Crawford, M. A.; Bennett, M. B.; Qin, Y.; Cano, K. E.; Gonzalez, T. G.; Mojidra, R.; Falzone, M. E.

Phospholipase C-{beta} (PLC{beta}) enzymes are essential effectors of G protein-coupled receptor signaling that hydrolyze phosphatidylinositol 4,5-bisphosphate (PIP2) at the plasma membrane to generate the second messengers inositol trisphosphate and diacylglycerol. PLC{beta}s play essential roles in diverse physiological processes, including cardiac and neuronal function, macrophage activation, and the pathogenesis of diseases such as hypertrophic cardiomyopathy. PLC{beta} enzymes are unique in that they are aqueous-soluble and must partition onto the membrane surface to access their substrate, making membrane association a critical regulatory step. For example, we recently demonstrated that G{beta}{gamma} activates PLC{beta} by membrane recruitment and orientation of the catalytic core on the membrane surface. Although PLC{beta} membrane recruitment is required for function, the molecular determinants governing this process remain incompletely understood. Using a quantitative membrane partitioning assay, we show that robust membrane association of PLC{beta} requires anionic phospholipids, whereas polar phospholipids cannot substitute. Membrane partitioning exhibits a steep dependence on anionic lipid abundance, which is mediated by electrostatic interactions between negatively charged lipids and basic residues within the distal C-terminal domain of PLC{beta}. We further demonstrate that anionic lipids cooperate with G{beta}{gamma} to regulate PLC{beta} membrane recruitment, such that the magnitude of G{beta}{gamma}-dependent recruitment is dictated by membrane anionic lipid content. These findings reconcile previous discrepancies regarding G{beta}{gamma}-mediated PLC{beta} membrane recruitment and establish membrane electrostatics as a key regulatory input that integrates lipid composition with G protein signaling to regulate PLC{beta} activity.