Membrane Fusion Induced by a Short Fusogenic Peptide Is Assessed by Its Insertion and Orientation into Target Bilayers
详细信息 查看全文
- 作者：Isabelle Martin ; Eve-Isabelle Pé ; cheur ; Jean-Marie Ruysschaert ; and Dick Hoekstra
- 刊名：Biochemistry
- 出版年：1999
- 出版时间：July 20, 1999
- 年：1999
- 卷：38
- 期：29
- 页码：9337 - 9347
- 全文大小：105K
- 年卷期：v.38,no.29(July 20, 1999)
- ISSN：1520-4995
文摘
To clarify the molecular mechanism by which an amphipathic negatively charged peptideconsisting of 11 residues (WAE) induces fusion, and the relevance of these features for fusion, its modeof insertion and orientation into target bilayers were investigated. Using attenuated total reflection Fouriertransform infrared spectroscopy (ATR-FTIR) in combination with techniques based on tryptophanfluorescence, the peptide was found to form an 
-helix, shallowly inserted into the membrane to whichit is anchored. Interestingly, in the presence of target membranes, WAE inserts into the target bilayer asan -helix oriented almost parallel to the lipid acyl chains. The accessibility of the peptide to eitheracrylamide (as an aqueous quencher of Trp fluorescence) or deuterium oxide (on the course of an FTIRdeuteration kinetics) was lower in the presence than in the absence of target membranes, confirming thatunder those conditions, the peptide was shielded from the aqueous environment. Since fusion experimentshave shown a temperature dependence, the effect of this later parameter on the structure and mode ofinsertion of the peptide was also analyzed. In the presence of target membrane, but not in their absence,the amount of -helical structure increased with temperature, reflecting a similar temperature-dependentincrease in the rate and extent of WAE-induced fusion. Also, the extent of penetration of the helix intothe target membrane was greater at 37 
C than at lower temperatures. This temperature-dependent distinctionwas revealed by a decreased accessibility of the peptide to deuterium oxide and acrylamide at 37 C ascompared to that at lower temperatures. These data underscore the role of peptide structure, peptidepenetration, and orientation in the mechanism of protein-induced membrane fusion.
-helix, shallowly inserted into the membrane to whichit is anchored. Interestingly, in the presence of target membranes, WAE inserts into the target bilayer asan -helix oriented almost parallel to the lipid acyl chains. The accessibility of the peptide to eitheracrylamide (as an aqueous quencher of Trp fluorescence) or deuterium oxide (on the course of an FTIRdeuteration kinetics) was lower in the presence than in the absence of target membranes, confirming thatunder those conditions, the peptide was shielded from the aqueous environment. Since fusion experimentshave shown a temperature dependence, the effect of this later parameter on the structure and mode ofinsertion of the peptide was also analyzed. In the presence of target membrane, but not in their absence,the amount of -helical structure increased with temperature, reflecting a similar temperature-dependentincrease in the rate and extent of WAE-induced fusion. Also, the extent of penetration of the helix intothe target membrane was greater at 37 C than at lower temperatures. This temperature-dependent distinctionwas revealed by a decreased accessibility of the peptide to deuterium oxide and acrylamide at 37 C ascompared to that at lower temperatures. These data underscore the role of peptide structure, peptidepenetration, and orientation in the mechanism of protein-induced membrane fusion.