mRNA structural dynamics shape Argonaute-target interactions

bioRxiv preprint first posted online Oct. 30, 2019; doi: http://dx.doi.org/10.1101/822452. The copyright holder for this preprint (which was not peer-reviewed) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. All rights reserved. No reuse allowed without permission.
Authors
Suzan Ruijtenberg, Stijn Sonneveld, Tao Ju Cui, Ive Logister, Dion de Steenwinkel, Yao Xiao, Ian J. MacRae, Chirlmin Joo, Marvin E. Tanenbaum
11-06-2019 HSW 1057
12:00pm
PST
Categories
RNPs Biogenesis, Structure & Function
Speaker
Hannah N Gruner
Abstract

Small RNAs (such as miRNAs, siRNAs and piRNAs) regulate protein expression in a wide variety of biological processes and play an important role in cellular function, development and disease. Association of small RNAs with Argonaute (AGO) family proteins guide AGO to target RNAs, generally resulting in target silencing through transcriptional silencing, translational repression or mRNA degradation. Here we develop a live-cell single-molecule imaging assay to simultaneously visualize translation of individual mRNA molecules and their silencing by human AGO2-siRNA complexes. We find that siRNA target sites are commonly masked in vivo by RNA secondary structures, which inhibit AGO2-target interactions. Translating ribosomes unmask AGO2 binding sites, stimulating AGO2-target interactions and promoting mRNA degradation. Using a combination of mathematical modeling and experiments, we find that mRNA structures are highly heterogeneous and continuously refolding. We show that structural dynamics of mRNAs shape AGO2-target recognition, which may be a common feature controlling mRNA-protein interactions.