The E. coli single-stranded DNA-binding protein (SSB) is essential to viability. It plays key roles in DNA metabolism where it binds to nascent single strands of DNA and to target proteins known as the SSB interactome. There are >2,000 tetramers of SSB per cell with 100-150 associated with the genome at any one time, either at DNA replication forks or at sites of repair. The remaining 1,900 tetramers could constantly diffuse throughout the cytosol or be associated with the inner membrane as observed for other DNA metabolic enzymes. To visualize SSB localization and to ascertain potential spatiotemporal changes in response to DNA damage, SSB-GFP chimeras were visualized using a novel, super-resolution microscope optimized for the study of prokaryotic cells. In the absence of DNA damage, SSB localizes to a small number of foci and the excess protein is associated with the inner membrane where it binds to the major phospholipids. Within five minutes following DNA damage, the vast majority of SSB disengages from the membrane and is found almost exclusively in the cell interior. Here, it is observed in a large number of foci, in discreet structures or, in diffuse form spread over the genome, thereby enabling repair events.

中文翻译：

---

超分辨率成像揭示了响应DNA损伤的大肠杆菌SSB定位的变化。

大肠杆菌单链DNA结合蛋白（SSB）对生存能力至关重要。它在DNA代谢中起关键作用，它与新生的DNA单链结合并与称为SSB相互作用蛋白的靶蛋白结合。在任何时候，无论是在DNA复制叉还是在修复位点，每个细胞中有> 2,000个SSB四聚体，其中100-150个与基因组相关。其余的1,900个四聚体可能会不断扩散到整个细胞质中，或与内膜结合，就像其他DNA代谢酶所观察到的那样。为了可视化SSB定位并确定响应DNA损伤的潜在时空变化，使用一种为研究原核细胞而优化的新型超高分辨率显微镜对SSB-GFP嵌合体进行可视化。在没有DNA损伤的情况下，SSB定位于少量病灶，过量的蛋白质与内膜结合，并与主要的磷脂结合。DNA损伤后五分钟之内，绝大多数SSB从膜上脱离，几乎只存在于细胞内部。在这里，它以大量的病灶，离散的结构或散布在基因组上的形式被观察到，从而可以进行修复。