Correlation of vesicle binding and phospholipid dynamics with phospholipase C activity: insights into phosphatidylcholine activation and surface dilution inhibition.

ABSTRACT: The enzymatic activity of the peripheral membrane protein, phosphatidylinositol-specific phospholipase C (PI-PLC), is increased by nonsubstrate phospholipids with the extent of enhancement tuned by the membrane lipid composition. For Bacillus thuringiensis PI-PLC, a small amount of phosphatidylcholine (PC) activates the enzyme toward its substrate PI; above 0.5 mol fraction PC (XPC), enzyme activity decreases substantially. To provide a molecular basis for this PC-dependent behavior, we used fluorescence correlation spectroscopy to explore enzyme binding to multicomponent lipid vesicles composed of PC and anionic phospholipids (that bind to the active site as substrate analogues) and high resolution field cycling 31P NMR methods to estimate internal correlation times (tauc) of phospholipid

SUBMITTER: Pu M 

PROVIDER: S-EPMC2713506 | biostudies-literature | 2009 Jun

REPOSITORIES: biostudies-literature