Seelig B, Jäschke A
Institut für Biochemie der FU Berlin Thielallee 63 14195 Berlin Germany.
Chem Biol. 1999 Mar;6(3):167-76. doi: 10.1016/S1074-5521(99)89008-5.
The 'RNA world' hypothesis requires that RNA be able to catalyze a wide variety of chemical reactions. In vitro selection from combinatorial RNA libraries has been used to identify several catalytic activities, most of which have resulted in a self-modification of RNA at one of its constituents. The formation of carbon-carbon bonds is considered an essential prerequisite for a complex metabolism based on RNA.
We describe the selection and characterization of new ribozymes that catalyze carbon-carbon bond formation by Diels-Alder reaction of a biotinylated maleimide with an RNA-tethered anthracene. Secondary structure analysis identified a 49-nucleotide RNA motif that accelerates the reaction about 20,000-fold. The motif has only 11 conserved nucleotides that are present in most of the selected sequences. The ribozyme motif is remarkably adaptable with respect to cofactor and metal-ion requirements. The motif was also re-engineered to give a 38-mer RNA that can act as a 'true' catalyst on short external substrate oligonucleotide-anthracene conjugates.
We have identified a small, highly abundant RNA motif that can solve the complex task of forming two carbon-carbon bonds between two reactants in trans, a catalytic capacity useful for creating prebiotically relevant molecules. This is the smallest and fastest RNA catalyst for carbon-carbon bond formation reported to date.
“RNA世界”假说要求RNA能够催化多种化学反应。从组合RNA文库中进行体外筛选已用于鉴定多种催化活性，其中大多数导致RNA在其一种成分上发生自我修饰。碳-碳键的形成被认为是基于RNA的复杂代谢的必要前提。
我们描述了通过生物素化马来酰亚胺与RNA连接的蒽的狄尔斯-阿尔德反应催化碳-碳键形成的新核酶的筛选和表征。二级结构分析确定了一个49个核苷酸的RNA基序，该基序使反应加速约20000倍。该基序在大多数选定序列中仅具有11个保守核苷酸。核酶基序在辅因子和金属离子需求方面具有显著的适应性。该基序还经过重新设计，得到一种38聚体RNA，它可以对短的外部底物寡核苷酸-蒽共轭物起“真正”催化剂的作用。
我们鉴定出一个小的、高度丰富的RNA基序，它可以解决在反式中两个反应物之间形成两个碳-碳键的复杂任务，这种催化能力有助于生成与益生元相关的分子。这是迄今为止报道的用于碳-碳键形成的最小且最快的RNA催化剂。
