Twister is a small ribozyme present in almost all kingdoms of life that rapidly self-cleaves in variety of divalent metal ions. We used activity assays, bulk FRET and single-molecule FRET (smFRET) to understand how different metal ions promote folding and self-cleavage of the Oryza sativa twister ribozyme. Although most ribozymes require additional Mg²⁺ for catalysis, twister inverts this expectation, requiring 20–30 times less Mg²⁺ to self-cleave than to fold. Transition metals such as Co²⁺, Ni²⁺ and Zn²⁺ activate twister more efficiently than Mg²⁺ ions. Although twister is fully active in ≤ 0.5 mM MgCl₂, smFRET experiments showed that the ribozyme visits the folded state infrequently under these conditions. Comparison of folding and self-cleavage rates indicates that most folding events lead to catalysis, which correlates with metal bond strength. Thus, the robust activity of twister reports on transient metal ion binding under physiological conditions.

中文翻译：

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金属诱导扭转分子核酶的瞬时折叠和活化

Twister是存在于几乎所有生命王国中的一种小型核酶，可迅速自我裂解成各种二价金属离子。我们使用活性分析，本体FRET和单分子FRET（smFRET）来了解不同的金属离子如何促进水稻稻纵卷线虫核酶的折叠和自我裂解。尽管大多数核酶需要额外的Mg ²⁺来催化，但扭转者却扭转了这种期望，自我裂解所需Mg ²⁺比折叠所需Mg ²⁺少20-30倍。过渡金属（例如Co 2 ⁺，Ni ²⁺和Zn ^2+）比Mg ²⁺离子更有效地激活扭曲物。尽管加捻器在≤0.5 mM MgCl _2中完全起作用，smFRET实验表明，在这些条件下，核酶很少进入折叠状态。折叠速率和自切割速率的比较表明，大多数折叠事件导致催化作用，这与金属结合强度有关。因此，在生理条件下，扭转器的强健活性报道了瞬时金属离子结合。