A cytosolic phospholipase A₂-like protein in the filamentous fungus Aspergillus oryzae localizes to the intramembrane space of the mitochondria

In mammalian cells, cytosolic phospholipase A₂ (cPLA ₂) displays a variety of activities through the release of arachidonic acid in response to cellular stimuli. In this study, we characterize the putative cPLA₂-like protein, AoPlaA, in the filamentous fungus Aspergillus oryzae. When AoPlaA-EGFP was expressed in A. oryzae, it localized to the tubular structures that was costained by the marker dye for the mitochondria. A biochemical fractionation experiment showed that AoPlaA was present in the mitochondria-enriched fraction. The presence of an N-terminal cleavable mitochondrial targeting signal in AoPlaA was demonstrated by N-terminal amino acid sequence analysis, and by showing that chimeric proteins consisting of N-terminal 65 or 50 amino acids of AoPlaA fused to enhanced green fluorescent protein (EGFP) localized to the mitochondria. Submitochondrial fractionation of AoPlaA expressed in Saccharomyces cerevisiae demonstrated that AoPlaA localizes to the intramembrane space of the mitochondria. Taken together, the results presented here demonstrate a novel, submitochondrial localization of the cPLA₂-like protein in the filamentous fungi.