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Fluorescence Correlation Spectroscopy Of Phosphatidylinositolspecific Phospholipase C Monitors The Interplay Of Substrate And Activator Lipid Binding, Mingming Pu, Mary F. Roberts, Anne Gershenson
Fluorescence Correlation Spectroscopy Of Phosphatidylinositolspecific Phospholipase C Monitors The Interplay Of Substrate And Activator Lipid Binding, Mingming Pu, Mary F. Roberts, Anne Gershenson
Anne Gershenson
Phosphatidylinositol-specific phospholipase C (PI-PLC) enzymes simultaneously interact with the substrate, PI, and with non-substrate lipids such as phosphatidylcholine (PC). For Bacillus thuringiensis PI-PLC these interactions are synergistic with maximal catalytic activity observed at low to moderate mole fractions of PC (XPC) and maximal binding occurring at low mole fractions of anionic lipids. It has been proposed that residues in α helix B help modulate membrane binding and that dimerization on the membrane surface both increases affinity for PC and activates PI-PLC yielding the observed PI/PC synergy. Vesicle binding and activity measurements using a variety of PI-PLC mutants support many aspects …