GNRA/receptor interacting modules: Versatile modular units for natural and artificial RNA architectures

Interactions between GNRA tetraloops and their receptors are found frequently as modular units in various types of naturally occurring structured RNAs. Due to their functional importance, GNRA/receptor interactions have been studied extensively with regard to their 3D structures and biochemical and biophysical properties. Artificial non-natural GNRA/receptor modules have also been generated not only to obtain a better understanding of this class of motifs in natural RNA structures but also for application of these modular units to the design and construction of artificial RNA structures that can be used as platforms to generate functional RNAs applicable for nanobiotechnology. In this review, we present a survey of structures, functions, and analyses as well as artificial generation and application of GNRA/receptor interacting modules.