Exploring the 5'-GUAC- sequence as an important RNA-motif

Project Summary: RNA motifs can be assigned based on their sequence and/or structure, and are central to many biological processes. Examples of structural motifs include hairpins, internal loops, or bulges, which are known to serve several functions; similarly, examples of sequence motifs, can be those where a particular sequence is repeated, or conserved across different organisms/species, and also play important roles in biology. The Resendiz lab recently found that the palindromic RNA sequence 5'-GUAC- hybridizes with its complement, with an inherited disorder, when present in various duplex contexts, i.e., within GUAC repeats, double stranded chains of varying size, hairpin stem and loops, and internal loops. Preliminary data suggests that this `disorder' can be assigned to regions adopting a Z-type conformation. Importantly, this motif is found in various types of RNA that include viral RNA, micro-RNA, and transfer-RNA; thus the outcomes of this study will have broader implications in different biological systems. This work will establish the nature of the disorder found in the 5'-GUAC- RNA motif and explore its potential relevance in various biological constructs. The proposed work represents the first study that considers this sequence, as a motif, and that will establish the nature of the observed structural changes; which will be of potential importance, broadly. Structural aspects will be established using a combination of standard biophysical techniques that include circular dichroism, X-ray crystallography, NMR, electrophoresis, calorimetry, and organic synthesis of models that will probe various conformational spaces. The information will then be used to understand its impact on biologically relevant RNA. To this end, the structural impact of the 5'-GUAC sequence will be explored in two models for viral RNA [Human Rhino virus (HRV) and Severe Acute Respiratory Syndrome Coronavirus isotype-2 (SARS-CoV-2); and one for micro-RNA (miR-486). Understanding the elements that are necessary to exhibit the observed behavior, will allow researchers to treat/use this motif as an important structural element, within various constructs of RNA. The PI's group hypothesizes that this motif can become a potential druggable target, due to its unique structure and likelihood to interact with metabolites in a distinct manner; as well as a sequence with unique capabilities to interact with other biopolymers, i.e., RNA, DNA, or proteins. The proposed research has the potential to be of high impact, and of interest to various fields.