Bacterial Cell Biology & Physiology, Swammerdam Institute for Life Science, Faculty of Science, University of Amsterdam, Amsterdam, The Netherlands.
Centre for Bacterial Cell Biology, Biosciences Institute, Newcastle University, Newcastle upon Tyne, United Kingdom.
PLoS Genet. 2020 Dec 28;16(12):e1009276. doi: 10.1371/journal.pgen.1009276. eCollection 2020 Dec.
Rod-shape of most bacteria is maintained by the elongasome, which mediates the synthesis and insertion of peptidoglycan into the cylindrical part of the cell wall. The elongasome contains several essential proteins, such as RodA, PBP2, and the MreBCD proteins, but how its activities are regulated remains poorly understood. Using E. coli as a model system, we investigated the interactions between core elongasome proteins in vivo. Our results show that PBP2 and RodA form a complex mediated by their transmembrane and periplasmic parts and independent of their catalytic activity. MreC and MreD also interact directly with PBP2. MreC elicits a change in the interaction between PBP2 and RodA, which is suppressed by MreD. The cytoplasmic domain of PBP2 is required for this suppression. We hypothesize that the in vivo measured PBP2-RodA interaction change induced by MreC corresponds to the conformational change in PBP2 as observed in the MreC-PBP2 crystal structure, which was suggested to be the "on state" of PBP2. Our results indicate that the balance between MreC and MreD determines the activity of PBP2, which could open new strategies for antibiotic drug development.
大多数细菌的杆状形状是由伸长体维持的，它介导肽聚糖合成和插入细胞壁的圆柱形部分。伸长体包含几种必需的蛋白质，如 RodA、PBP2 和 MreBCD 蛋白，但它的活性如何调节仍知之甚少。我们使用大肠杆菌作为模型系统，在体内研究了核心伸长体蛋白之间的相互作用。我们的结果表明，PBP2 和 RodA 形成一个复合物，由它们的跨膜和周质部分介导，不依赖于它们的催化活性。MreC 和 MreD 也与 PBP2 直接相互作用。MreC 引起 PBP2 与 RodA 之间相互作用的变化，这种变化被 MreD 抑制。PBP2 的细胞质结构域是这种抑制所必需的。我们假设 MreC 诱导的体内测量的 PBP2-RodA 相互作用变化与在 MreC-PBP2 晶体结构中观察到的 PBP2 的构象变化相对应，这被认为是 PBP2 的“开启状态”。我们的结果表明，MreC 和 MreD 之间的平衡决定了 PBP2 的活性，这可能为抗生素药物开发开辟新的策略。
