Most bacteria accomplish cell division with the help of a dynamic protein complex called the divisome, which spans the cell envelope in the plane of division. Assembly and activation of this machinery are coordinated by the tubulin-related GTPase FtsZ, which was found to form treadmilling filaments on supported bilayers in vitro¹, as well as in live cells, in which filaments circle around the cell division site^2,3. Treadmilling of FtsZ is thought to actively move proteins around the division septum, thereby distributing peptidoglycan synthesis and coordinating the inward growth of the septum to form the new poles of the daughter cells⁴. However, the molecular mechanisms underlying this function are largely unknown. Here, to study how FtsZ polymerization dynamics are coupled to downstream proteins, we reconstituted part of the bacterial cell division machinery using its purified components FtsZ, FtsA and truncated transmembrane proteins essential for cell division. We found that the membrane-bound cytosolic peptides of FtsN and FtsQ co-migrated with treadmilling FtsZ–FtsA filaments, but despite their directed collective behaviour, individual peptides showed random motion and transient confinement. Our work suggests that divisome proteins follow treadmilling FtsZ filaments by a diffusion-and-capture mechanism, which can give rise to a moving zone of signalling activity at the division site.

大多数细菌在称为分裂体的动态蛋白质复合物的帮助下完成细胞分裂，分裂体跨越分裂平面中的细胞包膜。这种机器的组装和激活由微管蛋白相关的 GTPase FtsZ 协调，该 GTPase FtsZ 被发现在体外¹以及在活细胞中形成跑步细丝，其中细丝围绕细胞分裂部位^2,3。FtsZ 的跑步被认为会主动移动蛋白质在分裂隔膜周围，从而分配肽聚糖合成并协调隔膜的向内生长以形成子细胞的新极⁴. 然而，这种功能背后的分子机制在很大程度上是未知的。在这里，为了研究 FtsZ 聚合动力学如何与下游蛋白质耦合，我们使用其纯化的成分 FtsZ、FtsA 和截断的细胞分裂所必需的跨膜蛋白重构了部分细菌细胞分裂机制。我们发现 FtsN 和 FtsQ 的膜结合细胞溶质肽与跑步机 FtsZ-FtsA 细丝共同迁移，但尽管它们具有定向的集体行为，但单个肽显示出随机运动和瞬时限制。我们的工作表明，分裂体蛋白通过扩散和捕获机制跟随跑步的 FtsZ 细丝，这可以在分裂部位产生一个信号活动的移动区。