# Evolution and consequences of multidrug resistant ribosome

> **NIH NIH R01** · NORTHWESTERN UNIVERSITY · 2024 · $463,374

## Abstract

ABSTRACT
 Posttranscriptional modifications of bacterial and eukaryotic ribosomes are linked to many human
diseases, but the precise role of most modifications remains undefined. Dimethylation of a universally
conserved adenine, A2058, in bacterial rRNA causes cross-resistance against all three critically
important families of antibiotics (macrolides, lincosamides, and streptogramins (MLS)). A2058
dimethylation occludes MLS from the ribosome, thereby allowing normal protein biosynthesis and
bacterial growth. The thirty-five classes of Erm methyltransferases responsible for A2058 dimethylation
are invariantly encoded by a two-gene operon preceded by a short ribosome stalling leader sequence.
These short stalling peptides considerably vary in size and sequence composition. The functional and
evolutionary connections between the stalling sequence and its cognate erm gene are poorly understood.
A previous `ribosome stalling' model suggests that macrolide-mediated translational stalling of the leader
sequence is required for the upregulation of downstream co-transcribed erm, but clinical surveillance and
our data indicate the existence of an alternative pathway. Our unpublished data further show that
collateral sensitivity to unrelated antibiotics, reduction in virulence gene expression, accumulation of
inactive ribosomes, and loss of in vivo fitness are all part of the trade-offs associated with the A2058
dimethylated ribosome. The exact mechanistic links between these traits are unknown. There is also an
unmet need to understand the mechanism by which Erm recognizes and acts on 23S rRNA. This
proposal will use a multi-pronged approach consisting of high-precision next-generation sequencing,
bacterial genetics, proteomics, comparative genomics, biochemistry and structural biology to address
three central questions: What are the underlying mechanisms of the trade-offs conferred by the A2058
dimethylated ribosome? How does the erm operon evolve, and how is the expression of erm regulated?
How does Erm find its target substrate RNA? The erm operons are widespread among nosocomial
Gram-negative and Gram-positive bacteria, addressing these questions will offer significant mechanistic
insight into new antimicrobial strategies tailored to disrupt these biochemical interactions and regulatory
pathways.

## Key facts

- **NIH application ID:** 10902117
- **Project number:** 5R01AI150986-05
- **Recipient organization:** NORTHWESTERN UNIVERSITY
- **Principal Investigator:** M.-N. Frances Yap
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2024
- **Award amount:** $463,374
- **Award type:** 5
- **Project period:** 2020-09-16 → 2026-08-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10902117

## Citation

> US National Institutes of Health, RePORTER application 10902117, Evolution and consequences of multidrug resistant ribosome (5R01AI150986-05). Retrieved via AI Analytics 2026-05-23 from https://api.ai-analytics.org/grant/nih/10902117. Licensed CC0.

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