Analysis of PI-PLC Binding to PC and PMe Vesicle Surfaces Using EPR and NMR

Abstract

Phosphatidylinositol-specific phospholipase C (PI-PLC) is an enzyme important in membrane-associated signal transduction in eukaryotes, and pathogenic factors in bacteria. It catalyzes the conversion of PI to DAG and cIP, which is further converted to I-1-P. The phospholipid PC has been shown to activate cIP hydrolysis. EPR and NMR were used to examine PI-PLC binding to PC and PMe vesicles through the use of spin labels attached to cysteine mutants. It was concluded that the spin label interacted more significantly with the phosphorus of PC than that of PMe. The results also suggested the -OCH3 group was preferred over the -N(CH3)3 group, and that the protein penetrated into the bulk methylene region of the phospholipid bilayer.