Multiple forms of proteases of Bacteroides gingivalis and their cellular location

Proteolytic Activities of Oral Bacteria on ProMMP-9 and the Effect of Synthetic Proteinase Inhibitors

Tissue reactions to bacteria lead to proinflammatory reactions involving matrix metalloproteinases (MMPs). Synthetic protease inhibitors may offer new possibilities to regulate bacterial proteases. We investigated proteolytic activities of certain periodontal bacteria, their effects on the latent proMMP-9, and the effects of synthetic MMP inhibitors and a serine protease inhibitor Pefabloc. The strains studied were Porphyromonas gingivalis, Prevotella intermedia, Peptostreptoccus micros, Prevotella nigrescens, Fusobacterium nucleatum, and 5 Aggregatibacter actinomycetemcomitans serotypes. Their gelatinolytic activities and the effects of certain synthetic MMP inhibitors and Pefabloc were analyzed by zymography. Bacterial effects on proMMP-9 conversion were investigated by Western immunoblot. All investigated periodontal bacteria produced gelatinolytic cell-bound and extracellular proteinases which could fragment latent proMMP-9, suggesting co-operative processing cascades in oral tissue remodeling. A. actinomycetemcomitans produced the weakest gelatinolytic activity. Synthetic proteinase inhibitors exhibited slight but clear reductive effects on the bacterial proteolytic activities. We conclude that targeted anti-proteolytic treatment modalities against bacterial-host proteolytic cascades can be developed.

Inhibitory effect of cranberry polyphenol on biofilm formation and cysteine proteases of Porphyromonas gingivalis

BACKGROUND AND OBJECTIVE

The purpose of this study was to investigate the effects of cranberry polyphenol fraction on biofilm formation and activities of Arg-gingipain and Lys-gingipain in Porphyromonas gingivalis.

MATERIAL AND METHODS

The polyphenol fraction was prepared by using a glass column packed with Amberlite XAD 7HP and 70% aqueous ethanol as an elution solvent.

RESULTS

Synergistic biofilm formation by P. gingivalis and Fusobacterium nucleatum was significantly inhibited by the polyphenol fraction at a concentration of 250 microg/mL compared with untreated controls (p < 0.01). Arg-gingipain and Lys-gingipain activities in P. gingivalis ATCC 33277 and FDC 381 were inhibited significantly at a polyphenol fraction concentration of > or = 1 microg/mL (p < 0.05).

CONCLUSION

These findings indicate that the polyphenol fraction inhibits biofilm formation and the Arg-gingipain and Lys-gingipain activities of P. gingivalis.

Antibody Responses of Periodontitis Patients to Gingipains ofPorphyromonas gingivalis

BACKGROUND

Arginine- and lysine-specific cysteine proteinases (arg-gingipain: Rgp, lys-gingipain: Kgp) are major virulence factors of Porphyromonas gingivalis. Recent reports have suggested that antibodies against gingipains can play a protective role against infection by P. gingivalis. The purpose of this study was to evaluate the IgG responses of patients with periodontitis to functional domains of gingipains.

METHODS

A group of 29 periodontitis patients and 10 periodontally healthy subjects (control group) were recruited into this study. We prepared three recombinant fragments of rgp A (catalytic domain; r-Rgp CAT) and two hemagglutinin domains (r-Rgp 44, and r-Rgps 15-27) corresponding to amino acid residues 228 to 719, 720 to 1136, and 1137 to 1704, respectively. One fragment of the Kgp catalytic domain (r-Kgp CAT) corresponding to amino acid residues 229 to 737 and expressed in Escherichia coli was also used. IgG antibody levels to these recombinant proteins in sera from the subjects were determined by an enzyme-linked immunosorbent assay (ELISA).

RESULTS

We found that IgG levels against r-Rgp 44 and r-Rgps 15-27 in sera obtained from the patients were significantly higher than those in the healthy group (P<0.01). In contrast, no significant differences in IgG levels against r-Rgp CAT and r-Kgp CAT were found between the control and patient groups. The IgG responses to P. gingivalis sonic extracts, r-Rgp 44 and r-Rgps 15-27, were related to probing depth in sera from patients, but those to r-Rgp CAT and r-Kgp CAT were not.

