Targeting the weakest links in DNA for selective structural recognition

针对 DNA 中最薄弱的环节进行选择性结构识别

• 批准号: BB/P021328/1
• 负责人: John Brazier
• 金额: $ 60.18万
• 依托单位: University of Reading
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2017
• 资助国家: 英国
• 起止时间: 2017 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=BB%2FP021328%2F1
• 关键词: Targeting; weakest; links; DNA; selective

Deoxyribonucleic acid (DNA) is unique for each individual, it is linked to genetic disease, and normally forms a double helix. DNA is made up of four bases - adenine (A), thymine (T), guanine (G) and cytosine (C), and with A pairing with T and G pairing with C to give the familiar long chain with a right-handed twist. Nucleic acids (DNA and RNA) can actually adopt a number of different structures, which are greatly dependent on the order of the four bases. The sequence of the bases has a profound effect on the shape and stability of the DNA chain, with specific base steps (e.g. thymine followed by adenine) more flexible than others. Ruthenium polypyridyl complexes are small molecules that have been shown to insert themselves between the bases of DNA and have been investigated for a variety of applications, from light activated anti-cancer therapy to the detection of base mismatches (in which the bases are paired with the incorrect partner and which are linked to the onset of several diseases). These ruthenium complexes are prepared as mixtures of two different molecules (known as enantiomers), that only differ by the direction of the components surrounding the ruthenium centre, like propellers which can turn either way, to the right (clockwise) or to the left (anticlockwise). Much of the research performed on the ruthenium complexes has used an equal mixture of the enantiomers (due to the difficulty in separating the two molecules from one another; they are chemically identical except for this property). Our recent research has shown that the interaction of ruthenium complexes to DNA is not straightforward, with each enantiomer capable of binding to the DNA in a different manner, which could limit their use in the applications mentioned above. We propose to combine our experience in X-ray crystallography (producing solid crystals of DNA and complex that can be used to understand the arrangement of the two components relative to each other) with a systematic study of binding to specific sequences of DNA. We will use enantiomerically pure ruthenium complexes (in which one of the enantiomers is completely separated from the other) to understand how each molecule binds, and the relationship between the two. Experiments conducted in our laboratory, involving crystallography and techniques in solution, have shown that both enantiomers seem to target and bind weakness in the DNA structure and sequence, but sometimes in different ways. This weakness can be in the form of DNA that has been damaged either by the presence of mismatches (where the bases pair with the wrong partner), breaks in the DNA strand, or the presence of bases damaged by environmental conditions (for example chemicals or radiation). Another interesting property of nucleic acids is that they can adopt different structures, distinct from the well known right-twisting double helix. The ability to specifically recognise these alternative structures of nucleic acids will allow us to understand their role within the body, and to develop ways of using them to combat disease. Two of these more specialised structures are the G-quadruplex and i-motif structure, which are four stranded assemblies of DNA that can be formed by specific sequences found in our genetic code. There is a growing body of evidence that suggests that these structures may play important roles in several processes in the body, and being able to target them and selectively stabilise or destabilise could lead to new treatment for diseases as diverse as diabetes to cancer. The proposed research is important in order to unlock the potential of the ruthenium complexes as anti-cancer drugs, or selective biological probes. We must carry out the proposed research to make sense of the way they bind and the effect they then have on the DNA structure and its behaviour in the test tube.

脱氧核糖核酸（DNA）对每个人来说都是独一无二的，它与遗传疾病有关，通常形成双螺旋。DNA由四种碱基组成-腺嘌呤（A），胸腺嘧啶（T），鸟嘌呤（G）和胞嘧啶（C），A与T配对，G与C配对，以产生熟悉的右手扭曲的长链。核酸（DNA和RNA）实际上可以采用许多不同的结构，这在很大程度上取决于四种碱基的顺序。碱基的顺序对DNA链的形状和稳定性有着深远的影响，特定的碱基步骤（例如胸腺嘧啶和腺嘌呤）比其他步骤更灵活。钌多吡啶复合物是小分子，已被证明可以将其插入DNA碱基之间，并已被研究用于各种应用，从光激活抗癌治疗到检测碱基错配（其中碱基与不正确的配偶体配对，并与几种疾病的发作有关）。这些钌络合物是由两种不同的分子（称为对映体）混合而成，它们的区别仅在于钌中心周围的成分的方向，就像螺旋桨一样，可以向右（顺时针）或向左（逆时针）旋转。对钌络合物进行的大部分研究都使用了对映异构体的等量混合物（由于难以将两个分子彼此分离;它们在化学上是相同的，除了这个性质）。我们最近的研究表明，钌配合物与DNA的相互作用并不简单，每种对映体都能够以不同的方式与DNA结合，这可能会限制它们在上述应用中的应用。我们建议将联合收割机在X射线晶体学（生产DNA和复合物的固体晶体，可用于了解两种组分相对于彼此的排列）方面的经验与DNA特定序列结合的系统研究相结合。我们将使用对映体纯的钌络合物（其中一种对映体与另一种完全分离）来了解每个分子如何结合，以及两者之间的关系。在我们实验室进行的实验，涉及晶体学和技术在溶液中，已经表明，这两种对映体似乎靶向和结合DNA结构和序列中的弱点，但有时以不同的方式。这种弱点可以是DNA的形式，这种DNA已经被破坏，或者是由于存在错配（碱基与错误的伴侣配对），DNA链断裂，或者是由于环境条件（例如化学品或辐射）破坏的碱基的存在。核酸的另一个有趣的特性是，它们可以采用不同的结构，与众所周知的右扭转双螺旋不同。特异性识别这些核酸替代结构的能力将使我们能够了解它们在体内的作用，并开发出利用它们对抗疾病的方法。其中两个更专门的结构是G-四链体和i-基序结构，它们是四股DNA组装体，可以由我们遗传密码中的特定序列形成。越来越多的证据表明，这些结构可能在体内的几个过程中发挥重要作用，能够靶向它们并选择性地稳定或不稳定可能导致从糖尿病到癌症等多种疾病的新治疗方法。这项研究对于释放钌配合物作为抗癌药物或选择性生物探针的潜力非常重要。我们必须进行拟议的研究，以了解它们结合的方式以及它们对DNA结构及其在试管中的行为的影响。