Investigating the stability and function of i-motif DNA

假设DNA以双螺旋形式存在，这种结构最早由沃森和克里克在1953年描述。然而，鲜为人知的是，DNA可以采用许多不同类型的结构。DNA是由四种不同的“积木”组成的，称为碱基：腺嘌呤，鸟嘌呤，胸腺嘧啶和胞嘧啶。富含胞嘧啶的DNA序列可以形成称为i-motifs的替代二级结构，首次发现于1993年。这种类型的序列在我们的基因组中广泛存在，可能在基因表达中发挥作用，但仍有许多基本问题没有得到解答。i基序结构的稳定性高度依赖于特定的碱基序列。为了了解哪些序列更有可能在生物学中形成i基序，需要了解它们的稳定性。该项目提出了一个系统的调查不同的DNA序列库，以确定稳定的i-基序形成的最佳序列要求。这将使我们能够定义规则来预测基于DNA序列类型的i基序结构的稳定性。然后，我们将使用这些信息对人类基因组进行计算分析，以估计可能形成i基序结构的序列的数量，以及这些序列在人类基因组中的位置。使用分子生物学技术的混合物，我们将调查的影响，稳定的i-基序结构的转录和去卷积的i-基序和G-四链体（结构，以前已经很好地表征）的动态之间的相互作用对基因表达。这一建议将揭示哪些i基序序列是最稳定的，并可能成为药物设计、治疗和结构研究的新靶点。

It is assumed that DNA exists as a double helix, the structure first described by Watson and Crick in 1953. However, it is lesser-known that DNA can adopt many different types of structure. DNA is composed of four different "building blocks" called bases: adenine, guanine, thymine and cytosine. DNA sequences rich in cytosine can form alternative secondary structures called i-motifs, first discovered in 1993. Sequences of this type are widespread throughout our genome and may play a role in gene expression, but there are many fundamental questions unanswered. The stability of i-motif structures is highly dependent on the particular sequence of bases. To understand which sequences are more likely to form i-motifs in biology, an understanding of their stability is required. This project proposes a systematic investigation of a library of different DNA sequences to determine the optimum sequence requirements for stable i-motif formation. This will allow us to define rules to predict the stability of i-motif structure based on the type of DNA sequence. We will then use this information for computational analysis of the human genome to estimate the number of sequences which could potentially form i-motif structures, and where these reside in the human genome. Using a mixture of molecular biology techniques, we will investigate the impact of stabilisation of i-motif structure on transcription and de-convolute the interplay between the dynamics of i-motifs and G-quadruplexes (structures which have previously been well-characterised) on gene expression. This proposal will reveal which i-motif sequences are most stable and potentially new targets for drug design, therapeutics and structural investigation.