Cell division in all domains of life requires the orchestration of many proteins, but in Archaea most of the machinery remains poorly characterized. Here we investigate the FtsZ-based cell division mechanism in Haloferax volcanii and find proteins containing photosynthetic reaction centre (PRC) barrel domains that play an essential role in archaeal cell division. We rename these proteins cell division protein B 1 (CdpB1) and CdpB2. Depletions and deletions in their respective genes cause severe cell division defects, generating drastically enlarged cells. Fluorescence microscopy of tagged FtsZ1, FtsZ2 and SepF in CdpB1 and CdpB2 mutant strains revealed an unusually disordered divisome that is not organized into a distinct ring-like structure. Biochemical analysis shows that SepF forms a tripartite complex with CdpB1/2 and crystal structures suggest that these two proteins might form filaments, possibly aligning SepF and the FtsZ2 ring during cell division. Overall our results indicate that PRC-domain proteins play essential roles in FtsZ-based cell division in Archaea.

生命各个领域的细胞分裂都需要许多蛋白质的协调，但在古生菌中，大多数机制仍然知之甚少。在这里，我们研究了Haloferax volcanii中基于 FtsZ 的细胞分裂机制，并发现了含有光合反应中心 (PRC) 桶状结构域的蛋白质，这些结构域在古菌细胞分裂中发挥着重要作用。我们将这些蛋白质重命名为细胞分裂蛋白 B 1 (CdpB1) 和 CdpB2。各自基因的消耗和缺失会导致严重的细胞分裂缺陷，产生急剧增大的细胞。CdpB1 和 CdpB2 突变株中标记的 FtsZ1、FtsZ2 和 SepF 的荧光显微镜揭示了异常无序的分裂体，未组织成明显的环状结构。生化分析表明，SepF 与 CdpB1/2 形成三联复合物，晶体结构表明这两种蛋白可能形成丝状结构，可能在细胞分裂过程中使 SepF 和 FtsZ2 环对齐。总的来说，我们的结果表明 PRC 结构域蛋白在古细菌中基于 FtsZ 的细胞分裂中发挥着重要作用。