Institut Pasteur, Department of Structural Biology and Chemistry, Laboratory for Bioorganic Chemistry of Nucleic Acids, CNRS UMR3523, 28, rue du Docteur Roux, 75724, Paris Cedex 15, France.
Université Paris Descartes, Sorbonne Paris Cité, 12 rue de l'École de Médecine, 75006, Paris, France.
Chembiochem. 2020 Dec 1;21(23):3398-3409. doi: 10.1002/cbic.202000402. Epub 2020 Sep 2.
Th formation of metal base pairs is a versatile method for the introduction of metal cations into nucleic acids that has been used in numerous applications including the construction of metal nanowires, development of energy, charge-transfer devices and expansion of the genetic alphabet. As an alternative, enzymatic construction of metal base pairs is an alluring strategy that grants access to longer sequences and offers the possibility of using such unnatural base pairs (UBPs) in SELEX experiments for the identification of functional nucleic acids. This method remains rather underexplored, and a better understanding of the key parameters in the design of efficient nucleotides is required. We have investigated the effect of methylation of the imidazole nucleoside (dIm TP) on the efficiency of the enzymatic construction of metal base pairs. The presence of methyl substituents on dImTP facilitates the polymerase-driven formation of dIm -Ag -dIm and dIm TP-Cr -dIm base pairs. Steric factors rather than the basicity of the imidazole nucleobase appear to govern the enzymatic formation of such metal base pairs. We also demonstrate the compatibility of other metal cations rarely considered in the construction of artificial metal bases by enzymatic DNA synthesis under both primer extension reaction and PCR conditions. These findings open up new directions for the design of nucleotide analogues for the development of metal base pairs.
金属碱基对的形成是将金属阳离子引入核酸的一种通用方法，已被广泛应用于构建金属纳米线、开发能源、电荷转移器件以及扩展遗传密码子等领域。作为替代方案，酶促构建金属碱基对是一种诱人的策略，它可以访问更长的序列，并提供在 SELEX 实验中使用这种非天然碱基对（UBP）来鉴定功能性核酸的可能性。然而，这种方法仍未得到充分探索，需要更好地了解在设计高效核苷酸时的关键参数。我们研究了咪唑核苷（dImTP）的甲基化对酶促构建金属碱基对效率的影响。dImTP 上的甲基取代基有助于聚合酶驱动的 dIm-Ag-dIm 和 dImTP-Cr-dIm 碱基对的形成。似乎是空间因素而不是咪唑核苷碱基的碱性决定了这种金属碱基对的酶促形成。我们还证明了在引物延伸反应和 PCR 条件下，通过酶促 DNA 合成，其他在人工金属碱基构建中很少考虑的金属阳离子的兼容性。这些发现为设计用于开发金属碱基对的核苷酸类似物开辟了新的方向。
