma may be regulated by various factors. As lysophospholipids are known to accumulate in ischemia heart and to induce arryhthmia, the cPLA2gamma that is abundant in heart may have a protective role through clearance of lysophospholipids by its transacylation activity.
Yamashita
Atsushi
A
Faculty of Pharmaceutical Sciences, Teikyo University, Sagamiko, Sagamihara, Kanagawa 229-0195, Japan. ayamashi@pharm.teikyo-u.ac.jp
Tanaka
Ken
K
Kamata
Ryo
R
Kumazawa
Tsukasa
T
Suzuki
Naotaka
N
Koga
Hiroki
H
Waku
Keizo
K
Sugiura
Takayuki
T
D000215:Acylation / Q000187:drug effects; D020816:Amino Acid Motifs; D004591:Electrophoresis, Polyacrylamide Gel; D000939:Epitopes; D054513:Group IV Phospholipases A2 / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism*; D006367:HeLa Cells; D006801:Humans; D006863:Hydrogen-Ion Concentration / Q000187:drug effects; D008244:Lysophosphatidylcholines / Q000737:chemistry / Q000378:metabolism; D008245:Lysophospholipase / Q000378:metabolism*; D008954:Models, Biological; D017830:Octoxynol / Q000494:pharmacology; D021381:Protein Transport / Q000187:drug effects; D011993:Recombinant Fusion Proteins / Q000302:isolation & purification / Q000378:metabolism; D012995:Solubility / Q000187:drug effects; D013347:Subcellular Fractions / Q000187:drug effects / Q000201:enzymology; D013379:Substrate Specificity / Q000187:drug effects; D013696:Temperature
D000939:Epitopes; D008244:Lysophosphatidylcholines; D011993:Recombinant Fusion Proteins; D017830:Octoxynol; C472331:PLA2G4C protein, human; D054513:Group IV Phospholipases A2; D008245:Lysophospholipase