MRC Laboratory of Molecular Biology, Cambridge, UK.
EMBO J. 2012 May 16;31(10):2249-60. doi: 10.1038/emboj.2012.76. Epub 2012 Mar 30.
FtsA is an early component of the Z-ring, the structure that divides most bacteria, formed by tubulin-like FtsZ. FtsA belongs to the actin family of proteins, showing an unusual subdomain architecture. Here we reconstitute the tethering of FtsZ to the membrane via FtsA's C-terminal amphipathic helix in vitro using Thermotoga maritima proteins. A crystal structure of the FtsA:FtsZ interaction reveals 16 amino acids of the FtsZ tail bound to subdomain 2B of FtsA. The same structure and a second crystal form of FtsA reveal that FtsA forms actin-like protofilaments with a repeat of 48 Å. The identical repeat is observed when FtsA is polymerized using a lipid monolayer surface and FtsAs from three organisms form polymers in cells when overexpressed, as observed by electron cryotomography. Mutants that disrupt polymerization also show an elongated cell division phenotype in a temperature-sensitive FtsA background, demonstrating the importance of filament formation for FtsA's function in the Z-ring.
FtsA 是 Z 环的早期组成部分，Z 环是大多数细菌分裂的结构，由微管蛋白样 FtsZ 形成。FtsA 属于肌动蛋白家族的蛋白质，表现出一种不寻常的亚结构域架构。在这里，我们使用海洋栖热菌蛋白在体外重建了 FtsA 通过其 C 端两亲性螺旋将 FtsZ 固定在膜上的方式。FtsA:FtsZ 相互作用的晶体结构揭示了 FtsZ 尾部的 16 个氨基酸结合到 FtsA 的亚结构域 2B。相同的结构和 FtsA 的第二种晶体形式表明 FtsA 形成具有 48Å 重复的肌动蛋白样原丝。当使用脂质单层表面聚合 FtsA 时以及当过表达时，在三种生物体中 FtsA 形成聚合物时观察到相同的重复，如电子 cryotomography 观察到的那样。破坏聚合的突变体在温度敏感的 FtsA 背景下也表现出细胞分裂拉长的表型，这表明丝状形成对于 FtsA 在 Z 环中的功能很重要。
