Lifetime measurements reveal kinetic differences between homophilic cadherin bonds
Lifetime measurements reveal kinetic differences between homophilic cadherin bonds
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DOI：
10.1529/biophysj.105.069583
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发表时间：
2006-02-01
影响因子：
3.4
通讯作者：
Leckband, D
中科院分区：
文献类型：
--
作者：
Bayas, MV;Leung, A;Leckband, D
钙粘蛋白是一种多结构域的粘附蛋白，其相互作用在组织发生过程中指导细胞分选。它们确定细胞粘附特异性，但先前的研究未能确定可能成为细胞分选基础的物理差异。这些单分子研究确定了不同钙粘蛋白之间的动力学和强度差异。他们进一步证明了裂解阶段C-钙粘蛋白的模块化细胞外结构支持多态结合机制。这些多重键表现出映射到不同钙粘蛋白结构域的强度的动力学层次结构。C-cadherin的两个N端结构域形成两种结合状态，解离速率为3.9和0.02 s（-1）。后者比相应的上皮钙粘蛋白片段之间慢25倍。除了两个快速键外，五结构域片段（CEC 1 -5）还形成了另外两个更强、寿命更长的键，解离速率分别为0.00039和0.00001 s（-1）。我们进一步量化了受到恒定力的键的寿命，从而确定了多个解离事件，其速率与力谱数据定量一致。定性特征与上皮钙粘蛋白的定性特征相似。然而，显着差异的解离速率的外部域，其中包括特异性决定区，表明动力学差异可能决定钙粘蛋白的歧视，而不是粘附能。
Cadherins are multidomain adhesion proteins whose interactions direct cell sorting during histogenesis. They determine cell adhesion specificity, but prior studies failed to identify physical differences that could underlie cell sorting. These single molecule studies identify kinetic and strength differences between different cadherins. They further demonstrate that the modular extracellular architecture of cleavage stage C-cadherin supports a multistate binding mechanism. These multiple bonds exhibit a kinetic hierarchy of strengths that map to the different cadherin domains. The outer two N-terminal domains of C-cadherin form two bound states with dissociation rates of 3.9 and 0.02 s(-1). The latter is 25-fold slower than between the corresponding epithelial cadherin segments. In addition to the two fast bonds, the five-domain fragment ( CEC1-5) forms two additional stronger, longer-lived bonds with dissociation rates of 0.00039 and 0.00001 s(-1). We further quantified the lifetimes of bonds subject to a constant force, and thus identified multiple dissociation events with rates that agree quantitatively with the force spectroscopy data. The qualitative features are similar to those reported for epithelial cadherin. However, the significant differences in the dissociation rates of the outer domains, which include the specificity-determining region, suggest that kinetic differences may determine cadherin discrimination, rather than adhesion energies.