Phospholipases D: An Update on Structure-Function Relationships.

Phospholipases D (PLD) are lipolytic and interfacial enzymes that hydrolyze the distal phosphodiester bond of phospholipid substrates. PLD are widespread in prokaryotes and eukaryotes and have various functions in bacteria, yeast, plants, and mammals. The PLD reaction frees phosphatidic acid (PA), which is an intermediate in the lipid pathway but also a signaling molecule involved in metabolic, cellular, and physiological processes. Depending on their primary structure, PLD belong to two different groups: the HKD family, characterized by an HXKX4D sequence that is often duplicated, and the non-HKD family, which does not harbor such a sequence. Crystal structures of bacterial, plant, and mammalian PLD recently obtained allow a better understanding of structure and function relationships of PLD belonging to the HKD family. This chapter is devised at reviewing the recent advances in PLD structures.