Abstract
Riboswitches are RNA sequences that regulate gene expression by undergoing structural changes upon the specific binding of cellular metabolites. Crystal structures of purine-sensing riboswitches have revealed an intricate network of interactions surrounding the ligand in the bound complex. The mechanistic details about how the aptamer folding pathway is involved in the formation of the metabolite binding site have been previously shown to be highly important for the riboswitch regulatory activity. Here, a combination of single-molecule FRET and SHAPE assays have been used to characterize the folding pathway of the adenine riboswitch from Vibrio vulnificus. Experimental evidences suggest a folding process characterized by the presence of a structural intermediate involved in ligand recognition. This intermediate state acts as an open conformation to ensure ligand accessibility to the aptamer and folds into a structure nearly identical to the ligand-bound complex through a series of structural changes. This study demonstrates that the add riboswitch relies on the folding of a structural intermediate that pre-organizes the aptamer global structure and the ligand binding site to allow efficient metabolite sensing and riboswitch genetic regulation.
Highlights
Gene expression requires the assistance of numerous cofactors to provide the specificity and timing of regulation, which are important to ensure cellular homeostasis
A striking example about the importance of RNA folding in gene expression was obtained with the discovery of riboswitches that are genetic regulatory elements found in the 5 untranslated region (5 UTR) of bacterial messenger RNA [2,3,4]
The ability of singlemolecule Forster resonance energy transfer (smFRET) to resolve transient RNA structures and to determine intramolecular distances was used to characterize the structural features of intermediate state and its role in metabolite recognition
Summary
Gene expression requires the assistance of numerous cofactors to provide the specificity and timing of regulation, which are important to ensure cellular homeostasis. Accumulating evidence suggests that RNA folding is central for gene regulation, by providing specific protein binding sites and important architectural domains [1]. Riboswitches are involved in the control of gene expression by modulating their structure upon the binding of specific cellular metabolites [2]. The formation of the aptamer-ligand complex influences the structure of the riboswitch expression platform that is directly implicated in the regulation of gene expression, either by modulating mRNA levels or the initiation of translation [2,4]. Riboswitches have been involved to modulate splicing [6,7] and to regulate gene expression in a trans-acting manner [8]
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
