Jose A M, Soukup G A, Breaker R R
Department of Molecular, Cellular and Developmental Biology, KBT 452, Yale University, PO Box 208103, New Haven, CT 06520-8103, USA.
Nucleic Acids Res. 2001 Apr 1;29(7):1631-7. doi: 10.1093/nar/29.7.1631.
An allosteric ribozyme that requires two different effectors to induce catalysis was created using modular rational design. This ribozyme construct comprises five conjoined RNA modules that operate in concert as an obligate FMN- and theophylline-dependent molecular switch. When both effectors are present, this 'binary' RNA switch self-cleaves with a rate enhancement of approximately 300-fold over the rate observed in the absence of effectors. Kinetic and structural studies implicate a switching mechanism wherein FMN binding induces formation of the active ribozyme conformation. However, the binding site for FMN is rendered inactive unless theophylline first binds to its corresponding site and reorganizes the RNA structure. This example of cooperative binding between allosteric effectors reveals a level of structural and functional complexity for RNA that is similar to that observed with allosteric proteins.
通过模块化合理设计构建了一种需要两种不同效应物来诱导催化作用的变构核酶。这种核酶构建体由五个相连的RNA模块组成，它们协同作为一个严格依赖黄素单核苷酸（FMN）和茶碱的分子开关发挥作用。当两种效应物都存在时，这种“二元”RNA开关会自我切割，其速率比在没有效应物时观察到的速率提高约300倍。动力学和结构研究表明存在一种开关机制，其中FMN结合诱导活性核酶构象的形成。然而，除非茶碱首先结合到其相应位点并重组RNA结构，否则FMN的结合位点是无活性的。变构效应物之间这种协同结合的例子揭示了RNA在结构和功能上的复杂程度，这与变构蛋白所观察到的相似。
