Glycolipid Crosslinking Is Required for Cholera Toxin to Partition Into and Stabilize Ordered Domains.
Glycolipid Crosslinking Is Required for Cholera Toxin to Partition Into and Stabilize Ordered Domains.
复制标题
DOI：
10.1016/j.bpj.2016.11.008
复制
发表时间：
2016-12
影响因子：
3.4
通讯作者：
K. Raghunathan;Tiffany Wong;D. Chinnapen;W. Lencer;M. Jobling;A. Kenworthy
中科院分区：
文献类型：
--
作者：
K. Raghunathan;Tiffany Wong;D. Chinnapen;W. Lencer;M. Jobling;A. Kenworthy
目前的脂筏模型认为，脂类结构域以纳米级的成分波动形式存在，这些波动可能会稳定在更大的结构域中，从而更好地划分细胞功能。然而，稳定筏的组装和功能的机制仍然不清楚。在这里，我们使用研究得很好的RAFT标记霍乱毒素B五聚体(CTxB)来测试糖脂交联作为RAFT靶向和排序机制的作用，它可以结合多达五个GM1糖鞘糖脂进入宿主细胞。我们发现，当应用于细胞来源的巨型质膜囊泡时，只包含一个功能GM1结合位点的CTxB变体与具有五个结合位点的野生型CTxB相比，向有序相的分配显著减少。此外，与野生型CTxB不同，单价CTxB不稳定膜结构域。这些结果支持了长期以来的假设，即CTxB通过脂质交联机制稳定RAFT结构域，并确立了交联剂在CTxB向有序结构域分配中的作用。
Current models of lipid rafts propose that lipid domains exist as nanoscale compositional fluctuations and these fluctuations can potentially be stabilized into larger domains, consequently better compartmentalizing cellular functions. However, the mechanisms governing stabilized raft assembly and function remain unclear. Here, we test the role of glycolipid crosslinking as a raft targeting and ordering mechanism using the well-studied raft marker cholera toxin B pentamer (CTxB) that binds up to five GM1 glycosphingolipids to enter host cells. We show that when applied to cell-derived giant plasma membrane vesicles, a variant of CTxB containing only a single functional GM1 binding site exhibits significantly reduced partitioning to the ordered phase compared to wild-type CTxB with five binding sites. Moreover, monovalent CTxB does not stabilize membrane domains, unlike wild-type CTxB. These results support the long-held hypothesis that CTxB stabilizes raft domains via a lipid crosslinking mechanism and establish a role for crosslinking in the partitioning of CTxB to ordered domains.