Department of Chemistry, Gwangju Institute of Science and Technology, Gwangju 61005, Korea.
Department of Chemistry, University of Colorado Denver, Denver, CO 80217-3364, USA.
Int J Mol Sci. 2022 Mar 13;23(6):3099. doi: 10.3390/ijms23063099.
Proteins from , an extremophile, are active even at high temperatures. The single-stranded DNA (ssDNA) binding protein of (SsoSSB) is overexpressed to protect ssDNA during DNA metabolism. Although SsoSSB has the potential to be applied in various areas, its structural and ssDNA binding properties at high temperatures have not been studied. We present the solution structure, backbone dynamics, and ssDNA binding properties of SsoSSB at 50 °C. The overall structure is consistent with the structures previously studied at room temperature. However, the loop between the first two β sheets, which is flexible and is expected to undergo conformational change upon ssDNA binding, shows a difference from the ssDNA bound structure. The ssDNA binding ability was maintained at high temperature, but different interactions were observed depending on the temperature. Backbone dynamics at high temperature showed that the rigidity of the structured region was well maintained. The investigation of an N-terminal deletion mutant revealed that it is important for maintaining thermostability, structure, and ssDNA binding ability. The structural and dynamic properties of SsoSSB observed at high temperature can provide information on the behavior of proteins in thermophiles at the molecular level and guide the development of new experimental techniques.
来自嗜极生物的蛋白质即使在高温下也具有活性。（嗜热硫化叶菌）的单链 DNA（ssDNA）结合蛋白（SsoSSB）被过度表达以在 DNA 代谢过程中保护 ssDNA。尽管 SsoSSB 具有在各个领域应用的潜力，但它在高温下的结构和 ssDNA 结合特性尚未得到研究。我们展示了 SsoSSB 在 50°C 时的溶液结构、骨架动力学和 ssDNA 结合特性。整体结构与以前在室温下研究的结构一致。然而，在第一个两个β片层之间的环，它是灵活的，预计在 ssDNA 结合时会发生构象变化，与 ssDNA 结合结构不同。在高温下，ssDNA 结合能力得以保持，但观察到不同的相互作用取决于温度。高温下的骨架动力学表明，结构区域的刚性得到很好的保持。对 N 端缺失突变体的研究表明，它对于维持热稳定性、结构和 ssDNA 结合能力很重要。在高温下观察到的 SsoSSB 的结构和动态特性可以提供有关蛋白质在嗜热生物中分子水平行为的信息，并指导新实验技术的开发。
