Science-美研制出可自我复制的人造DNA结构
Science：美研制出可自我复制的人造DNA结构
2011/10/21 11:05:10
据每日科学网站10月18日（北京时间）报道，纽约大学科学家研发出一种能自我复制的人造DNA（脱氧核糖核酸）结构，有望为新型材料的制造奠定基础。相关论文发表在最新一期的《自然》杂志上。
自然界中，自我复制在生物体中普遍存在，但人造结构的自我复制却很难实现。此次研究是迈向自主复制任意类型“种子”结构过程的第一步。这些“种子” 由DNA模片制成，可像字母般组合拼出特定“单词”。复制过程保留了模片序列及“种子”形状，从而提供了生成下一代结构所需的信息。
此次研究的突破在于成功复制了包含复杂信息的DNA系统。研究人员首先从人造DNA模片开始，这是DNA的细小排列。DNA的腺嘌呤（A）和胸腺嘧啶（T）、鸟嘌呤（G）和胞嘧啶(C)互相结对形成人们熟悉的双螺旋结构。研究人员制成了含有3个DNA双螺旋结构的弯曲三螺旋分子（BTX）。每个 BTX分子由10个DNA索烃构成，与DNA不同的是，BTX的编码不局限于4个字母，它能够包含108个不同字母和模片，借助4个DNA单索的互补形成一对，或在每个模片上形成“黏性末端”，直至构成最终的6个螺旋束（six-helix bundle）。
为实现BTX自我复制模片阵列，需要“种子”结构促进多代相同阵列的形成。BTX“种子”被放置于化学溶液中，由7个模片组成，模片可以互补形成子代BTX阵列，该阵列随后会在溶液加热至40℃时与“种子”分离，并循环重复这一过程，形成第三代阵列，从而实现材料的自我复制及“种子”的信息复制。值得注意的是，这个过程与发生在细胞内部的复制过程不同，因为执行中无需添加酶等生物成分，即使是DNA模片也由人工合成。
研究的共同作者、该校化学系的纳德里安·西曼指出：“虽然我们的复制方法需要多种化学物质和加热过程，但已经证明不仅可以复制DNA或RNA等细胞分子，还可以复制众多特别的结构，实现多个化学形态不同、功能特性相异的结构的复制。”
Self-replication of information-bearing nanoscale patterns
Tong Wang; Ruojie Sha; Rémi Dreyfus; Mirjam E. Leunissen; Corinna Maass; David J. Pine; Paul M. Chaikin; Nadrian C. Seeman
DNA molecules provide what is probably the most iconic example of self-replication—the ability of a system to replicate, or make copies of, itself. In living cells the process is mediated by enzymes and occurs autonomously, with the number of replicas increasing exponentially over time without the need for external manipulation. Self-replication has also been implemented with synthetic systems, including RNA enzymes designed to undergo self-sustained exponential amplification1, 2, 3, 4, 5. An exciting next step would be to use self-replication in materials fabrication, which requires robust and general systems capable of copying and amplifying functional materials or structures. Here we report a first development in this direction, using DNA tile motifs that can recognize and bind complementary tiles in a pre-programmed fashion. We first design tile motifs so they form a seven-tile seed sequence; then use the seeds to instruct the formation of a first generation of complementary seven-tile daughter sequences; and finally use the daughters to instruct the formation of seven-tile granddaughter sequences that are identical to the initial seed sequences. Considering that DNA is a functional material that can organize itself and other molecules into useful structures6, 7, 8, 9, 10, 11, 12, 13, our findings raise the tantalizing prospect that we may one day be able to realize self-replicating materials with various patterns or useful functions.