Department of Chemistry and the Center for Cell and Genome Science, University of Utah, Salt Lake City, UT 84112, USA.
Department of Chemistry, Emory University, Atlanta, GA 30322, USA.
Nucleic Acids Res. 2018 Sep 19;46(16):8057-8068. doi: 10.1093/nar/gky667.
Despite advances in XNA evolution, the binding capabilities of artificial genetic polymers are currently limited to protein targets. Here, we describe the expansion of in vitro evolution techniques to enable selection of threose nucleic acid (TNA) aptamers to ochratoxin A (OTA). This research establishes the first example of an XNA aptamer of any kind to be evolved having affinity to a small-molecule target. Selection experiments against OTA yielded aptamers having affinities in the mid nanomolar range; with the best binders possessing KD values comparable to or better than those of the best previously reported DNA aptamer to OTA. Importantly, the TNA can be incubated in 50% human blood serum for seven days and retain binding to OTA with only a minor change in affinity, while the DNA aptamer is completely degraded and loses all capacity to bind the target. This not only establishes the remarkable biostability of the TNA aptamer, but also its high level of selectivity, as it is capable of binding OTA in a large background of competing biomolecules. Together, this research demonstrates that refining methods for in vitro evolution of XNA can enable the selection of aptamers to a broad range of increasingly challenging target molecules.
尽管 XNA 进化取得了进展，但人工遗传聚合物的结合能力目前仅限于蛋白质靶标。在这里，我们描述了体外进化技术的扩展，以实现对赭曲霉毒素 A（OTA）的 threose 核酸（TNA）适体的选择。这项研究确立了第一个具有亲和力的小分子靶标的任何类型的 XNA 适体的进化的例子。针对 OTA 的选择实验产生了具有中纳摩尔亲和力的适体；最好的结合物具有 KD 值与最好的先前报道的 OTA 的 DNA 适体相当或更好。重要的是，TNA 可以在 50%的人血清中孵育七天，并且仅在亲和力略有变化的情况下保留与 OTA 的结合，而 DNA 适体完全降解并丧失与靶标结合的所有能力。这不仅确立了 TNA 适体的卓越的生物稳定性，而且还确立了其高水平的选择性，因为它能够在大量竞争生物分子的背景下结合 OTA。总之，这项研究表明，改进 XNA 体外进化的方法可以选择针对广泛的、越来越具有挑战性的靶分子的适体。
