The Salk Institute, 10010 North Torrey Pines Road, La Jolla, California 92037, United States.
J Am Chem Soc. 2021 Nov 17;143(45):19160-19166. doi: 10.1021/jacs.1c09233. Epub 2021 Nov 3.
Informational macromolecules in biology are composed of subunits of a single handedness, d-nucleotides in nucleic acids and l-amino acids in proteins. Although this chiral uniformity may be expedient, it is not a chemical necessity, as demonstrated by the recent example of an RNA enzyme that catalyzes the RNA-templated polymerization of RNA molecules of the opposite handedness. This reaction, when carried out iteratively, can provide the basis for exponential amplification of RNA molecules and the information they contain. By carrying out thermal cycling, analogous to the polymerase chain reaction, and supplying oligonucleotide building blocks that comprise both the functional strand of RNA and its complement, cross-chiral exponential amplification was achieved. This process was used to amplify the l-RNA form of the hammerhead ribozyme, catalyzed by the d-RNA form of the polymerase. The resulting l-hammerhead exhibits the expected activity in cleaving a corresponding l-RNA substrate. Exponential amplification was also carried out within individual droplets of a water-in-oil emulsion. The ability to amplify enantio-RNAs, both in bulk solution and within compartments, provides a means to evolve cross-chiral RNA polymerases based on the function of the RNAs they produce.
生物中的信息大分子由单一手性的亚单位组成，核酸中的 d-核苷酸和蛋白质中的 l-氨基酸。尽管这种手性均一性可能是方便的，但它不是化学上的必然，最近的一个 RNA 酶的例子证明了这一点，该酶催化相反手性的 RNA 分子的 RNA 模板聚合。这种反应，如果进行迭代，可以为 RNA 分子及其所包含的信息的指数扩增提供基础。通过进行类似于聚合酶链式反应的热循环，并提供包含 RNA 的功能链及其互补链的寡核苷酸构建块，实现了交叉手性指数扩增。该过程用于扩增由 d-RNA 形式的聚合酶催化的 l-RNA 形式的 hammerhead 核酶。所得的 l-hammerhead 在切割相应的 l-RNA 底物时表现出预期的活性。指数扩增也在油包水乳液的单个液滴内进行。在大规模溶液和隔室中扩增对映体 RNA 的能力为基于它们产生的 RNA 的功能来进化交叉手性 RNA 聚合酶提供了一种手段。
