CAREER:RNA conformational dynamics in the regulation of microRNA biogenesis

University Of North Carolina At Chapel Hill, Chapel Hill NC

Investigators

Abstract

RNA is one of the three major biological macromolecules that are essential for all known forms of life (along with DNA and proteins). While for many years RNA was believed to have only three major roles in the cell, it is now known that the roles adopted by RNA are much broader and interesting. MicroRNAs are a class of evolutionarily conserved, small noncoding RNAs. They regulate more than 60% of all protein genes, and serve as critical regulators in all biological processes. Due to their central role in gene regulation, microRNAs themselves are tightly regulated. This project will investigate how conformational dynamics in two distinct microRNAs control recognition of specific protein cofactors to regulate their processing pathways. Results of this project will provide important mechanistic insights into the regulation of these essential gene regulators. This project will expand the current knowledge of RNA-protein interactions and deepen the understanding of the functional roles of RNA conformational dynamics in biology. Research and education will be integrated in this project to support scientific training and education of undergraduate and graduate students as well as underrepresented high-school students in STEM principles. An on-campus program will be developed for high-school students featuring an annual scientific forum and summer research internships. Outreach activities to local high schools will be carried out to develop innovative STEM teaching approaches. MicroRNA biogenesis is a dynamic and regulated process. During the canonical biogenesis pathway, the apical-loop regions of primary and precursor microRNAs play critical regulatory roles. However, these RNA elements are highly flexible and have evaded high-resolution structural study by conventional structural biology techniques. Recent developments in nucleic acid NMR spectroscopy, including those from the PI, have opened new avenues to characterize complex conformational dynamics and transitions in highly flexible RNAs. This project will further develop and apply these NMR methods, together with biochemical and computational approaches, to understand the mechanism by which microRNA biogenesis is regulated via specific RNA-protein interactions. Using microRNA-1 and microRNA-21 as model systems, this project will visualize RNA conformational dynamics in microRNA precursors and elucidate the structural and molecular basis for the regulatory roles of protein cofactors in microRNA biogenesis. Results will be used to evaluate the central hypothesis of this project that the apical-loop regions of primary and precursor microRNAs dynamically sample distinct conformations for protein recognition and that these dynamics may be tuned to affect protein-RNA interactions to direct biogenesis pathways.