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Updated: May 9, 2026
08:07
Single Molecule Fluorescence Energy Transfer Study of Ribosome Protein Synthesis
Published on: July 6, 2021
The ribosome triggers the stringent response by RelA via a highly distorted tRNA
Xabier Agirrezabala1, Israel S Fernández, Ann C Kelley
1CIC bioGUNE, Structural Biology Unit, Bldg 800, Biscay Technology Park, Derio 48160, Basque Country, Spain.
EMBO Reports
|July 24, 2013
Summary
The stringent response regulator RelA binds to ribosomes during nutrient starvation. Cryo-EM reveals RelA distorts tRNA, altering its position for (p)ppGpp alarmone synthesis.
Area of Science:
- Bacterial physiology
- Molecular biology
- Structural biology
Background:
- The bacterial stringent response regulates gene expression during nutrient starvation.
- This response is triggered by the RelA protein, which synthesizes the alarmone (p)ppGpp.
- RelA activation occurs when it senses deacylated tRNA in the ribosome, indicating amino-acid starvation.
Purpose of the Study:
- To elucidate the structural mechanism of RelA activation on the ribosome.
- To visualize the interaction between RelA, ribosome, and deacylated tRNA.
Main Methods:
- Cryo-electron microscopy (cryo-EM) was used to determine the structure.
- The study focused on RelA bound to ribosomes containing deacylated tRNA in the A-site.
Main Results:
- RelA binds to ribosomes with deacylated tRNA in the A-site.
- RelA stabilizes a significantly distorted conformation of the tRNA.
- The tRNA acceptor arm interacts with RelA, moving away from the peptidyl transferase center.
Conclusions:
- This structural rearrangement is key to RelA's activation during starvation.
- The findings provide atomic-level insight into stringent response initiation.
- Understanding this mechanism can inform strategies targeting bacterial stress responses.
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