tailieunhanh - Báo cáo khoa học: Lateral organization in Acholeplasma laidlawii lipid bilayer models containing endogenous pyrene probes

In membranes of the small prokaryoteAcholeplasma laid-lawii bilayer- and nonbilayer-prone glycolipids are major species, similar to chloroplast membranes. Enzymes of the glucolipid pathway keep certain important packing proper-ties of the bilayerin vivo, visualized especiallyas amonolayer curvature stress ( spontaneous curvature ). | Eur. J. Biochem. 270 1699-1709 2003 FEBS 2003 doi Lateral organization in Acholeplasma laidlawii lipid bilayer models containing endogenous pyrene probes Patrik Storm1 Lu Li2 Paavo Kinnunen3 4 and Ake Wieslander1 1 Department of Biochemistry and Biophysics Stockholm University Stockholm Sweden 2 Wallenberg Laboratory for Cardiovascular Research Goteborg University Sweden 3Department of Medical Chemistry Institute of Biomedicine Helsinki University Finland 4Memphys - Center for Biomembrane Physics University of Southern Denmark Odense Denmark In membranes of the small prokaryote Acholeplasma laid-lawii bilayer- and nonbilayer-prone glycolipids are major species similar to chloroplast membranes. Enzymes of the glucolipid pathway keep certain important packing properties of the bilayer in vivo visualized especially as a monolayer curvature stress spontaneous curvature . Two key enzymes depend in a cooperative fashion on substantial amounts of the endogenous anionic lipid phosphatidylglycerol PG for activity. The lateral organization of five unsaturated A. laidlawii lipids was analyzed in liposome model bilayers with the use of endogenously produced pyrene-lipid probes and extensive experimental designs. Of all lipids analyzed PG especially promoted interactions with the precursor diacylglycerol DAG as revealed from pyrene excimer ratio le Im responses. Significant interactions were also recorded within the major nonbilayer-prone monoglucosylDAG MGlcDAG lipids. The anionic precursor phosphatidic acid PA was without effects. Hence a heterogeneous lateral lipid organization was present in these liquid-crystalline bilayers. The MGlcDAG synthase when binding at the PG bilayer interface decreased acyl chain ordering increase of membrane free volume according to a bis-pyrene-lipid probe but the enzyme did not influence the bulk lateral lipid organization as recorded from DAG or PG probes. It is concluded that the concentration of the .