Thompson Connor J, Vu Vinh H, Leckband Deborah E, Schwartz Daniel K
Department of Chemical and Biological Engineering , University of Colorado Boulder , Boulder 80309 , Colorado , United States.
J Phys Chem Lett. 2019 Aug 15;10(16):4528-4534. doi: 10.1021/acs.jpclett.9b01500. Epub 2019 Jul 29.
While both and (adhesive)-interactions cooperate in the assembly of intercellular adhesions, computational simulations have predicted that two-dimensional confinement may promote -oligomerization, in the absence of -interactions. Here, single-molecule tracking of cadherin extracellular domains on supported lipid bilayers revealed the density-dependent formation of oligomers and -clusters in the absence of -interactions. Lateral oligomers were virtually eliminated by mutating a putative (lateral) binding interface. At low cadherin surface coverage, wild-type and mutant cadherin diffused rapidly, consistent with the motion of a lipid molecule within a cadherin-free supported bilayer and with cadherins diffusing as monomers. Although the diffusion of mutant cadherin did not change appreciably with increasing surface coverage, the average short-time diffusion coefficient of wild-type cadherin slowed significantly above a fractional surface coverage of ∼0.01 (∼1100 molecules/μm). A detailed analysis of molecular trajectories suggested the presence of a broad size distribution of -cadherin oligomers. These findings verify predictions that two-dimensional confinement promotes -oligomerization, in the absence of -interactions.
虽然[具体内容1]和（黏附性的）相互作用在细胞间黏附的组装中协同作用，但计算模拟预测，在没有[具体内容2]相互作用的情况下，二维限制可能会促进[具体内容1]寡聚化。在这里，对支持脂质双分子层上钙黏蛋白细胞外结构域的单分子追踪揭示了在没有[具体内容2]相互作用的情况下，寡聚体和[具体内容1]簇的密度依赖性形成。通过突变一个假定的（横向）结合界面，横向寡聚体几乎被消除。在低钙黏蛋白表面覆盖率下，野生型和突变型钙黏蛋白快速扩散，这与无钙黏蛋白的支持双分子层中脂质分子的运动一致，也与作为单体扩散的钙黏蛋白一致。尽管突变型钙黏蛋白的扩散随着表面覆盖率的增加没有明显变化，但野生型钙黏蛋白的平均短时间扩散系数在表面覆盖率分数约为0.01（约1100个分子/μm）以上时显著减慢。对分子轨迹的详细分析表明存在广泛尺寸分布的[具体内容1] -钙黏蛋白寡聚体。这些发现证实了在没有[具体内容2]相互作用的情况下二维限制促进[具体内容1]寡聚化的预测。
