Department of Crystallography and Structural Biology, Institute of Physical-Chemistry "Rocasolano", Spanish National Research Council (CSIC), Madrid, Spain.
Department of Chemistry, Biotechnology, and Food Science, Norwegian University of Life Sciences, Ås, Norway.
mBio. 2020 Sep 1;11(5):e01488-20. doi: 10.1128/mBio.01488-20.
FtsEX is a membrane complex widely conserved across diverse bacterial genera and involved in critical processes such as recruitment of division proteins and in spatial and temporal regulation of muralytic activity during cell division or sporulation. FtsEX is a member of the ABC transporter superfamily. The component FtsX is an integral membrane protein, whereas FtsE is an ATPase and is required for the transmission of a conformational signal from the cytosol through the membrane to regulate the activity of cell wall hydrolases in the periplasm. Both proteins are essential in the major human respiratory pathogenic bacterium , and FtsX interacts with the modular peptidoglycan hydrolase PcsB at the septum. Here, we report high-resolution structures of pneumococcal FtsE bound to different nucleotides. Structural analysis revealed that FtsE contains all the conserved structural motifs associated with ATPase activity and afforded interpretation of the dimeric arrangement in both the ADP and ATP states. Interestingly, three specific FtsE regions with high structural plasticity were identified that shape the cavity in which the cytosolic region of FtsX would be inserted. The residues corresponding to the FtsX coupling helix, responsible for contacting FtsE, were identified and validated by mutagenesis studies showing that this interaction is essential for cell growth and proper morphology. Bacterial cell division is a central process that requires exquisite orchestration of both the cell wall biosynthetic and lytic machineries. The essential membrane complex FtsEX, widely conserved across bacteria, plays a central role by recruiting proteins to the divisome apparatus and by regulating periplasmic muralytic activity from the cytosol. FtsEX is a member of the type VII family of the ABC-superfamily, but instead of being a transporter, it couples the ATP hydrolysis catalyzed by FtsE to mechanically transduce a conformational signal that provokes the activation of peptidoglycan (PG) hydrolases. So far, no structural information is available for FtsE. Here, we provide the structural characterization of FtsE, confirming its ATPase nature and revealing regions with high structural plasticity which are key for FtsE binding to FtsX. The complementary binding region in FtsX has also been identified and validated Our results provide evidence on how the difference between the ATP/ADP-bound states in FtsE would dramatically alter the interaction of FtsEX with the PG hydrolase PcsB in pneumococcal division.
FtsEX 是一种广泛存在于不同细菌属中的膜复合物，参与关键过程，如招募分裂蛋白，并在细胞分裂或孢子形成期间时空调节壁水解酶的活性。FtsEX 是 ABC 转运蛋白超家族的成员。组成部分 FtsX 是一种完整的膜蛋白，而 FtsE 是一种 ATP 酶，对于将构象信号从细胞质传递通过膜以调节周质中细胞壁水解酶的活性是必需的。这两种蛋白质在主要的人类呼吸道致病菌中都是必不可少的，并且 FtsX 与隔膜处的模块化肽聚糖水解酶 PcsB 相互作用。在这里，我们报告了与不同核苷酸结合的肺炎链球菌 FtsE 的高分辨率结构。结构分析表明，FtsE 包含与 ATP 酶活性相关的所有保守结构基序，并解释了在 ADP 和 ATP 状态下的二聚体排列。有趣的是，确定了三个具有高结构可塑性的特定 FtsE 区域，这些区域塑造了 FtsX 的细胞质区域插入的腔。对应于 FtsX 偶联螺旋的残基，负责与 FtsE 接触，通过突变研究得到鉴定和验证，表明这种相互作用对于细胞生长和适当的形态是必不可少的。细菌细胞分裂是一个需要对细胞壁生物合成和裂解机制进行精确协调的核心过程。广泛存在于细菌中的必需膜复合物 FtsEX 通过将蛋白质招募到分裂体装置并从细胞质调节周质壁水解酶活性，发挥核心作用。FtsEX 是 ABC 超家族的 VII 型家族的成员，但它不是一种转运蛋白，而是将 FtsE 催化的 ATP 水解与机械转导构象信号偶联，该信号引发肽聚糖（PG）水解酶的激活。到目前为止，尚无关于 FtsE 的结构信息。在这里，我们提供了 FtsE 的结构特征，证实了其 ATP 酶性质，并揭示了具有高结构可塑性的区域，这些区域对于 FtsE 与 FtsX 的结合至关重要。FtsX 中的互补结合区域也已被确定和验证。我们的结果提供了证据，说明 FtsE 中 ATP/ADP 结合状态之间的差异如何在肺炎球菌分裂中极大地改变 FtsEX 与 PG 水解酶 PcsB 的相互作用。
