# Advancing ribosome-targeting antibacterial peptides with a unique mechanism of action

> **NIH NIH R56** · UNIVERSITY OF ILLINOIS AT CHICAGO · 2021 · $730,027

## Abstract

Project Summary
 Apidaecin (Api), an antimicrobial peptide produced by honeybees, has a unique mechanism of action. Our previous
studies showed that after entering the cell of Gram-negative bacteria through the SbmA transporter, Api binds in the nascent
peptide exit tunnel of the bacterial ribosome, traps the release factors and arrests translation at stop codons. As such, Api
represents the first-ever specific inhibitor of translation termination. Our subsequent whole-genome studies have shown
that arresting terminating ribosomes triggers a number of downstream events, including ribosome queuing and readthrough
of stop codons, that accentuate Api's primary inhibitory action. The idiosyncratic mode of binding to the target, the unique
mechanism of action, and the triggering of downstream effects harmful for the bacterial cell, make Api an attractive model
for developing novel antibiotics with improved properties.
 In the current proposal we will use the combined effort of three laboratories with expertise in ribosomal antibiotics,
peptide chemistry and structural analysis to advance the fundamental understanding of action of Api-like inhibitors and
identify Api derivatives with superior on-target activity and expanded spectrum of antibacterial action. We will achieve these
goals by generating and testing arrays of Api variants directly in the bacterial cell by the controlled expression of gene
libraries, synthesizing peptides with specific chemical modifications, and determining X-ray crystal structures of ribosome-
Api complexes. Specifically: In Aim 1, we will identify Api-derived peptides with improved activity upon ribosomes from
Gram-negative and Gram-positive pathogens. In Aim 2, the spectrum of action of Api-like peptides will be expanded by
bypassing the necessity for uptake by the SbmA transporter. Finally, in Aim 3, we will broaden the variety of natural
antimicrobial peptides that have the ability to inhibit translation termination. All of the Aims are independent from each other,
but the specific implementation of experiments planned for each aim could be influenced by the results emerging from the
other aims. The reagents and tools that will be generated in the course of the proposed work will serve as leads for future
clinical development. Importantly, the results obtained in the proposed studies will significantly advance the general field of
ribosome-targeting antibacterial peptides, which currently is still in its infancy.

## Key facts

- **NIH application ID:** 10436039
- **Project number:** 1R56AI162961-01
- **Recipient organization:** UNIVERSITY OF ILLINOIS AT CHICAGO
- **Principal Investigator:** ALEXANDER S MANKIN
- **Activity code:** R56 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2021
- **Award amount:** $730,027
- **Award type:** 1
- **Project period:** 2021-07-16 → 2022-02-07

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10436039

## Citation

> US National Institutes of Health, RePORTER application 10436039, Advancing ribosome-targeting antibacterial peptides with a unique mechanism of action (1R56AI162961-01). Retrieved via AI Analytics 2026-08-21 from https://api.ai-analytics.org/grant/nih/10436039. Licensed CC0.

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