# C-terminal proteolysis in the Pseudomonas aeruginosa cell envelope

> **NIH NIH R01** · NEW YORK UNIVERSITY SCHOOL OF MEDICINE · 2021 · $606,027

## Abstract

PROJECT SUMMARY
The bacterium Pseudomonas aeruginosa is a common opportunistic human pathogen that causes life-
threatening illnesses, including acute pneumonia, long-term lung colonization in most cystic fibrosis patients,
and severe wound infections, especially in hospitalized patients and those with severe burns. Most P.
aeruginosa infections are associated with compromised host defense and this, together with the common
environmental occurrence of the organism, makes it a frequent cause of sepsis in the intensive care unit. The
resolution of P. aeruginosa disease is challenging, in part because of its intrinsic resistance to antibiotics as well
as occasional outbreaks of multi-drug-resistant strains in hospitals. Therefore, there is an urgent need to identify
new targets for therapeutic attack. The cell envelope of P. aeruginosa has two C-terminal processing proteases
or CTPs (named CtpA and Prc), both of which have been linked to systems associated with disease. In fact,
many bacterial CTPs have been linked to virulence but very little is known about the underlying mechanisms. In
P. aeruginosa, CtpA is essential for protein export by a machine known as a type 3 secretion system, one of the
most important virulence systems for acute infections. Prc has been linked to a regulatory system that controls
the production of a surface molecule known as alginate, which is associated with a poor prognosis in cystic
fibrosis patients. We have now discovered that CtpA forms a complex with an uncharacterized outer membrane
lipoprotein, which facilitates its activity. This proteolytic complex targets at least one enzyme that modifies the
bacterial cell wall. We hypothesize that many other bacterial CTPs, including Prc in P. aeruginosa, will also
work with partner proteins to target cell wall modifying enzymes, which makes an understanding of how these
proteolytic complexes function broadly significant. Therefore, in this work we will: (1) Analyze how the
lipoprotein partner facilitates CtpA-dependent proteolysis; (2), Investigate the impact of a CtpA substrate on the
cell wall and virulence, and how its proteolysis is controlled within the bacterial cell; (3) Broaden the impact of
this work by characterizing additional CtpA substrates and testing our hypothesis that Prc functions similarly.
We predict that CTPs will emerge as a conserved mechanism by which bacteria regulate some of their cell wall
modifying enzymes. Therefore, not only will this work provide insight into how CTPs function, which will be of
relevance to many pathogens, but it will also shed light on how bacteria control the metabolism of one of their
most clinically important components, the cell wall. Finally, the accessible cell envelope proteins that we
characterize here could eventually be considered as new targets for therapeutic drugs.

## Key facts

- **NIH application ID:** 10072026
- **Project number:** 5R01AI136901-04
- **Recipient organization:** NEW YORK UNIVERSITY SCHOOL OF MEDICINE
- **Principal Investigator:** ANDREW J. DARWIN
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2021
- **Award amount:** $606,027
- **Award type:** 5
- **Project period:** 2018-01-01 → 2023-12-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10072026

## Citation

> US National Institutes of Health, RePORTER application 10072026, C-terminal proteolysis in the Pseudomonas aeruginosa cell envelope (5R01AI136901-04). Retrieved via AI Analytics 2026-05-23 from https://api.ai-analytics.org/grant/nih/10072026. Licensed CC0.

---

*[NIH grants dataset](/datasets/nih-grants) · CC0 1.0*