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Updated: Feb 26, 2026
Isolation of Translating Ribosomes Containing Peptidyl-tRNAs for Functional and Structural Analyses
Published on: February 25, 2011
An antimicrobial peptide that inhibits translation by trapping release factors on the ribosome
Tanja Florin1, Cristina Maracci2, Michael Graf3
1Center for Biomolecular Sciences, University of Illinois at Chicago, Chicago, Illinois, USA.
Abstract:
Many antibiotics stop bacterial growth by inhibiting different steps of protein synthesis. However, no specific inhibitors of translation termination are known. Proline-rich antimicrobial peptides, a component of the antibacterial defense system of multicellular organisms, interfere with bacterial growth by inhibiting translation. Here we show that Api137, a derivative of the insect-produced antimicrobial peptide apidaecin, arrests terminating ribosomes using a unique mechanism of action. Api137 binds to the Escherichia coli ribosome and traps release factor (RF) RF1 or RF2 subsequent to the release of the nascent polypeptide chain. A high-resolution cryo-EM structure of the ribosome complexed with RF1 and Api137 reveals the molecular interactions that lead to RF trapping. Api137-mediated depletion of the cellular pool of free release factors causes the majority of ribosomes to stall at stop codons before polypeptide release, thereby resulting in a global shutdown of translation termination.
Insights
Api137, a novel antimicrobial peptide, halts bacterial protein synthesis by uniquely trapping essential release factors (RFs) on ribosomes. This discovery offers a new strategy for developing antibiotics targeting translation termination.
Area of Science:
- Microbiology
- Molecular Biology
- Structural Biology
Background:
- Antibiotics commonly inhibit bacterial protein synthesis.
- Specific inhibitors of translation termination are currently unknown.
- Antimicrobial peptides can interfere with bacterial translation.
Purpose of the Study:
- To identify and characterize inhibitors of translation termination.
- To elucidate the mechanism of action of Api137, an apidaecin derivative.
- To investigate the structural basis of Api137-ribosome interaction.
Main Methods:
- Bacterial growth inhibition assays.
- Cryo-electron microscopy (cryo-EM) to determine high-resolution structures.
- Biochemical assays to study release factor (RF) interactions.
Main Results:
- Api137 arrests terminating ribosomes by trapping RF1 or RF2.
- Cryo-EM revealed molecular interactions responsible for RF trapping.
- Api137 causes ribosome stalling at stop codons, leading to translation termination shutdown.
Conclusions:
- Api137 represents a novel class of translation termination inhibitors.
- The unique mechanism of Api137 offers a new avenue for antibiotic development.
- Targeting translation termination is a viable strategy against bacterial infections.
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