AI Article Synopsis
- The study focuses on the RelA/SpoT-homolog proteins in bacteria, which play a critical role in the stress response and contribute to antibiotic resistance.
- Researchers used cryo-electron microscopy (cryo-EM) to visualize the structure of E. coli RelA bound to the ribosome in different states, particularly when tRNA is present.
- The findings reveal multiple conformations of the ribosome and tRNA interactions that highlight the complexities of tRNA decoding and its regulatory mechanisms during stress responses.
Article Abstract
Stringent response is a conserved bacterial stress response underlying virulence and antibiotic resistance. RelA/SpoT-homolog proteins synthesize transcriptional modulators (p)ppGpp, allowing bacteria to adapt to stress. RelA is activated during amino-acid starvation, when cognate deacyl-tRNA binds to the ribosomal A (aminoacyl-tRNA) site. We report four cryo-EM structures of E. coli RelA bound to the 70S ribosome, in the absence and presence of deacyl-tRNA accommodating in the 30S A site. The boomerang-shaped RelA with a wingspan of more than 100 Å wraps around the A/R (30S A-site/RelA-bound) tRNA. The CCA end of the A/R tRNA pins the central TGS domain against the 30S subunit, presenting the (p)ppGpp-synthetase domain near the 30S spur. The ribosome and A/R tRNA are captured in three conformations, revealing hitherto elusive states of tRNA engagement with the ribosomal decoding center. Decoding-center rearrangements are coupled with the step-wise 30S-subunit 'closure', providing insights into the dynamics of high-fidelity tRNA decoding.
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Source |
|---|---|
| http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4974054 | PMC |
| http://dx.doi.org/10.7554/eLife.17029 | DOI Listing |
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