Biotechnology Center (BIOTEC), Technische Universität Dresden, Dresden, Germany.
Proc Natl Acad Sci U S A. 2012 Sep 18;109(38):15283-8. doi: 10.1073/pnas.1206953109. Epub 2012 Sep 4.
In the living cell, proteins are able to organize space much larger than their dimensions. In return, changes of intracellular space can influence biochemical reactions, allowing cells to sense their size and shape. Despite the possibility to reconstitute protein self-organization with only a few purified components, we still lack knowledge of how geometrical boundaries affect spatiotemporal protein patterns. Following a minimal systems approach, we used purified proteins and photolithographically patterned membranes to study the influence of spatial confinement on the self-organization of the Min system, a spatial regulator of bacterial cytokinesis, in vitro. We found that the emerging protein pattern responds even to the lateral, two-dimensional geometry of the membrane such that, as in the three-dimensional cell, Min protein waves travel along the longest axis of the membrane patch. This shows that for spatial sensing the Min system does not need to be enclosed in a three-dimensional compartment. Using a computational model we quantitatively analyzed our experimental findings and identified persistent binding of MinE to the membrane as requirement for the Min system to sense geometry. Our results give insight into the interplay between geometrical confinement and biochemical patterns emerging from a nonlinear reaction-diffusion system.
在活细胞中，蛋白质能够组织比其自身尺寸大得多的空间。反过来，细胞内空间的变化可以影响生化反应，使细胞能够感知自身的大小和形状。尽管仅用少数几种纯化的成分就能重新构建蛋白质的自组织，但我们仍然缺乏关于几何边界如何影响蛋白质时空图案形成的知识。我们采用最小系统方法，使用纯化的蛋白质和光刻图案化的膜来研究空间限制对 Min 系统（细菌胞分裂的空间调节剂）在体外自我组织的影响。我们发现，即使是膜的二维侧向几何形状也会影响到蛋白质图案的形成，从而使 Min 蛋白波沿着膜片的最长轴传播，就像在三维细胞中一样。这表明，对于空间感应，Min 系统不需要被封闭在三维隔室中。我们使用计算模型对实验结果进行了定量分析，并确定 MinE 与膜的持续结合是 Min 系统感知几何形状的要求。我们的研究结果深入了解了非线性反应扩散系统中几何约束和生化图案之间的相互作用。
