# Chemical biology of type IV secretion systems

> **NIH NIH P20** · UNIVERSITY OF KENTUCKY · 2022 · $299,064

## Abstract

PROJECT SUMMARY
Bacteria have evolved specialized nanomachines to deliver microbial cargo across the cell envelope. One
versatile translocation apparatus, the type IV secretion system (T4SS), can be strategically deployed to inject
macromolecular substrates into target bacterial or eukaryotic recipient cells. Despite their importance in bacterial
pathogenesis and dissemination of antibiotic resistance determinants, the mechanisms by which the T4SS
assembles and transports payload remain largely undefined. To address this knowledge gap, the long-term goal
of this proposal is to develop and apply robust molecular tools to accelerate fundamental studies of T4SS
nanomachines. The cag T4SS of the gastric bacterium Helicobacter pylori has emerged as an important system
for understanding how a single molecular machine can transport diverse cargo into target cells. Whereas some
T4SS have the capacity to secrete hundreds of proteins or DNA-protein complexes into the host cell, the ability
to translocate a diverse repertoire of lipid, nucleic acid, protein, and polysaccharide substrates distinguishes the
cag T4SS from other systems. Notably, the bacterial oncoprotein CagA is rapidly delivered to host gastric cells
via cag T4SS mechanisms. Translocated H. pylori effector molecules activate innate defenses and dysregulate
signaling pathways that influence progression of gastric disease; consequently, colonization by cag T4SS-
positive H. pylori significantly augments the risk for gastric cancer. As a result of its central role in bacterial
pathogenesis, the T4SS represents an ideal target for antimicrobials. In this application, we propose to identify
and mechanistically characterize novel small molecule-based T4SS modulators. Iterative structure-activity
relationship studies will be used to develop chemical scaffolds and pharmacophores with optimized anti-virulence
potential. Probe development will take advantage of expertise and assay platforms in the Shaffer lab and will
leverage synergistic resources in the proposed CPRI Computational Core (ligand-binding model development,
rational design, virtual screening), CPRI Translational Core (high throughput assay support, novel compound
repositories, and ADMET profiling), and the Organic Synthesis Core (medicinal chemistry and scale-up).
Prioritized and validated chemical probes will be used in conjunction with biochemical and genetic approaches
to interrogate cag T4SS regulation and dynamic steps in substrate translocation. Using a similar multidisciplinary
approach, we will determine how the H. pylori cag T4SS apparatus assembles at the bacteria-host cell interface.
Collectively, these studies will stimulate new basic research directions and will provide important insight into how
the T4SS nanomachine orchestrates the delivery of specific molecular cargo to target cells to drive microbial
pathogenesis. Furthermore, this work will generate powerful chemical tools that are broadly applicable to
infectious disea...

## Key facts

- **NIH application ID:** 10333392
- **Project number:** 5P20GM130456-03
- **Recipient organization:** UNIVERSITY OF KENTUCKY
- **Principal Investigator:** Carrie Shaffer
- **Activity code:** P20 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2022
- **Award amount:** $299,064
- **Award type:** 5
- **Project period:** 2020-03-01 → 2025-01-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10333392

## Citation

> US National Institutes of Health, RePORTER application 10333392, Chemical biology of type IV secretion systems (5P20GM130456-03). Retrieved via AI Analytics 2026-05-22 from https://api.ai-analytics.org/grant/nih/10333392. Licensed CC0.

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