# Exploration of the genetic interaction between secreted virulence determinants from pathogenic mycobacteria

> **NIH NIH R21** · UNIVERSITY OF NOTRE DAME · 2020 · $193,125

## Abstract

PROJECT SUMMARY
The ESX-1 (ESAT-6 system-1) secretion system is essential for mycobacterial pathogenesis. Yet, the specific
role of the ESX-1 secreted proteins (substrates) in protein secretion and virulence remains unclear. Because the
inactivation of individual ESX-1 substrate genes reportedly results in the same phenotype, genetic approaches
have provided little information regarding the functional roles of ESX-1 substrates. Without understanding the
contribution of ESX-1 substrates, the field faces a major hurdle in understanding the mechanisms underlying
ESX-1-mediated secretion and virulence. The applicant's long-term goal is to understand the molecular
mechanisms underlying mycobacterial protein secretion. The objective of this proposal is to uncover the
functional relationships between ESX-1 substrates. The rationale underlying the proposal is that the successful
completion of the proposed research will provide basic insight into the relationship between ESX-1 substrates,
providing a new framework for understanding ESX-1 secretion. The applicant's lab has uncovered that the
deletion of individual ESX-1 substrate genes results in discrete phenotypes that have been previously missed.
The central hypothesis of the proposal is that by leveraging the unique secretory phenotypes associated with
the deletion of individual and pairs of genes encoding substrates, fundamental but elusive aspects of ESX-1
protein secretion can be defined. The central hypothesis will be tested by these specific aims: 1). Define the
requirement of each substrate in ESX-1 secretion. 2) Define the functional relationship between ESX-1
substrates. Under Aim 1, the applicant proposes a quantitative proteomics approach to measure the changes in
ESX-1-mediated protein secretion due to the loss of individual ESX-1 substrates. Under Aim 2, the applicant
proposes to define genetic relationships between ESX-1 substrates by measuring how pairwise deletion of ESX-
1 substrate genes impacts mycobacterial secretion and virulence. Understanding how individual substrates
promote ESX-1 secretion and virulence is significant because it will open new avenues for investigation into how
each ESX-1 substrate promotes secretion and virulence, which could inform the treatment and prevention of
mycobacterial infections. The proposed research is innovative because it challenges the status quo by providing
a means to define discrete phenotypes of and functional relationships between ESX-1 substrates. Collectively,
the completion of both aims will advance the field vertically by defining fundamental but elusive features of the
mechanistic biology underlying ESX-1 protein secretion.

## Key facts

- **NIH application ID:** 9856981
- **Project number:** 5R21AI142127-02
- **Recipient organization:** UNIVERSITY OF NOTRE DAME
- **Principal Investigator:** Patricia A Champion
- **Activity code:** R21 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2020
- **Award amount:** $193,125
- **Award type:** 5
- **Project period:** 2019-02-01 → 2023-01-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/9856981

## Citation

> US National Institutes of Health, RePORTER application 9856981, Exploration of the genetic interaction between secreted virulence determinants from pathogenic mycobacteria (5R21AI142127-02). Retrieved via AI Analytics 2026-05-23 from https://api.ai-analytics.org/grant/nih/9856981. Licensed CC0.

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