Crystallization and preliminary X-ray diffraction analysis of gingipain R2 from Porphyromonas gingivalis in complex with H-D-Phe-Phe-Arg-chloromethylketone

Periodontal microbiology and microbial etiology of periodontal diseases: Historical concepts and contemporary perspectives

This narrative review summarizes the collective knowledge on periodontal microbiology, through a historical timeline that highlights the European contribution in the global field. The etiological concepts on periodontal disease culminate to the ecological plaque hypothesis and its dysbiosis-centered interpretation. Reference is made to anerobic microbiology and to the discovery of select periodontal pathogens and their virulence factors, as well as to biofilms. The evolution of contemporary molecular methods and high-throughput platforms is highlighted in appreciating the breadth and depth of the periodontal microbiome. Finally clinical microbiology is brought into perspective with the contribution of different microbial species in periodontal diagnosis, the combination of microbial and host biomarkers for this purpose, and the use of antimicrobials in the treatment of the disease.

Cleavage of extracellular matrix in periodontitis: gingipains differentially affect cell adhesion activities of fibronectin and tenascin-C

Gingipains are cysteine proteases that represent major virulence factors of the periodontopathogenic bacterium Porphyromonas gingivalis. Gingipains are reported to degrade extracellular matrix (ECM) of periodontal tissues, leading to tissue destruction and apoptosis. The exact mechanism is not known, however. Fibronectin and tenascin-C are pericellular ECM glycoproteins present in periodontal tissues. Whereas fibronectin mediates fibroblast adhesion, tenascin-C binds to fibronectin and inhibits its cell-spreading activity. Using purified proteins in vitro, we asked whether fibronectin and tenascin-C are cleaved by gingipains at clinically relevant concentrations, and how fragmentation by the bacterial proteases affects their biological activity in cell adhesion. Fibronectin was cleaved into distinct fragments by all three gingipains; however, only arginine-specific HRgpA and RgpB but not lysine-specific Kgp destroyed its cell-spreading activity. This result was confirmed with recombinant cell-binding domain of fibronectin. Of the two major tenascin-C splice variants, the large but not the small was a substrate for gingipains, indicating that cleavage occurred primarily in the alternatively spliced domain. Surprisingly, cleavage of large tenascin-C variant by all three gingipains generated fragments with increased anti-adhesive activity towards intact fibronectin. Fibronectin and tenascin-C fragments were detected in gingival crevicular fluid of a subset of periodontitis patients. We conclude that cleavage by gingipains directly affects the biological activity of both fibronectin and tenascin-C in a manner that might lead to increased cell detachment and loss during periodontal disease.

Cysteine proteases of Porphyromonas gingivalis

The cysteine proteases of Porphyromonas gingivalis are extracellular products of an important etiological agent in periodontal diseases. Many of the in vitro actions of these enzymes are consistent with the observed deregulated inflammatory and immune features of the disease. They are significant targets of the immune responses of affected individuals and are viewed by some as potential molecular targets for therapeutic approaches to these diseases. Furthermore, they appear to represent a complex group of genes and protein products whose transcriptional and translational control and maturation pathways may have a broader relevance to virulence determinants of other persistent bacterial pathogens of human mucosal surfaces. As a result, the genetics, chemistry, and virulence-related properties of the cysteine proteases of P. gingivalis have been the focus of much research effort over the last ten years. In this review, we describe some of the progress in their molecular characterization and how their putative biological roles, in relation to the in vivo growth and survival strategies of P. gingivalis, may also contribute to the periodontal disease process.

Arginine-specific cysteine proteinase from porphyromonas gingivalis as a convenient tool in protein chemistry

RgpB, a cysteine proteinase produced by Porphyromonas gingivalis, exhibits proteolytic activity selectively directed against peptide bonds containing an arginine residue in the P1 position. Here we show that this enzyme can be used for very efficient and specific protein cleavage. RgpB is highly active even at high concentrations of denaturing agents, including urea (up to 6 M) and SDS (0.1%), both of them being commonly used for solubilization of insoluble proteins and peptides. Moreover, RgpB is able to digest polypeptide chains in buffers supplemented with 1% Triton X-100, 1% octyl or decylpyranoside, detergents employed for the enzymatic digestion of proteins transferred onto nitrocellulose membranes. These features render RgpB a suitable tool for use in protein chemistry.