FtsQBL是大肠杆菌分裂体中的跨膜蛋白复合物,在调节细胞分裂中起关键作用。尽管已经做出了广泛的努力来研究这三种相关蛋白质之间的相互作用,FtsQ,FTSB,和FtsL,详细的相互作用机制仍然知之甚少。在这项研究中,我们使用氢-氘交换质谱来研究这些全长蛋白质及其复合物。我们还解剖了复合物中的结构动态变化和相关的结合界面。我们的数据显示,FtsB和FtsL在周质和跨膜区相互作用,形成稳定的复合物。此外,FtsB的周质区域发生了明显的构象变化。在计算建模的帮助下,我们的结果表明,FtsBL复合可能会使各自的收缩控制域(CCD)紧密靠近。我们证明,当FtsBL采用卷曲螺旋结构时,CCD相对于膜表面固定在垂直位置;因此,这种构象变化可能是FtsBL与其他分裂体蛋白相互作用所必需的。在FtsQBL复合体中,有趣的是,我们只显示了FtsB在其C端区域与FtsQ相互作用,这加强了FtsQ的β结构域的大面积。与此一致,我们发现FtsQ中的α-和β-结构域之间的联系在复合物中也得到了加强。总的来说,本研究提供了重要的实验证据,详细说明了全长FtsB之间的局部相互作用,FtsL,和FtsQ蛋白,以及对FtsQBL络合在调节分裂体活性中的作用的宝贵见解。
FtsQBL is a transmembrane protein complex in the
divisome of Escherichia coli that plays a critical role in regulating cell division. Although extensive efforts have been made to investigate the interactions between the three involved proteins, FtsQ, FtsB, and FtsL, the detailed interaction mechanism is still poorly understood. In this study, we used hydrogen-deuterium exchange mass spectrometry to investigate these full-length proteins and their complexes. We also dissected the structural dynamic changes and the related binding interfaces within the complexes. Our data revealed that FtsB and FtsL interact at both the periplasmic and transmembrane regions to form a stable complex. Furthermore, the periplasmic region of FtsB underwent significant conformational changes. With the help of computational modeling, our results suggest that FtsBL complexation may bring the respective constriction control domains (CCDs) in close proximity. We show that when FtsBL adopts a coiled-coil structure, the CCDs are fixed at a vertical position relative to the membrane surface; thus, this conformational change may be essential for FtsBL\'s interaction with other
divisome proteins. In the FtsQBL complex, intriguingly, we show only FtsB interacts with FtsQ at its C-terminal region, which stiffens a large area of the β-domain of FtsQ. Consistent with this, we found the connection between the α- and β-domains in FtsQ is also strengthened in the complex. Overall, the present study provides important experimental evidence detailing the local interactions between the full-length FtsB, FtsL, and FtsQ protein, as well as valuable insights into the roles of FtsQBL complexation in regulating
divisome activity.