Conformational Regulation of Phospholipase C Enzymes

Abstract

Phospholipase C (PLC) enzymes, in particular the PLCβ and PLCɛ subfamilies, are essential for normal cellular function in the cardiovascular system where they generate second messengers in response to extracellular signaling that increase calcium levels and activate protein kinase C. Crystal structures of PLCβ have provided some insights into its architecture and regulation, but there is no published structural data for PLCɛ or any catalytically active fragment of the enzyme. We have used small angle X‐ray scattering, electron microscopy, and biochemical assays to begin characterizing the solution structures and regulation of PLCɛ and PLCβ. We find that PLCɛ is conformationally dynamic in solution and that its PH domain is essential for maximum basal activity. We also find PLCβ adopts multiple conformations in solution, wherein its PH domain and EF hands are extended away from the catalytic core. Using site‐directed mutagenesis and functional assays, we find that stabilization of the PH domain in its extended or closed conformation impacts its activity. Taken together, our data support a more complex and global model for PLC regulation, wherein the conformation of the PH domain and EF hands relative to the catalytic core modulates its lipase activity at the membrane.Support or Funding InformationThis work is supported by an American Cancer Society Institutional Research Grant (IRG‐14‐190‐56) to the Purdue University Center for Cancer Research and an American Heart Association Scientist Development Grant 16SDG29930017 to A.M.L.This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.