Global comparison of the membrane subproteomes between a multidrug-resistant Acinetobacter baumannii strain and a
Axel Siroy1, Pascal Cosette, Damien Seyer
1IBBR Group, Laboratory Polymères, Biopolymères, Membranes, UMR 6522 CNRS, University of Rouen, France.
Abstract:
Acinetobacter baumannii causes severe infections in compromised patients. We combined SDS-PAGE, two-dimensional gel electrophoresis and mass spectrometry (LC-MS/MS and MALDI-TOF) to separate and characterize the proteins of the cell envelope of this bacterium. In total, 135 proteins (inner and outer membrane proteins) were identified. In this analysis, we described the expression by this bacterium of RND-type efflux systems and some potential virulence factors. We then compared the membrane subproteome of a clinical multidrug-resistant (MDR) isolate with that of a reference strain. We found that the MDR strain expressed lower levels of the penicillin-binding-protein 1b, produced a CarO protein having different primary and quaternary structures to that of the reference strain, and expressed OmpW isoforms. We also showed that the clinical strain has a high ability to form biofilms consistent with the accumulation of some outer membrane proteins (OMPs) such as NlpE or CsuD that have already been described as involved in bacterial adhesion. These features may partly explain the MDR emergence of the clinical isolate.
Insights
This study identifies 135 cell envelope proteins in Acinetobacter baumannii, revealing differences in a multidrug-resistant (MDR) strain. These changes, including altered proteins and biofilm formation, may explain its resistance.
Area of Science:
- Microbiology
- Proteomics
- Infectious Diseases
Background:
- Acinetobacter baumannii is a significant cause of severe infections, particularly in immunocompromised patients.
- Understanding the bacterial cell envelope is crucial for developing new therapeutic strategies against resistant strains.
Purpose of the Study:
- To characterize the cell envelope proteome of Acinetobacter baumannii.
- To compare the membrane subproteome of a multidrug-resistant (MDR) clinical isolate with a reference strain.
- To identify potential factors contributing to multidrug resistance and virulence.
Main Methods:
- Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE)
- Two-dimensional gel electrophoresis
- Liquid chromatography-tandem mass spectrometry (LC-MS/MS)
- Matrix-assisted laser desorption/ionization-time of flight (MALDI-TOF) mass spectrometry
Main Results:
- Identification of 135 inner and outer membrane proteins.
- The MDR strain exhibited lower penicillin-binding protein 1b levels and structural variations in the CarO protein compared to the reference strain.
- The MDR strain showed increased expression of OmpW isoforms and outer membrane proteins (OMPs) like NlpE and CsuD, associated with biofilm formation and adhesion.
Conclusions:
- The observed proteomic differences, including altered OMPs and enhanced biofilm formation, may contribute to the multidrug resistance of the clinical Acinetobacter baumannii isolate.
- This proteomic analysis provides insights into the mechanisms underlying Acinetobacter baumannii pathogenesis and resistance.
- Targeting these identified proteins could offer novel therapeutic avenues against Acinetobacter baumannii infections.
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