InterPro domain: IPR036938

This entry represents type 2 phosphatidic acid phosphatase (PAP2; 3.1.3.4 ) enzymes, such as phosphatidylglycerophosphatase B 3.1.3.27 from Escherichia coli. PAP2 enzymes have a core structure consisting of a 5-helical bundle, where the beginning of the third helix binds the cofactor [ 1 ]. PAP2 enzymes catalyse the dephosphorylation of phosphatidate, yielding diacylglycerol and inorganic phosphate [ 2 ]. In eukaryotic cells, PAP activity has a central role in the synthesis of phospholipids and triacylglycerol through its product diacylglycerol, and it also generates and/or degrades lipid-signalling molecules that are related to phosphatidate.

Other related enzymes have a similar core structure, including haloperoxidases such as bromoperoxidase (contains one core bundle, but forms a dimer), chloroperoxidases (contains two core bundles arranged as in other family dimers), bacitracin transport permease from Bacillus licheniformis, glucose-6-phosphatase from rat. The vanadium-dependent haloperoxidases exclusively catalyse the oxidation of halides, and act as histidine phosphatases, using histidine for the nucleophilic attack in the first step of the reaction [ 3 ]. Amino acid residues involved in binding phosphate/vanadate are conserved between the two families, supporting a proposal that vanadium passes through a tetrahedral intermediate during the reaction mechanism.

1. X-ray structures of a novel acid phosphatase from Escherichia blattae and its complex with the transition-state analog molybdate. EMBO J. 19, 2412-23
2. Roles of phosphatidate phosphatase enzymes in lipid metabolism. Trends Biochem. Sci. 31, 694-9
3. Structural and functional comparisons between vanadium haloperoxidase and acid phosphatase enzymes. J. Mol. Recognit. 15, 291-6