Gingipains from Porphyromonas gingivalis - Complex domain structures confer diverse functions.

Area of Science:

• Microbiology
• Structural Biology
• Biochemistry

Background:

• Gingipains (RgpA, RgpB, Kgp) are critical virulence factors of Porphyromonas gingivalis, a pathogen causing chronic periodontitis.
• These cysteine proteinases mediate bacterial adherence, immune evasion, and tissue damage through various functions, including haemagglutination and host protein degradation.

Purpose of the Study:

• To propose a new domain model for the haemagglutinin/adhesin (HA) regions of gingipains.
• To challenge the existing gingipain domain structure hypothesis with an alternative modular architecture.

Main Methods:

• Analysis of multiple sequence alignments and hidden Markov models to predict domain organization.
• Examination of crystal structures of recombinant cleaved adhesin domains (K2, K3).

Main Results:

• An alternative domain model suggests HA regions are composed of repeating "cleaved adhesin" domains.
• Crystal structures confirm the stability and modularity of these putative adhesin domains.
• It is proposed that all cleaved adhesin domains share a common β-sandwich jelly roll fold.

Conclusions:

• The new domain model provides a refined understanding of gingipain structure.
• This revised model will guide future functional and structural studies of P. gingivalis virulence factors.