Structural Characterization of the Essential Cell Division Protein FtsE and Its Interaction with FtsX in Streptococcus pneumoniae
Structural Characterization of the Essential Cell Division Protein FtsE and Its Interaction with FtsX in Streptococcus pneumoniae
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DOI：
10.1128/mbio.01488-20
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发表时间：
2020-09-01
期刊：
影响因子：
6.4
通讯作者：
Hermoso, Juan A.
中科院分区：
文献类型：
--
作者：
Alcorlo, Martin;Straume, Daniel;Hermoso, Juan A.
FtsEX是一种膜复合体，广泛存在于不同的细菌属中，参与细胞分裂或孢子形成过程中的关键过程，如分裂蛋白的募集和溶壁活性的时空调节。FtsEX是ABC转运蛋白超家族的成员。组分FtsX是一种完整的膜蛋白，而FTSE是一种ATPase，它是从胞浆通过膜传递构象信号以调节周质中细胞壁水解酶活性所必需的。这两种蛋白在主要的人类呼吸道致病细菌肺炎链球菌中都是敏感的，FtsX在隔膜与模块化的肽聚糖水解酶PCSB相互作用。在这里，我们报告了肺炎球菌FTSE与不同核苷酸结合的高分辨率结构。结构分析表明，FTSE包含所有与ATPase活性相关的保守结构基序，并解释了ADP和ATP状态下的体内二聚体排列。有趣的是，确定了三个具有高结构可塑性的特定FTSE区域，它们形成了FtsX的胞浆区将被插入的空腔。体内突变研究表明，这种相互作用对细胞生长和正确的形态是必不可少的，与FtsX偶联螺旋相对应的残基负责接触FTSE。重要的细菌细胞分裂是一个中心过程，需要对细胞壁的生物合成和裂解机制进行精细的协调。在细菌中广泛保守的基本膜复合体FtsEX通过将蛋白质招募到分裂体器和调节胞浆中的周质溶壁活性而发挥核心作用。FtsEX是ABC-超家族中VII型家族的成员，但它不是转运蛋白，而是偶联由FTSE催化的ATP水解酶，机械地转导一个构象信号，激发肽聚糖(PG)水解酶的激活。到目前为止，还没有关于富时指数的结构性信息。在这里，我们提供了FTSE的结构特征，证实了它的ATPase性质，并揭示了结构可塑性高的区域，这些区域是FTSE与FtsX结合的关键。FtsX中的互补结合区也已被鉴定并在体内得到验证。我们的结果为FTSE中ATP/ADP结合状态之间的差异如何极大地改变FtsEX与肺炎球菌分裂中PG水解酶PCSB的相互作用提供了证据。
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 es-sential in the major human respiratory pathogenic bacterium Streptococcus pneumoniae, 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 in vivo 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 in vivo mutagenesis studies showing that this interaction is essential for cell growth and proper morphology.IMPORTANCE 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 in vivo. 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.