FtsZ, a tubulin‐like GTPase, is essential for bacterial cell division. In the presence of GTP, FtsZ polymerizes into filamentous structures, which are key to generating force in cell division. However, the structural basis for the molecular mechanism underlying FtsZ function remains to be elucidated. In this study, crystal structures of the enzymatic domains of FtsZ from Klebsiella pneumoniae (KpFtsZ) and Escherichia coli (EcFtsZ) were determined at 1.75 and 2.50 Å resolution, respectively. Both FtsZs form straight protofilaments in the crystals, and the two structures adopted relaxed (R) conformations. The T3 loop, which is involved in GTP/GDP binding and FtsZ assembly/disassembly, adopted a unique open conformation in KpFtsZ, while the T3 loop of EcFtsZ was partially disordered. The crystal structure of EcFtsZ can explain the results from previous functional analyses using EcFtsZ mutants.

中文翻译：

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肺炎克雷伯菌和大肠杆菌细胞分裂蛋白 FtsZ 的晶体结构。

FtsZ 是一种微管蛋白样 GTP 酶，对于细菌细胞分裂至关重要。在 GTP 存在的情况下，FtsZ 聚合成丝状结构，这是产生细胞分裂力的关键。然而，FtsZ 功能的分子机制的结构基础仍有待阐明。在本研究中，分别以 1.75 和 2.50 Å 的分辨率测定了肺炎克雷伯菌(KpFtsZ) 和大肠杆菌(EcFtsZ)的 FtsZ 酶结构域的晶体结构。两种 FtsZ 在晶体中形成直的原丝，并且两种结构均采用松弛 (R) 构象。KpFtsZ 中参与 GTP/GDP 结合和 FtsZ 组装/分解的 T3 环采用独特的开放构象，而 EcFtsZ 的 T3 环部分无序。EcFtsZ 的晶体结构可以解释之前使用 EcFtsZ 突变体进行功能分析的结果。