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Updated: May 5, 2026
FLIM-FRET Measurements of Protein-Protein Interactions in Live Bacteria.
Published on: August 25, 2020
Evaluation of a FRET-peptide substrate to predict virulence in Pseudomonas aeruginosa
Wendy E Kaman1, Nora El Arkoubi-El Arkoubi, Sanne Roffel
1Department of Medical Microbiology and Infectious Diseases, Erasmus Medical Center, Rotterdam, The Netherlands ; Department of Oral Biochemistry, Academic Centre for Dentistry Amsterdam, University of Amsterdam and VU University Amsterdam, Amsterdam, The Netherlands.
Abstract:
Pseudomonas aeruginosa produces a number of proteases that are associated with virulence and disease progression. A substrate able to detect P. aeruginosa-specific proteolytic activity could help to rapidly alert clinicians to the virulence potential of individual P. aeruginosa strains. For this purpose we designed a set of P. aeruginosa-specific fluorogenic substrates, comprising fluorescence resonance energy transfer (FRET)-labeled peptides, and evaluated their applicability to P. aeruginosa virulence in a range of clinical isolates. A FRET-peptide comprising three glycines (3xGly) was found to be specific for the detection of P. aeruginosa proteases. Further screening of 97 P. aeruginosa clinical isolates showed a wide variation in 3xGly cleavage activity. The absence of 3xGly degradation by a lasI knock out strain indicated that 3xGly cleavage by P. aeruginosa could be quorum sensing (QS)-related, a hypothesis strengthened by the observation of a strong correlation between 3xGly cleavage, LasA staphylolytic activity and pyocyanin production. Additionally, isolates able to cleave 3xGly were more susceptible to the QS inhibiting antibiotic azithromycin (AZM). In conclusion, we designed and evaluated a 3xGly substrate possibly useful as a simple tool to predict virulence and AZM susceptibility.
Insights
A novel fluorogenic substrate, 3xGly, detects Pseudomonas aeruginosa proteases, potentially predicting bacterial virulence and antibiotic susceptibility. This tool aids clinicians in assessing infection risk and guiding treatment decisions.
Area of Science:
- Microbiology
- Biochemistry
- Clinical Diagnostics
Background:
- Pseudomonas aeruginosa proteases are key virulence factors.
- Rapid detection of P. aeruginosa virulence is clinically important.
- Existing methods for assessing virulence factors can be time-consuming.
Purpose of the Study:
- To design and evaluate a P. aeruginosa-specific fluorogenic substrate for detecting proteolytic activity.
- To assess the correlation between substrate cleavage and bacterial virulence.
- To investigate the relationship between substrate cleavage and antibiotic susceptibility.
Main Methods:
- Design and synthesis of fluorescence resonance energy transfer (FRET)-labeled peptides.
- Screening of 97 clinical isolates of P. aeruginosa using the 3xGly FRET-peptide.
- Assay of LasA staphylolytic activity and pyocyanin production.
- Testing susceptibility to azithromycin (AZM) in relation to 3xGly cleavage.
Main Results:
- A 3xGly FRET-peptide specifically detected P. aeruginosa proteases.
- Significant variation in 3xGly cleavage activity was observed among clinical isolates.
- 3xGly cleavage correlated with LasA activity, pyocyanin production, and quorum sensing (QS).
- Isolates cleaving 3xGly showed increased susceptibility to azithromycin.
Conclusions:
- The 3xGly substrate is a potential tool for rapid assessment of P. aeruginosa virulence.
- 3xGly cleavage may serve as a biomarker for QS-related virulence.
- This substrate could help predict susceptibility to QS-inhibiting antibiotics like azithromycin.
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