The calcium-dependent and calcium-independent membrane binding of synaptotagmin 1: two modes of C2B binding.
The calcium-dependent and calcium-independent membrane binding of synaptotagmin 1: two modes of C2B binding.
复制标题
DOI：
10.1016/j.jmb.2009.01.064
复制
发表时间：
2009-03-27
影响因子：
5.6
通讯作者：
Cafiso, David S.
中科院分区：
文献类型：
--
作者：
Kuo, Weiwei;Herrick, Dawn Z.;Ellena, Jeffrey F.;Cafiso, David S.
关键词：
使用定点自旋标记（SDSL）和囊泡沉降相结合的可溶性C2结构域从synaptotagmin 1（syt 1）的Ca 2+独立的膜相互作用的特点。syt 1的第二个C2结构域C2B以不依赖于Ca 2+的方式与含有磷脂酰丝氨酸（PS）和磷脂酰胆碱（PC）的膜结合，脂质分配系数约为3.0 × 102 M−1。含有syt 1的第一和第二C2结构域C2 A和C2B的可溶性片段具有相似的亲和力，但在不存在Ca 2+的情况下，单独的C2 A对PC/PS双层没有可检测的亲和力。虽然C2B的Ca 2+非依赖性膜亲和力是适度的，但它表明该结构域在细胞内的溶液中永远不会游离。SDSL被用来获得双层深度限制，和模拟退火程序被用来生成一个模型的C2B的膜对接的情况下的Ca 2+。在该模型中，C2B的多碱基链形成了结构域的膜结合表面;然而，C2B的这一面并不穿透双层，而是在C2B结合时位于水性双层内。这种双层位置表明C2B以纯静电方式与双层界面相互作用。在Ca 2+存在下，C2B的膜亲和力增加约20倍，并且结构域旋转，使得C2B的Ca 2+结合环插入双层中。这种Ca 2+触发的构象变化可能作为一个开关，以调节C2B的多元面的可访问性，并控制syt 1与融合机器的其他组件的相互作用。
The Ca2+-independent membrane interactions of the soluble C2 domains from synaptotagmin 1 (syt1) were characterized using a combination of site-directed spin labeling (SDSL) and vesicle sedimentation. The second C2 domain of syt1, C2B, binds to membranes containing phosphatidylserine (PS) and phosphatidylcholine (PC) in a Ca2+-independent manner with a lipid partition coefficient of approximately 3.0 × 102 M−1. A soluble fragment containing the first and second C2 domains of syt1, C2A and C2B, has a similar affinity, but C2A alone has no detectable affinity to PC/PS bilayers in the absence of Ca2+. Although the Ca2+-independent membrane affinity of C2B is modest, it indicates that this domain will never be free in solution within the cell. SDSL was used to obtain bilayer depth restraints, and a simulated annealing routine was used to generate a model for the membrane docking of C2B in the absence of Ca2+. In this model, the polybasic strand of C2B forms the membrane binding surface for the domain; however, this face of C2B does not penetrate the bilayer, but is localized within the aqueous double-layer when C2B is bound. This double-layer location indicates that C2B interacts in a purely electrostatic manner with the bilayer interface. In the presence of Ca2+, the membrane affinity of C2B is increased approximately 20 fold, and the domain rotates so that the Ca2+ binding loops of C2B insert into the bilayer. This Ca2+-triggered conformational change may act as a switch to modulate the accessibility of the polybasic face of C2B, and control interactions of syt1 with other components of the fusion machinery.
登录
查看更多内容
影响因子：
16.8
作者：
Araç, D;Chen, XC;Rizo, J
通讯作者：
Rizo, J
影响因子：
16.8
作者：
Bhalla, A;Chicka, MC;Chapman, ER
通讯作者：
Chapman, ER
影响因子：
8
作者：
Guo, Zhefeng;Cascio, Duilio;Hubbell, Wayne L.
通讯作者：
Hubbell, Wayne L.
影响因子：
3.4
作者：
BenTal, N;Honig, B;McLaughlin, S
通讯作者：
McLaughlin, S
影响因子：
56.9
作者：
BROSE, N;PETRENKO, AG;JAHN, R
通讯作者：
JAHN, R