Phospholipase C activity-induced fusion of pure lipid model membranes. A freeze fracture study

• Published in: Biochimica et biophysica acta Vol. 1068; no. 2; pp. 249 - 253
• Main Authors: Burger, K N, Nieva, J L, Alonso, A, Verkleij, A J
• Format: Journal Article
• Language: English
• Published: Netherlands 30.09.1991
• Subjects: Freeze Fracturing; Lipid Bilayers - chemistry; Microscopy, Electron - methods; Type C Phospholipases - chemistry
• ISSN: 0006-3002; 1878-2434
• DOI: 10.1016/0005-2736(91)90216-U

The structural effects of in situ production of diacylglycerol by phospholipase C in pure lipid model membranes have been examined by freeze fracture electron microscopy. Phospholipase C-activity induces massive aggregation and fusion of large unilamellar lipid vesicles and leads to the formation of a 'sealed' lipid aggregate; the outer membrane of this aggregate appears to be continuous. In some areas lipid arranges into a honeycomb structure; this structure is probably a precursor of a discontinuous inverted (type II) cubic phase. Similarly, enzyme treatment of multilamellar vesicles leads to extensive membrane fusion and vesiculation. Thus morphological evidence is obtained showing the ability of phospholipase C to induce bilayer destabilization and fusion. It is speculated that phospholipase C-induced membrane fusion involves a type II fusion intermediate induced by diacylglycerol produced locally.