Some filamentous cyanobacteria are phototrophic bacteria with a true multicellular life style. They show patterned cell differentiation with the distribution of metabolic tasks between different cell types. This life style requires a system of cell-cell communication and metabolite exchange along the filament. During our study of the cell wall of species Nostoc punctiforme and Anabaena sp. PCC 7120 we discovered regular perforations in the septum between neighboring cells, which we called nanopore array. AmiC-like amidases are drilling the nanopores with a diameter of 20 nm, and are essential for communication and cell differentiation. NlpD-like regulators of AmiC activity and septum localized proteins SepJ, FraC and FraD are also involved in correct nanopore formation. By focused ion beam (FIB) milling and electron cryotomography we could visualize the septal junctions, which connect adjacent cells and pass thru the nanopores. They consist of cytoplasmic caps, which are missing in the fraD mutant, a plug inside the cytoplasmic membrane and a tube like conduit. A destroyed proton motive force and other stress factors lead to a conformational change in the cap structure and loss of cell-cell communication. These gated septal junctions of cyanobacteria are ancient structures that represent an example of convergent evolution, predating metazoan gap junctions.

一些丝状蓝细菌是具有真正多细胞生活方式的光养细菌。它们显示了模式化的细胞分化以及不同细胞类型之间新陈代谢任务的分布。这种生活方式需要沿着细丝的细胞间通讯和代谢物交换系统。在我们研究点状念珠菌和鱼腥藻细胞壁的过程中sp。PCC 7120我们在相邻细胞之间的间隔中发现了规则的穿孔，我们称其为纳米孔阵列。像AmiC一样的酰胺酶正在钻直径20 nm的纳米孔，这对于通讯和细胞分化是必不可少的。AmiC活性的NlpD样调节剂和隔垫局部蛋白SepJ，FraC和FraD也参与正确的纳米孔形成。通过聚焦离子束（FIB）铣削和电子低温断层照相术，我们可以观察到隔室连接处，其连接相邻的细胞并穿过纳米孔。它们由胞质帽组成，在fraD中缺失突变体，细胞质膜内的塞子和类似导管的管子。破坏的质子动力和其他应力因素导致帽结构的构象变化和细胞间通讯的丧失。蓝细菌的这些门控的隔片交界处是古老的结构，代表了会聚进化的一个例子，早于后生间隙交界处。