Basu S, Rambo R P, Strauss-Soukup J, Cate J H, Ferré-D'Amaré A R, Strobel S A, Doudna J A
Center for Chemical Biology, Yale University, New Haven, Connecticut 06520, USA.
Nat Struct Biol. 1998 Nov;5(11):986-92. doi: 10.1038/2960.
Metal ions are essential for the folding and activity of large catalytic RNAs. While divalent metal ions have been directly implicated in RNA tertiary structure formation, the role of monovalent ions has been largely unexplored. Here we report the first specific monovalent metal ion binding site within a catalytic RNA. As seen crystallographically, a potassium ion is coordinated immediately below AA platforms of the Tetrahymena ribozyme P4-P6 domain, including that within the tetraloop receptor. Interference and kinetic experiments demonstrate that potassium ion binding within the tetraloop receptor stabilizes the folding of the P4-P6 domain and enhances the activity of the Azoarcus group I intron. Since a monovalent ion binding site is integral to the tetraloop receptor, a tertiary structural motif that occurs frequently in RNA, monovalent metal ions are likely to participate in the folding and activity of a wide diversity of RNAs.
金属离子对于大型催化RNA的折叠和活性至关重要。虽然二价金属离子已直接参与RNA三级结构的形成，但一价离子的作用在很大程度上尚未得到探索。在此，我们报道了催化RNA中首个特定的一价金属离子结合位点。从晶体学观察来看，一个钾离子紧邻嗜热四膜虫核酶P4-P6结构域的AA平台下方配位，包括四环受体中的AA平台。干扰和动力学实验表明，四环受体内的钾离子结合稳定了P4-P6结构域的折叠，并增强了偶氮螺菌属I组内含子的活性。由于一价离子结合位点是RNA中频繁出现的三级结构基序——四环受体的组成部分，一价金属离子很可能参与了多种RNA的折叠和活性。
