Freie Universität Berlin, Institut für Experimentalphysik, 14195 Berlin, Germany.
Bundesanstalt für Materialforschung und -prüfung (BAM), 12205 Berlin, Germany.
Phys Chem Chem Phys. 2020 Apr 6;22(13):6984-6992. doi: 10.1039/d0cp00092b.
Ectoine is a small zwitterionic osmolyte and compatible solute, which does not interfere with cell metabolism even at molar concentrations. Plasmid DNA (pUC19) was irradiated with ultraviolet radiation (UV-C at 266 nm) under quasi physiological conditions (PBS) and in pure water in the presence and absence of ectoine (THP(B)) and hydroxyectoine (THP(A)). Different types of UV induced DNA damage were analysed: DNA single-strand breaks (SSBs), abasic sites and cyclobutane pyrimidine dimers (CPDs). A complex interplay between these factors was observed with respect to the nature and occurrence of DNA damage with 266 nm photons. In PBS, the cosolutes showed efficient protection against base damage, whilst in pure water, a dramatic shift from SSB damage to base damage was observed when cosolutes were added. To test whether these effects are caused by ectoine binding to DNA, further experiments were conducted: small-angle X-ray scattering (SAXS), surface-plasmon resonance (SPR) measurements and Raman spectroscopy. The results show, for the first time, a close interaction between ectoine and DNA. This is in stark contrast to the assumption made by preferential exclusion models, which are often used to interpret the behaviour of compatible solutes within cells and with biomolecules. It is tentatively proposed that the alterations of UV damage to DNA are attributed to ectoine influence on nucleobases through the direct interaction between ectoine and DNA.
四氢嘧啶（ectoine）是一种小的两性离子渗透剂和相容溶质，即使在摩尔浓度下也不会干扰细胞代谢。质粒 DNA（pUC19）在准生理条件（PBS）和纯水中，在存在和不存在四氢嘧啶（THP(B)) 和羟基四氢嘧啶（THP(A)) 的情况下，用紫外线（UV-C 在 266nm）照射。分析了不同类型的 UV 诱导的 DNA 损伤：DNA 单链断裂（SSB）、无碱基位点和环丁烷嘧啶二聚体（CPD）。在 266nm 光子方面，观察到这些因素之间存在复杂的相互作用，涉及 DNA 损伤的性质和发生。在 PBS 中，共溶质对碱基损伤表现出有效的保护作用，而在纯水中，当添加共溶质时，从 SSB 损伤到碱基损伤的急剧转变。为了测试这些影响是否是由 ectoine 与 DNA 的结合引起的，进行了进一步的实验：小角 X 射线散射（SAXS）、表面等离子体共振（SPR）测量和拉曼光谱。结果首次表明，ectoine 与 DNA 之间存在密切的相互作用。这与优先排斥模型的假设形成鲜明对比，该模型常用于解释相容溶质在细胞内和与生物分子中的行为。初步提出，DNA 上的 UV 损伤的改变归因于 ectoine 通过与 DNA 的直接相互作用对核碱基的影响。
