SAPOSIN-C INDUCES PH-DEPENDENT DESTABILIZATION AND FUSION OF PHOSPHATIDYLSERINE-CONTAINING VESICLES

Citation
Am. Vaccaro et al., SAPOSIN-C INDUCES PH-DEPENDENT DESTABILIZATION AND FUSION OF PHOSPHATIDYLSERINE-CONTAINING VESICLES, FEBS letters, 349(2), 1994, pp. 181-186
Citations number
25
Categorie Soggetti
Biophysics,Biology
Journal title
ISSN journal
00145793
Volume
349
Issue
2
Year of publication
1994
Pages
181 - 186
Database
ISI
SICI code
0014-5793(1994)349:2<181:SIPDAF>2.0.ZU;2-G
Abstract
We have previously shown that saposin C (Sap C), a glucosylceramidase activator protein, interacts with phosphatidylserine (PS) large unilam ellar vesicles (LUV), promoting the glucosylceramidase binding to the bilayer [(1993) FEBS Lett. 336, 159-162]. In the present paper the con sequences of the Sap C interaction on the lipid organization of the ve sicles are reported. It was found that Sap C perturbs the PS bilayer a s shown by the release of an encapsulated fluorescent dye. Three diffe rent procedures, resonance energy transfer, gel filtration and electro n microscopy, indicated that the activator protein is also able to mak e PS liposomes fuse. The effects of Sap C on PS vesicles were observed at low but not at neutral pH. The lipid composition of the bilayer al so affected the Sap C-induced destabilization; in fact, the presence o f PS in mixed LUV was essential for significant leakage to occur. Thes e results demonstrate for the first time that Sap C is a protein capab le of destabilizing and fusing acidic phospholipid-containing membrane s in a pH-dependent fashion.