Cancer Research UK Nucleic Acid Structure Research Group, MSI/WTB Complex, The University of Dundee, Dundee, UK.
Wiley Interdiscip Rev RNA. 2012 Nov-Dec;3(6):797-805. doi: 10.1002/wrna.1136. Epub 2012 Sep 13.
The kink turn (k-turn) is a widespread structural motif that introduces a tight kink into the axis of double-stranded RNA, with an included angle ∼60°. A standard k-turn comprises a three-nucleotide bulge followed on the 3' side by a G•A pair, an A•G pair, and usually further non-Watson-Crick pairs. The kinked conformation may be stabilized by three processes. These are the addition of metal ions, the binding of proteins such as the L7Ae family, and by the formation of tertiary interactions. The structure is characterized by specific A-minor interactions with the adenine nucleobases of the G•A pairs, and some very well-conserved hydrogen bonds involving 2'-hydroxyl groups. We can identify two classes of k-turns, that differ in the manner of the hydrogen bonding at the adenine of the bulge-distal G•A pair.
发夹转弯（k-turn）是一种广泛存在的结构基序，它在双链 RNA 的轴线上引入一个紧密的发夹，夹角约为 60°。一个标准的发夹转弯由三个核苷酸的凸起组成，在 3' 端后面是一个 G•A 对、一个 A•G 对，通常还有进一步的非 Watson-Crick 碱基对。发夹的构象可以通过三种过程来稳定。这些过程是添加金属离子、结合 L7Ae 家族等蛋白质，以及形成三级相互作用。该结构的特征是与 G•A 对的腺嘌呤核苷酸碱基形成特定的 A 型小沟相互作用，以及一些非常保守的涉及 2'-羟基的氢键。我们可以识别两种类型的发夹转弯，它们在凸起远端 G•A 对的腺嘌呤氢键的方式上有所不同。
