Related Experiment Video
Updated: May 4, 2026
Single Molecule Fluorescence Energy Transfer Study of Ribosome Protein Synthesis
Published on: July 6, 2021
Structured mRNA induces the ribosome into a hyper-rotated state
Peiwu Qin1, Dongmei Yu, Xiaobing Zuo
1Department of Biochemistry, University of Missouri, Columbia, MO, USA.
Abstract:
During protein synthesis, mRNA and tRNA are moved through the ribosome by the process of translocation. The small diameter of the mRNA entrance tunnel only permits unstructured mRNA to pass through. However, there are structured elements within mRNA that present a barrier for translocation that must be unwound. The ribosome has been shown to unwind RNA in the absence of additional factors, but the mechanism remains unclear. Here, we show using single molecule Förster resonance energy transfer and small angle X-ray scattering experiments a new global conformational state of the ribosome. In the presence of the frameshift inducing dnaX hairpin, the ribosomal subunits are driven into a hyper-rotated state and the L1 stalk is predominantly in an open conformation. This previously unobserved conformational state provides structural insight into the helicase activity of the ribosome and may have important implications for understanding the mechanism of reading frame maintenance.
Insights
The ribosome unwinds mRNA structures during translocation, revealing a new hyper-rotated state. This finding offers structural insights into the ribosome's helicase activity and reading frame maintenance.
Area of Science:
- Molecular Biology
- Structural Biology
- Biophysics
Background:
- Protein synthesis involves ribosome translocation of mRNA and tRNA.
- mRNA secondary structures can impede translocation, requiring unwinding.
- The ribosome's intrinsic RNA unwinding mechanism is not fully understood.
Purpose of the Study:
- To elucidate the structural mechanism of ribosome-mediated RNA unwinding.
- To investigate the ribosome's conformational changes during translocation of structured mRNA.
- To understand the role of these changes in reading frame maintenance.
Main Methods:
- Single molecule Förster resonance energy transfer (smFRET).
- Small angle X-ray scattering (SAXS).
- Utilized the frameshift-inducing dnaX hairpin as a model RNA structure.
Main Results:
- Identified a novel global conformational state of the ribosome.
- Observed ribosome subunit hyper-rotation and L1 stalk opening in the presence of the dnaX hairpin.
- Demonstrated ribosome-induced unwinding of structured mRNA.
Conclusions:
- The ribosome adopts a hyper-rotated, L1 stalk-open state to facilitate RNA unwinding.
- This conformational state provides structural basis for the ribosome's helicase activity.
- Findings have implications for understanding mRNA translocation and reading frame maintenance.
Related Concept Videos
02:33Initiation of Translation
First, the initiator tRNA must be selected from the pool of elongator tRNAs by eukaryotic initiation factor 2 (eIF2). The initiator tRNA (Met-tRNAi) has conserved sequence elements including modified bases at...
02:33Initiation of Translation
02:53Ribosomal RNA Synthesis
Ribosome biogenesis begins with the synthesis of 5S and 45S pre-rRNAs by distinct RNA polymerases. The primary transcripts are extensively processed and modified before they are bound and folded by ribosomal proteins and assembly factors,...
02:53Ribosomal RNA Synthesis
01:29Translational Regulation
01:34Directing Proteins to the Rough Endoplasmic Reticulum