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Isolation and Characterization of Extracellular Vesicles Produced by Iron-limited Mycobacteria
Published on: October 31, 2019
Molecular cloning and characterization of a 79-kDa iron-repressible outer-membrane protein of Moraxella bovis
Tsutomu Kakuda1, Daiki Oishi, Shiro Tsubaki
1Department of Animal Hygiene, School of Veterinary Medicine and Animal Science, Kitasato University, Towada, Aomori 034-8628, Japan. kakuda@vmas.kitasato-u.ac.jp
Abstract:
Moraxella bovis expresses an iron-repressible 79-kDa outer-membrane protein, IrpA. DNA and N-terminal amino acid sequence analysis indicate that IrpA is closely related to FrpB of Neisseria meningitidis, FetA of Neisseria gonorrhoeae and CopB of Moraxella catarrhalis. The results of manganese mutagenesis and a gel-shift assay suggested that the transcription of irpA is negatively regulated by the ferric uptake regulator. The insertion of an antibiotic resistance cassette into the irpA gene affected the strain's ability to utilize bovine transferrin and lactoferrin. IrpA was detected in geographically diverse clinical isolates, and the antigenicity of IrpA was conserved in all the isolates tested. Therefore, IrpA may have potential as a candidate vaccine.
Insights
Moraxella bovis expresses an iron-repressible outer-membrane protein, IrpA, crucial for iron acquisition. This protein, conserved across isolates, shows potential as a vaccine candidate against bovine respiratory disease.
Area of Science:
- Microbiology
- Bacterial Pathogenesis
- Vaccine Development
Background:
- Moraxella bovis is a significant pathogen causing infectious bovine keratoconjunctivitis (IBK).
- Outer-membrane proteins play critical roles in bacterial survival and virulence.
- Iron acquisition is essential for bacterial growth, particularly in host environments.
Purpose of the Study:
- To characterize the iron-repressible outer-membrane protein IrpA from Moraxella bovis.
- To investigate the regulation of irpA gene expression.
- To assess the role of IrpA in iron utilization and its potential as a vaccine candidate.
Main Methods:
- DNA and N-terminal amino acid sequence analysis.
- Manganese mutagenesis and gel-shift assay for gene regulation studies.
- Antibiotic resistance cassette insertion to study gene function.
- Detection of IrpA in clinical isolates and assessment of antigenicity.
Main Results:
- IrpA is an iron-repressible 79-kDa outer-membrane protein closely related to similar proteins in Neisseria species.
- IrpA transcription is negatively regulated by the ferric uptake regulator.
- Disruption of the irpA gene impaired the utilization of bovine transferrin and lactoferrin.
- IrpA antigenicity was conserved in geographically diverse clinical isolates.
Conclusions:
- IrpA is a key component of Moraxella bovis's iron acquisition system.
- The ferric uptake regulator controls irpA expression.
- IrpA's conserved antigenicity and role in iron uptake suggest its potential as a vaccine candidate for preventing Moraxella bovis infections.
