Septin assembly and membrane organization

细胞形态与细胞功能密切相关。细胞的骨架被称为细胞骨架，它是由聚合物网络组成的，它驱动形状的变化。细胞骨架的动态组装和重排允许细胞在时间和空间上对特定信号做出反应。细胞面临的一个根本挑战是，细胞骨架的分子比整个细胞的大小小得多。这个项目的一个目标是了解有关规模的信息是如何在细胞中传递的，这样小的积木(纳米大小)就可以进行更大数量级的形状变化。这项工作将揭示细胞骨架一部分的比例蓝图。这些实验将确定以不同的排列和模式聚集在一起的细丝构建的结构如何导致细胞形状和功能的差异。这项工作很重要，因为它将揭示生命系统中自组装的基本原理。了解这些原理对于设计合成细胞是至关重要的，这些细胞可能会被用来解决当前和未来的各种问题，如计算、生物能源或生物修复。Septin细胞骨架是一种特别强大的聚合物网络，可以分析细胞如何缩放和塑造蛋白质结构，因为Septin在细胞中组装成不同的形式。根据细胞环境的不同，Septin细丝可以编织成束、纱布、环和格子。这些不同的形状大小可以是数百纳米到微米。在许多情况下，这些组件形成在膜表面，在那里它们起到支架和膜屏障的作用。人们还不知道如何从相同的隔膜细丝的基本结构块中构建出如此不同几何形状和大小的组件。这项研究的目标是解决细胞如何调节间隔蛋白来构建形式和功能多样的结构。这些目标将通过生物物理方法、光遗传学和无细胞重建来实现。将采用尖端的定量成像，包括单分子和偏振荧光显微镜、高速原子力显微镜以及细胞自由重组和数学建模。间隔蛋白在真核生物中几乎无处不在，但在理解细胞如何从间隔蛋白细丝构建更高级别的结构方面存在重大差距。最终目标是理解变量函数是如何从形式上的变化中出现的。这里的实验解决了所有细胞在空间上如何组织的根本问题，因为有许多微米级组件的例子，这些组件是由纳米级的积木建造的。

Cell shape is intimately tied to cell function. The skeleton of a cell, called the cytoskeleton, is made of a network of polymers, which drive shape changes. The dynamic assembly and rearrangement of the cytoskeleton allow cells to react in both time and space to specific signals. A fundamental challenge for a cell is that the molecules of the cytoskeleton are much smaller than the size of the whole cell. A goal of this project is to understand how information about scale is transmitted in a cell so that small building blocks (nanometer in size) can carry out shape changes that are orders of magnitude larger. This work will reveal the scaling blueprint for one part of the cytoskeleton. The experiments will determine how structures built from filaments coming together in different arrangements and patterns leads to differences in cell shape and function. This work is important because it will reveal basic principals of self-assembly in living systems. Understanding these principals is essential to design synthetic cells that will likely be used for solving a variety of current and future problems such as in computing, bioenergy or bioremediation.The septin cytoskeleton is an especially powerful polymer network to analyze how cells scale and shape protein structures because septins assemble into diverse forms in cells. Septin filaments can be knit together into bundles, gauzes, rings and lattices depending on the cell context. These different forms can be hundreds of nanometers to micrometers in size. In many cases these assemblies form on membrane surfaces where they function as scaffolds and membrane barriers. It is not understood how assemblies of such varied geometry and size can be built out of the same fundamental building block of a septin filament. The objectives of this study address how cells regulate septins to build structures of versatile form and function. These objectives will be achieved through biophysical approaches, optogenetics and cell-free reconstitution. Cutting-edge, quantitative imaging will be employed including single-molecule and polarization fluorescence microscopy, high-speed atomic force microscopy together with cell free reconstitution and mathematical modeling. Septins are nearly ubiquitous in eukaryotes and yet there are major gaps in understanding how cells construct higher-order structures from septin filaments. The ultimate goal is to understand how variable function emerges from this variation in form. The experiments here address problems that are fundamental to how all cells are spatially organized as there are many examples of micrometer-scale assemblies that are built from nanometer-sized building blocks.