Abstract：
The RNA World theory encompasses the hypothesis that sophisticated ribozymes and riboswitches were the primary drivers of metabolic processes in ancient organisms. Several types of catalytic RNAs and many classes of ligand-sensing RNA switches still exist in modern cells. Curiously, allosteric ribozymes formed by the merger of RNA enzyme and RNA switch components are largely absent in today\'s biological systems. This is true despite the striking abundances of various classes of both self-cleaving ribozymes and riboswitch aptamers. Here we present the known types of ligand-controlled ribozymes and riboswitches and discuss the possible reasons why fused ribozyme-aptamer constructs have been disfavored through evolution.
摘要：
RNA世界理论涵盖了复杂的核酶和核糖开关是古代生物代谢过程的主要驱动因素的假设。现代细胞中仍然存在几种类型的催化RNA和许多类型的配体感应RNA开关。奇怪的是,在今天的生物系统中，由RNA酶和RNA开关成分合并形成的变构核酶基本上不存在。尽管各种类型的自切割核酶和核糖开关适体具有惊人的丰度,但这是真的。在这里，我们介绍了已知类型的配体控制的核酶和核糖开关，并讨论了融合的核酶-适体构建体在进化过程中不受欢迎的可能原因。
