Docking and Fast Fusion of Synaptobrevin Vesicles Depends on the Lipid Compositions of the Vesicle and the Acceptor SNARE Complex-Containing Target Membrane
Docking and Fast Fusion of Synaptobrevin Vesicles Depends on the Lipid Compositions of the Vesicle and the Acceptor SNARE Complex-Containing Target Membrane
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DOI：
10.1016/j.bpj.2010.09.011
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发表时间：
2010-11-03
影响因子：
3.4
通讯作者：
Tamm, Lukas K.
中科院分区：
文献类型：
--
作者：
Domanska, Marta K.;Kiessling, Volker;Tamm, Lukas K.
脂质环境对小突触泡蛋白2（Syb 2）囊泡与靶SNARE复合物膜的对接和融合的影响在具有高时间分辨率的平面支持膜融合测定中进行了研究。以前，我们表明，大约8个陷阱复合物需要融合磷脂酰胆碱（PC）和胆固醇模型膜在类似于20毫秒。在这里，我们提出的实验中，其中磷脂酰丝氨酸（PS）和磷脂酰乙醇胺（PE）加入到PC/胆固醇的混合物中，以不同的比例在Syb 2囊泡膜中，只有或在支持的双层和Syb 2囊泡。我们发现，PS和PE都降低了融合的可能性，这种减少是完全占囊泡膜中的脂质成分。然而，当囊泡（和靶膜）中的PE含量从0增加到30%时，对接效率增加。快速激活的SNARE复合物的分数随着PE含量的增加而降低。当至少5% PS和10% PE存在于两种膜中或5%和30% PE仅存在于囊泡膜中时，少至三个SNARE复合物足以支持膜融合。尽管所需的SNARE数量较少，但SNARE活化和融合速率几乎与先前在重构PC/胆固醇双层中报道的一样快，即，分别为10和类似于20 ms。
The influence of the lipid environment on docking and fusion of synaptobrevin 2 (Syb2) vesicles with target SNARE complex membranes was examined in a planar supported membrane fusion assay with high time-resolution. Previously, we showed that approximately eight SNARE complexes are required to fuse phosphatidylcholine (PC) and cholesterol model membranes in similar to 20 ms. Here we present experiments, in which phosphatidylserine (PS) and phosphatidylethanolamine (PE) were added to mixtures of PC/cholesterol in different proportions in the Syb2 vesicle membranes only or in both the supported bilayers and the Syb2 vesicles. We found that PS and PE both reduce the probability of fusion and that this reduction is fully accounted for by the lipid composition in the vesicle membrane. However, the docking efficiency increases when the PE content in the vesicle (and target membrane) is increased from 0 to 30%. The fraction of fast-activating SNARE complexes decreases with increasing PE content. As few as three SNARE complexes are sufficient to support membrane fusion when at least 5% PS and 10% PE are present in both membranes or 5% and 30% PE are present in the vesicle membrane only. Despite the smaller number of required SNAREs, the SNARE activation and fusion rates are almost as fast as previously reported in reconstituted PC/cholesterol bilayers, i.e., of 10 and similar to 20 ms, respectively.