Roles of Porphyromonas gulae proteases in bacterial and host cell biology

Area of Science:

• Microbiology
• Periodontology
• Molecular Biology

Background:

• Porphyromonas gulae is an animal-derived periodontal pathogen.
• Virulence factors include fimbria, lipopolysaccharide (LPS), and proteases.
• Previous studies linked fimbriae to invasion and LPS to inflammation.

Purpose of the Study:

• Investigate the role of P. gulae proteases in bacterial and host cell biology.
• Determine the effect of proteases on bacterial aggregation and host cell functions.

Main Methods:

• Assessed haemagglutination and co-aggregation with Actinomyces viscosus.
• Utilized protease inhibitors (antipain, PMSF, TLCK, leupeptin) to evaluate protease activity.
• Measured inhibition of Ca9-22 cell proliferation and protein degradation.
• Analyzed changes in cell morphology and adhesion-related proteins (E-cadherin, β-catenin, focal adhesion kinase).

Main Results:

• P. gulae proteases mediated haemagglutination and co-aggregation.
• Protease inhibitors reduced proteolytic activity, haemagglutination, co-aggregation, and bacterial growth.
• P. gulae inhibited Ca9-22 cell proliferation and altered cell morphology.
• Protease activity degraded host proteins like E-cadherin, β-catenin, and focal adhesion kinase.
• Inhibition of protease activity prevented protein degradation and cell proliferation inhibition.
• P. gulae proteases suppressed human proteins including γ-globulin, fibrinogen, and fibronectin.

Conclusions:

• P. gulae proteases play a significant role in bacterial virulence.
• Protease activity contributes to bacterial aggregation and host cell dysfunction.
• A novel protease complex in P. gulae may be a key virulence factor.