InterPro: IPR000326 Phosphatidic acid phosphatase type 2/haloperoxidase

This entry represents type 2 phosphatidic acid phosphatase (PAP2; EC:3.1.3.4) enzymes, such as phosphatidylglycerophosphatase B EC: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.