title: Al(3+)-mediated changes on membrane fluidity affects the activity of PI-PLC but not of PLC.
abstract: We investigated whether Al(3+)-mediated changes in membrane fluidity can affect the activity of prokaryotic enzymes phospholipase C (PLC) and phospholipase C-phosphatidyl inositol specific (PI-PLC) in liposomes of phosphatidyl choline (PC), PC:phosphatidyl inositol (PI), or PC and polyphosphoinositides (PPI). Al(3+) (10-100 microM) promoted membrane rigidification, evaluated with the probes 1,6-diphenyl-1,3,5-hexatriene and Laurdan, and followed the order: PC:PPI>PC:PI>PC. Al(3+) (25 and 50 microM) did not affect PLC-mediated hydrolysis of PC, PI and PIP(2), but stimulated PIP hydrolysis (48.6%). PI-PLC did not affect PC, PI, and PIP concentrations, but caused a 67% decrease in PIP(2). Al(3+) significantly inhibited PIP(2) hydrolysis in a concentration-dependent (25-50 microM) manner. Results suggest that the inhibition of PIP(2) hydrolysis by Al(3+) could be partially due to a higher lipid packing induced by Al(3+) which could affect the interaction between the enzyme and its substrate.
authors.affiliation: Department of Biological Chemistry, IQUIFIB (UBA-CONICET), School of Pharmacy and Biochemistry, University of Buenos Aires, Buenos Aires, Argentina.
authors.forename: Sandra V
authors.initials: SV
authors.lastname: Verstraeten
authors.forename: Marcela S
authors.initials: MS
authors.lastname: Villaverde
authors.forename: Patricia I
authors.initials: PI
authors.lastname: Oteiza
mesh_terms: D000535:Aluminum / Q000494:pharmacology*; D005454:Fluorescence Polarization; D006868:Hydrolysis; D008081:Liposomes; D008560:Membrane Fluidity / Q000187:drug effects*; D043265:Phosphatidylinositol Diacylglycerol-Lyase / Q000378:metabolism*; D054801:Phosphoinositide Phospholipase C; D010738:Type C Phospholipases / Q000378:metabolism*
chemical_list: D008081:Liposomes; D000535:Aluminum; D010738:Type C Phospholipases; D054801:Phosphoinositide Phospholipase C; D043265:Phosphatidylinositol Diacylglycerol-Lyase