Yor022c protein is a phospholipase A1 that localizes to the mitochondrial matrix

Abstract

In mammals, three types of intracellular phospholipase A1 (iPLA1) enzymes have been characterized and are thought to be involved in various cellular processes such as phospholipid metabolism, organelle biogenesis, and membrane trafficking. In this study we analyzed the unique iPLA1-like protein, Yor022c, in the budding yeast Saccharomyces cerevisiae. By the mass spectrometry analysis, we demonstrate that Yor022c is actually a phospholipase displaying sn-1-specific activity toward phosphatidylcholine, phosphatidylethanolamine, and phosphatidic acid, generating 2-acyl lysophospholipids. GFP-fused Yor022c co-stained with the mitochondrial dye MitoTracker, indicating that, unlike its mammalian counterparts, it is a mitochondrial protein. Further biochemical fractionation experiment combined with protease sensitivity assay showed that Yor022c localizes to the mitochondrial matrix. Thus Yor022c is the first PLA1 putatively involved in the maintenance of sn-1 acyl chains of phospholipids in the mitochondrial inner membrane.