# Peptidoglycan Fragment Library to Investigate Innate Immune Responses

> **NIH NIH R01** · UNIVERSITY OF DELAWARE · 2023 · $489,153

## Abstract

PROJECT SUMMARY
Bacterial cells surround themselves with a peptidoglycan (PG) cell wall, an essential structure that resists
changes in osmotic pressure and other environmental insults. The goal of this proposal is to develop a PG
fragment library that captures the natural diversity to facilitate the proper innate and adaptive immunity
biological studies. PG fragments are used by the innate immune system to correctly recognize and respond to
the presence of bacteria. We hypothesize that PG diversity naturally present across the multitude of bacterial
species is essential for generating the correct immune response for host defense. Study of these important
PG fragments has been hampered by the lack of reproducible, high purity compounds. Currently, researchers
are limited to few carbohydrate probes, such as MDP, and even fewer larger fragments. We propose to
functionalize three carbohydrate cores: monosaccharide, disaccharide and peptide dimers, with select amino
acids which are highly represented across a variety of bacterial species. The synthetic workflow is modular,
builds off our expertise in producing highly pure PG fragments and permits for modification with chemical
biology probes at multiple pinpoints on the library members. A large PG fragment library of this type has not
been produced before. To overcome this challenge we propose to use common intermediates for all three
carbohydrate cores. We aim to use this library to interrogate innate immune responses elicited in
macrophages. In Aim One, a large-scale, modular synthetic effort will be undertaken to produce the >400
member library. For Aim Two the disaccharide and peptide linked dimer family members will be employed in
an unbiased genome wide transcriptome analysis to unravel gene expression signatures that define the
responses to PG classes in bone marrow derived macrophages. We will synthesize the chemical biology
probes to investigate receptors and signaling partners. Aim Three will probe the innate immune response of
the PG through the production of a PG-microarray. This array will fix the PG derivatives in multiple orientations
permitting the sweeping of potential receptors across chemical space. The arrays will be used to assess the
substrate binding preferences of a variety of innate immune receptors indicated in PG recognition. This library
will accurately capture the PG fragment diversity, providing powerful probes for the proposed immunological
assays and new tools for the microbial and immunological communities.

## Key facts

- **NIH application ID:** 10620744
- **Project number:** 5R01GM138599-04
- **Recipient organization:** UNIVERSITY OF DELAWARE
- **Principal Investigator:** Catherine Leimkuhler Grimes
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2023
- **Award amount:** $489,153
- **Award type:** 5
- **Project period:** 2020-08-03 → 2025-05-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10620744

## Citation

> US National Institutes of Health, RePORTER application 10620744, Peptidoglycan Fragment Library to Investigate Innate Immune Responses (5R01GM138599-04). Retrieved via AI Analytics 2026-05-24 from https://api.ai-analytics.org/grant/nih/10620744. Licensed CC0.

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