Evolutionary, structural and functional explorations of non-coding RNA and protein genetic robustness

Abstract

The reactions of functional molecules like RNAs and proteins to mutation affect both host cell viability and biomolecular evolution. These molecules are considered robust if function is maintained alongside the mutation. RNAs and proteins have different structural and functional characteristics that affect their robustness, and to date, comparisons between them have been theoretical. In this work, we tested the relative mutational robustness of RNA and protein pairs using three approaches: evolutionary, structural, and functional. We compared the nucleotide diversities of functional RNAs with those of matched proteins. Across different levels of conservation, there were no differences in nucleotide-level variations between the biomolecules. We then directly tested the robustness of the RNA and protein pairs with in vitro and in silico mutagenesis of their respective genes. The in silico experiments showed that RNAs and proteins reacted similarly to point mutations and insertions or deletions. In vitro, mutated fluorescent RNAs retained greater levels of function than the proteins, but this may be because of differences in the robustness of the specific individual molecules rather than being indicative of a larger trend. In this first experimental comparison of proteins and RNAs, we found no consistent quantitative differences in mutational robustness. Future work on potential qualitative differences and other forms of robustness will give further insight into the evolution and functionality of biomolecules.