Comparative proteomics of inner membrane fraction from carbapenem-resistant Acinetobacter baumannii with a reference
Vishvanath Tiwari1, Jitendraa Vashistt, Arti Kapil
1Department of Biochemistry, All India Institute of Medical Sciences, Ansari Nagar, New Delhi, India.
Abstract:
Acinetobacter baumannii has been identified by the Infectious Diseases Society of America as one of the six pathogens that cause majority of hospital infections. Increased resistance of A.baumannii even to the latest generation of β-lactams like carbapenem is an immediate threat to mankind. As inner-membrane fraction plays a significant role in survival of A.baumannii, we investigated the inner-membrane fraction proteome of carbapenem-resistant strain of A.baumannii using Differential In-Gel Electrophoresis (DIGE) followed by DeCyder, Progenesis and LC-MS/MS analysis. We identified 19 over-expressed and 4 down-regulated proteins (fold change>2, p<0.05) in resistant strain as compared to reference strain. Some of the upregulated proteins in resistant strain and their association with carbapenem resistance in A.baumannii are: i) β-lactamases, AmpC and OXA-51: cleave and inactivate carbapenem ii) metabolic enzymes, ATP synthase, malate dehydrogenase and 2-oxoglutarate dehydrogenase: help in increased energy production for the survival and iii) elongation factor Tu and ribosomal proteins: help in the overall protein production. Further, entry of carbapenem perhaps is limited by controlled production of OmpW and low levels of surface antigen help to evade host defence mechanism in developing resistance in A.baumannii. Present results support a model for the importance of proteins of inner-membrane fraction and their synergistic effect in the mediation of resistance of A.baumannii to carbapenem.
Insights
Carbapenem-resistant Acinetobacter baumannii survival is linked to inner-membrane proteins. Upregulated proteins like beta-lactamases and metabolic enzymes contribute to resistance, while OmpW and surface antigens may limit drug entry and immune evasion.
Area of Science:
- Microbiology
- Proteomics
- Infectious Diseases
Background:
- Acinetobacter baumannii is a critical hospital pathogen.
- Carbapenem resistance in A. baumannii poses a significant global health threat.
- The inner membrane is crucial for A. baumannii survival.
Purpose of the Study:
- To investigate the proteome of the inner membrane in carbapenem-resistant A. baumannii.
- To identify proteins associated with carbapenem resistance.
Main Methods:
- Differential In-Gel Electrophoresis (DIGE) was used to compare protein expression.
- Liquid Chromatography-Mass Spectrometry/Mass Spectrometry (LC-MS/MS) identified proteins.
- Bioinformatic analysis (DeCyder, Progenesis) quantified protein changes.
Main Results:
- 19 proteins were over-expressed and 4 were down-regulated in the resistant strain (fold change > 2, p < 0.05).
- Upregulated proteins include beta-lactamases (AmpC, OXA-51), metabolic enzymes (ATP synthase, malate dehydrogenase, 2-oxoglutarate dehydrogenase), and protein synthesis factors (elongation factor Tu, ribosomal proteins).
- Down-regulated proteins potentially include OmpW, affecting carbapenem entry, and surface antigens involved in immune evasion.
Conclusions:
- Inner membrane proteins play a synergistic role in mediating carbapenem resistance in A. baumannii.
- Upregulated metabolic and resistance enzymes, alongside altered outer membrane protein production, contribute to survival and resistance.
- Targeting these inner membrane proteins could offer new strategies against resistant A. baumannii infections.
