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Acinetobacter spp. porin Omp33-36: Classification and transcriptional response to carbapenems and host cells
Katarina Novović1, Sanja Mihajlović1, Miroslav Dinić1
1Institute of Molecular Genetics and Genetic Engineering, University of Belgrade, Belgrade, Serbia.
Abstract:
Acinetobacter baumannii has been recognized as one of the most challeging pathogens in clinical settings worldwide. Outer membrane porins play a significant role in Acinetobacter antibiotic resistance and virulence. A. baumannii carbapenem resistance and virulence factor porin Omp33-36 was the subject of this study. We investigated the omp33-36 gene transcriptional response in the growth phase, its response to carbapenems, and the effect of contact with host cells. Additionally, the cytotoxic effect of A. baumannii towards keratinocytes was assessed, as well as correlation between omp33-36 gene transcription and cytotoxicity. Further, Acinetobacter spp. Omp33-36 was classified and its characteristics relevant for vaccine candidature were determined. The level of the omp33-36 gene transcription varied between growth phases, but a common pattern could not be established among different strains. Treatment with subinhibitory concentrations of carbapenems decreased, while contact with keratinocytes increased omp33-36 expression in the analysed A. baumannii strains. Variations in omp33-36 mRNA levels did not correlate with cytotoxicity levels. Decrease of omp33-36 mRNA during treatment with subinhibitory concentrations of carbapenems, indicated the importance of transcriptional changes in reversible resistance to carbapenems due to the absence of Omp33-36. The transcription of omp33-36 increased after contact with keratinocytes, indicating the important role of de novo transcription during the initial phase of A. baumannii infection. Primary structural analysis of Acinetobacter spp. Omp33-36 revealed three distinct groups (among four A. baumannii variants). Although we have shown that Omp33-36 was highly polymorphic, we propose a potential antigen (PLAEAAFL motif) for vaccine development. According to PROVEAN analysis, the highly polymorphic structure of Omp33-36 porin should not influence its function significantly.
Insights
Acinetobacter baumannii outer membrane porin Omp33-36's gene expression changes with growth, carbapenems, and host cell contact. This porin shows potential as a vaccine target despite its variability.
Area of Science:
- Microbiology
- Molecular Biology
- Immunology
Background:
- Acinetobacter baumannii is a critical global pathogen.
- Outer membrane porins are key to A. baumannii's antibiotic resistance and virulence.
- The Omp33-36 porin is implicated in carbapenem resistance and virulence.
Purpose of the Study:
- Investigate the omp33-36 gene's transcriptional response during growth, carbapenem exposure, and host cell interaction.
- Assess A. baumannii cytotoxicity towards keratinocytes and its correlation with omp33-36 transcription.
- Characterize Acinetobacter spp. Omp33-36 for vaccine development potential.
Main Methods:
- Gene transcription analysis across different growth phases and conditions.
- Exposure of A. baumannii to subinhibitory carbapenem concentrations and keratinocytes.
- Cytotoxicity assays using keratinocytes.
- Bioinformatic analysis of Acinetobacter spp. Omp33-36 sequences.
Main Results:
- Omp33-36 transcription varied with growth phase and strain.
- Carbapenem treatment decreased omp33-36 expression; keratinocyte contact increased it.
- No correlation was found between omp33-36 mRNA levels and cytotoxicity.
- Omp33-36 exhibited significant polymorphism, with a potential vaccine antigen (PLAEAAFL motif) identified.
Conclusions:
- Transcriptional changes in omp33-36 are crucial for reversible carbapenem resistance.
- Increased omp33-36 transcription upon host cell contact highlights its role in early infection.
- Omp33-36 is a promising candidate for A. baumannii vaccine development despite its structural diversity.
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