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Multiple colonization defects in a cysteine protease mutant of Porphyromonas gingivalis
H Kuramitsu1, M Tokuda, M Yoneda
1Department of Oral Biology, State University of New York, Buffalo, USA.
Abstract:
A cysteine protease mutant, G-102, of Porphyromonas gingivalis 381 defective in the rgp-1 gene has been recently constructed in this laboratory. In order to evaluate the role of the protease in the virulence properties of P. gingivalis, a number of putative periodontopathic properties of the mutant were evaluated. Relative to the parental strain, mutant G-102 was demonstrated to be defective in interacting with Gram-positive bacteria as well as cultured epithelial cells. In addition, the mutant was altered in attaching to the protein components of extracellular matrix as well as to type I collagen. Some of these alterations could result from the decreased autoaggregation displayed by mutant G-102 relative to strain 381. However, since the epithelial cell attachment assays were carried out at very low bacterial densities, it is unlikely that reduced autoaggregation of the mutant is responsible for its decreased ability to attach to these eucaryotic cells. Electron microscopic examination of the cells also revealed that mutant G-102 was altered in normal fimbrae expression. In addition, reduced expression of the 43 kDa fimbrial subunit in the mutant was detected with both Western and Northern blotting. These results indicated that the rgp-1 gene product can play either a direct or indirect role in the colonization properties of P. gingivalis.
Insights
A mutant of Porphyromonas gingivalis lacking the rgp-1 gene showed reduced virulence. This cysteine protease mutant (G-102) had impaired interactions with host cells and extracellular matrix, suggesting rgp-1’s role in bacterial colonization.
Area of Science:
- Microbiology
- Oral Health Research
- Bacterial Pathogenesis
Background:
- Porphyromonas gingivalis is a key pathogen in periodontitis.
- Cysteine proteases, particularly Rgp-1, are implicated in P. gingivalis virulence.
- Understanding the specific roles of virulence factors is crucial for developing targeted therapies.
Purpose of the Study:
- To investigate the role of the rgp-1 gene product in the virulence of Porphyromonas gingivalis.
- To evaluate the impact of a specific rgp-1 mutant (G-102) on key periodontopathic properties.
Main Methods:
- Construction of a P. gingivalis mutant (G-102) defective in the rgp-1 gene.
- Assessment of bacterial interactions with Gram-positive bacteria and epithelial cells.
- Evaluation of adherence to extracellular matrix proteins and type I collagen.
- Analysis of autoaggregation, fimbrial expression, and gene/protein levels via Western and Northern blotting.
Main Results:
- Mutant G-102 exhibited reduced interaction with Gram-positive bacteria and epithelial cells compared to the parent strain.
- Attachment to extracellular matrix components and type I collagen was significantly altered in the mutant.
- Decreased autoaggregation was observed in G-102, but unlikely to explain reduced epithelial cell attachment.
- Electron microscopy revealed altered fimbrial expression, with reduced 43 kDa fimbrial subunit levels confirmed by blotting.
Conclusions:
- The rgp-1 gene product plays a significant role in the virulence of Porphyromonas gingivalis.
- Defects in rgp-1 affect bacterial adherence, autoaggregation, and fimbrial expression.
- These findings suggest rgp-1 is involved directly or indirectly in the colonization capabilities of P. gingivalis.