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Membrane protein expression by Actinobacillus actinomycetemcomitans in response to iron availability
J L Winston1, C K Chen, M E Neiders
1Department of Oral Biology, State University of New York at Buffalo 14214-3092.
Journal of Dental Research
|October 1, 1993
Summary
Actinobacillus actinomycetemcomitans expresses a 70-kDa iron-repressible protein under both aerobic and anaerobic conditions. This protein, potentially involved in iron transport, is recognized by patient sera, suggesting in vivo expression during periodontitis.
Area of Science:
- Microbiology
- Molecular Biology
- Periodontal Disease Pathogenesis
Background:
- Actinobacillus actinomycetemcomitans is a bacterium implicated in periodontal diseases.
- Iron is an essential nutrient for bacterial growth and virulence.
- Understanding bacterial iron acquisition mechanisms is crucial for developing therapeutic strategies.
Purpose of the Study:
- To investigate the iron-regulated protein expression in Actinobacillus actinomycetemcomitans under different growth conditions.
- To determine if the identified iron-repressible protein is expressed in vivo.
- To explore potential iron transport systems utilized by A. actinomycetemcomitans.
Main Methods:
- Establishing iron-limited growth conditions using specific iron chelators (2,2'-dipyridyl for anaerobiosis, EDDA for aerobiosis).
- Analyzing sarcosyl-insoluble membrane fractions to identify iron-repressible proteins via SDS-PAGE.
- Utilizing patient and healthy subject sera for Western blot analysis to detect protein expression in vivo.
- Investigating siderophore production and iron-binding protein interactions (transferrin, lactoferrin).
Main Results:
- A conserved, iron-repressible protein of approximately 70 kDa was identified in iron-stressed anaerobic and aerobic cultures of A. actinomycetemcomitans strains.
- This 70-kDa protein was recognized by serum from localized juvenile periodontitis patients and healthy individuals, indicating potential in vivo expression.
- No significant siderophore production or binding to transferrin/lactoferrin was observed in iron-starved cells, suggesting alternative iron uptake mechanisms.
Conclusions:
- Actinobacillus actinomycetemcomitans produces a 70-kDa iron-repressible protein that is likely involved in iron acquisition.
- The in vivo expression of this protein suggests its role in the pathogenesis of periodontitis.
- Further research is needed to elucidate the specific iron transport mechanisms employed by this bacterium.