# Regulation of mycobacterial adaptive mistranslation

> **NIH NIH R56** · UNIVERSITY OF CALIFORNIA, SAN FRANCISCO · 2024 · $679,658

## Abstract

PROJECT SUMMARY
Mycobacterium tuberculosis (Mtb), the causative agent of tuberculosis (TB) uses regulation of specific translation
error rates – mistranslation – to survive a variety of stressors including antibiotics and the host environment.
Both too high and too low mistranslation rates can be detrimental to the pathogen. However, it is not known how
Mtb regulates translational error. Understanding the regulation of mistranslation by Mtb will allow for the
development of targeted therapies that interfere with Mtb’s tolerance to antibiotics and survival within the host.
The source of adaptive mistranslation in Mtb is the indirect tRNA aminoacylation pathway: used for the cognate
synthesis of aminoacylated glutamine and asparagine tRNAs, and which results in high levels of mischarged
glutamine and asparagine tRNAs. This pathway is present in most pathogens with the exception of Escherichia
coli. Using forward genetics and small molecule screens, we have identified drugs and genetic mutations that
are implicated in Mtb’s regulation of high mistranslation rates. The aminoglycoside kasugamycin (Ksg) can
decrease specific mistranslation rates in Mtb but has very limited anti-microbial activity and has a very high
minimum inhibitory concentration (MIC) against Mtb growth in vitro. When given at subMIC concentrations to
Mtb-infected mice, Ksg can, as a single agent, attenuate Mtb survival; and when given in combination, can
substantially potentiate anti-TB drugs. Similarly, deletion of the 16S rRNA methyltransferase GidB allows
low/moderate levels of mistranslation but prevents runaway catastrophic mistranslation. Both of these
perturbations affect the ribosome. This is intriguing because prior studies on ribosomes had suggested that
ribosomes do not discriminate against mischarged tRNAs. A potential explanation may be that those prior studies
were performed exclusively with ribosomes from E. coli – which, unlike Mtb, doesn’t routinely encounter
mischarged tRNAs. To understand the mechanisms by which the Mtb translational apparatus can discriminate
against mischarged tRNAs we will use biochemical, structural and kinetic approaches. We will solve the structure
of Mtb ribosomes +/- Ksg or +/- GidB-mediated methylation to identify how these ribosomal perturbations affect
ribosomal recognition of, and discrimination of mischarged tRNAs. Using single molecule fluorescence
resonance energy transfer (smFRET), we will identify the steps in the translation cycle in which ribosomes can
proofread against mischarged tRNA-mediated mistranslation. Together, these studies will a) allow mechanistic
insight into an important non-genetic and non-transcriptional mechanism by which Mtb survives diverse
stressors, b) provide greater understanding of Mtb ribosome function and the translation cycle, which is likely to
be substantially different from model organisms, and c) permit the future development of structure- and
biochemical-informed therapies that target Mtb adaptiv...

## Key facts

- **NIH application ID:** 11101479
- **Project number:** 1R56AI185094-01
- **Recipient organization:** UNIVERSITY OF CALIFORNIA, SAN FRANCISCO
- **Principal Investigator:** Babak Javid
- **Activity code:** R56 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2024
- **Award amount:** $679,658
- **Award type:** 1
- **Project period:** 2024-08-16 → 2026-07-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/11101479

## Citation

> US National Institutes of Health, RePORTER application 11101479, Regulation of mycobacterial adaptive mistranslation (1R56AI185094-01). Retrieved via AI Analytics 2026-05-24 from https://api.ai-analytics.org/grant/nih/11101479. Licensed CC0.

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