Conformational Dynamics Contribute to Phospholipase Cβ Activity

Abstract

Phospholipase Cβ (PLCβ) enzymes hydrolyze the lipid phosphatidylinositol‐4,5‐bisphosphate (PIP2) to produce the second messengers inositol‐1,4,5‐triphosphate (IP3) and diacylglycerol (DAG). Production of these second messengers leads to many diverse physiological responses, including vascular smooth muscle contraction and inflammation. Previous structural and functional studies of PLCβ have revealed a highly conserved catalytic core that adopts a compact, globular structure and forms the minimal fragment that retains lipase activity. However, a growing body of evidence suggests that the PLCβ PH domain, which interacts with EF hands and TIM barrel of the catalytic core in crystal structures, may be flexible in solution. Using a combination of small angle x‐ray scattering (SAXS), cross‐linking studies, and biochemical assays, we provide the first structural data demonstrating that the PH is in fact conformationally flexible in solution. The PH domain adopts two major states: an open state wherein the PH domain is extended away from the core, and a closed state consistent with the crystal structures. We also provide evidence that these conformational states are functionally significant. These findings provide new evidence of conformational heterogeneity of PLC enzymes in solution and reveal new insights into their roles in cell signaling and cardiovascular disease.Support or Funding InformationAmerican Heart Association Scientist Development Grant 16SDG29920017; Purdue Center for Cancer Research; Showalter Foundation; all to A.M.LThis abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.