Morten Michael J, Gamsjaeger Roland, Cubeddu Liza, Kariawasam Ruvini, Peregrina Jose, Penedo J Carlos, White Malcolm F
Biomedical Sciences Research Complex, University of St Andrews, St Andrews, KY16 9ST, UK.
School of Science and Health, Western Sydney University, Locked Bag 1797, Penrith, NSW, 2751, Australia.
Extremophiles. 2017 Mar;21(2):369-379. doi: 10.1007/s00792-016-0910-2. Epub 2017 Jan 10.
Single-stranded DNA-binding proteins (SSBs), including replication protein A (RPA) in eukaryotes, play a central role in DNA replication, recombination, and repair. SSBs utilise an oligonucleotide/oligosaccharide-binding (OB) fold domain to bind DNA, and typically oligomerise in solution to bring multiple OB fold domains together in the functional SSB. SSBs from hyperthermophilic crenarchaea, such as Sulfolobus solfataricus, have an unusual structure with a single OB fold coupled to a flexible C-terminal tail. The OB fold resembles those in RPA, whilst the tail is reminiscent of bacterial SSBs and mediates interaction with other proteins. One paradigm in the field is that SSBs bind specifically to ssDNA and much less strongly to RNA, ensuring that their functions are restricted to DNA metabolism. Here, we use a combination of biochemical and biophysical approaches to demonstrate that the binding properties of S. solfataricus SSB are essentially identical for ssDNA and ssRNA. These features may represent an adaptation to a hyperthermophilic lifestyle, where DNA and RNA damage is a more frequent event.
单链DNA结合蛋白（SSB），包括真核生物中的复制蛋白A（RPA），在DNA复制、重组和修复中起着核心作用。SSB利用寡核苷酸/寡糖结合（OB）折叠结构域结合DNA，并且通常在溶液中寡聚化，以使多个OB折叠结构域在功能性SSB中聚集在一起。来自嗜热泉古菌的SSB，如嗜热栖热菌，具有不寻常的结构，其单个OB折叠与灵活的C末端尾巴相连。OB折叠类似于RPA中的那些，而尾巴让人联想到细菌SSB，并介导与其他蛋白质的相互作用。该领域的一个范例是SSB特异性结合单链DNA，而与RNA的结合则弱得多，从而确保其功能仅限于DNA代谢。在这里，我们结合使用生化和生物物理方法来证明嗜热栖热菌SSB对单链DNA和单链RNA的结合特性基本相同。这些特征可能代表了对嗜热生活方式的一种适应，在这种生活方式中，DNA和RNA损伤是更频繁发生的事件。
