Activation of a specific phospholipid fatty acyl hydrolase in Dunaliella salina microsomes during acclimation to low growth temperature

Abstract

Dunaliella salina microsomes, but not chloroplasts, contain a fatty acyl hydrolase with high activity towards endogenous or exogenous phosphatidylglycerol and phosphatidylethanolamine. There is relatively little activity towards other phospholipids or added monogalactosyldiacylglycerol. Lipolysis is most active in the presence of 10 mM Ca 2+ and is enhanced by added calmodulin. Microsomal acyl hydrolase activity in 30°C-grown cells is low when measured in vitro at 12°C but increases rapidly after cells are chilled to 12°C, finally attaining more than 13-times the pre-chilling value. The changing capacity for lipolysis may explain the key role of microsomes in the acclimation of Dunaliella to low temperature.