The accessory domains of Phospholipase D regulate its localization and activity in Drosophila photoreceptors

Phospholipase D (PLD) is activated during the response of animal cells to a large number of extracellular signals including growth factors, hormones and other extracellular stimuli. The product of PLD activity, phosphatidic acid (PA) is thought to act as a signalling molecule in cells. Since both the substrate, phosphatidylcholine and product phosphatidic acid (PA) are membrane anchored lipids, the precise localization and activation of PLD at specific locations in cells is critical. Here we report that that the precise localization of Drosophila PLD (dPLD) in photoreceptors is critical to maintain the structure of these cells during illumination. This localization of dPLD is dependent on its N-terminal PH domain; deletion of the PH domain (dPLD{Delta}PH) results in mis localization of the protein, loss of functional activity and dPLD{Delta}PHis unable to rescue the phenotypes of dPLD loss of function. By contrast, deletion of the PX domain (dPLD{Delta}PX) does not impact the localization of dPLD but enhances the functional activity of the protein. Thus the PH and PX domains of dPLD regulate its localization and activity respectively.