CONCLUSION

The present findings suggest that the low responsiveness of IgG antibody against the catalytic domains of gingipain, r-Rgp CAT, and r-Kgp CAT is a key factor in infection by P. gingivalis.

Arg-gingipain a DNA vaccine induces protective immunity against infection by Porphyromonas gingivalis in a murine model

Arginine-specific cysteine proteinases (RgpA and RgpB) produced by the periodontal pathogen Porphyromonas gingivalis are suspected virulence factors and are involved in interrupting host defense mechanisms as well as in penetrating and destroying periodontal connective tissues. To induce a protective immune response against P. gingivalis, we constructed an rgpA DNA vaccine. BALB/c mice were immunized intradermally by Gene Gun with plasmid DNA carrying rgpA. Antibody responses against P. gingivalis were determined by an enzyme-linked immunosorbent assay. The rgpA DNA vaccine induced high levels of serum antibodies against P. gingivalis. Sera from the rgpA DNA vaccine-immunized mice diminished the proteolytic activity of RgpA and RgpB and inhibited the binding of P. gingivalis to a type I collagen sponge. Moreover, the sera effectively reduced the hemagglutination of P. gingivalis, indicating that the hemagglutinin activity of the organism is associated with RgpA. We found with a murine abscess model that mice immunized with the rgpA DNA vaccine were resistant to an invasive P. gingivalis W50 challenge. These results suggest that the rgpA DNA vaccine induced specific antibodies against the enzyme and that this vaccine could confer protective immunity against P. gingivalis infection.

Porphyrin-mediated binding to hemoglobin by the HA2 domain of cysteine proteinases (gingipains) and hemagglutinins from the periodontal pathogen Porphyromonas gingivalis

Heme binding and uptake are considered fundamental to the growth and virulence of the gram-negative periodontal pathogen Porphyromonas gingivalis. We therefore examined the potential role of the dominant P. gingivalis cysteine proteinases (gingipains) in the acquisition of heme from the environment. A recombinant hemoglobin-binding domain that is conserved between two predominant gingipains (domain HA2) demonstrated tight binding to hemin (Kd = 16 nM), and binding was inhibited by iron-free protoporphyrin IX (Ki = 2.5 microM). Hemoglobin binding to the gingipains and the recombinant HA2 (rHA2) domain (Kd = 2.1 nM) was also inhibited by protoporphyrin IX (Ki = 10 microM), demonstrating an essential interaction between the HA2 domain and the heme moiety in hemoglobin binding. Binding of rHA2 with either hemin, protoporphyrin IX, or hematoporphyrin was abolished by establishing covalent linkage of the protoporphyrin propionic acid side chains to fixed amines, demonstrating specific and directed binding of rHA2 to these protoporphyrins. A monoclonal antibody which recognizes a peptide epitope within the HA2 domain was employed to demonstrate that HA2-associated hemoglobin-binding activity was expressed and released by P. gingivalis cells in a batch culture, in parallel with proteinase activity. Cysteine proteinases from P. gingivalis appear to be multidomain proteins with functions for hemagglutination, erythrocyte lysis, proteolysis, and heme binding, as demonstrated here. Detailed understanding of the biochemical pathways for heme acquisition in P. gingivalis may allow precise targeting of this critical metabolic aspect for periodontal disease prevention.

Some binding properties of the envelope of Porphyromonas gingivalis to hemoglobin

Porphyromonas gingivalis was found to bind to hemoproteins (hemoglobin, myoglobin, catalase, cytochrome c) and the binding properties of the envelope of P. gingivalis to hemoglobin were investigated. Maximum amount of hemoglobin bound to 1 mg of the envelope was 58 micrograms. No significant binding was observed at 4 degrees C and the binding was inhibited strongly by tosyl-L-lysine chloromethyl ketone, Leupeptin, EDTA and partially by meta-periodate. Heating of the envelope at 70 degrees C for 15 min resulted in complete loss of the binding activity. The binding activity of the envelope was not influenced by the treatment with the endogenous proteases. The envelope saturated with hemoglobin could no longer bind to other hemoproteins tested, indicating that binding site for these hemoproteins are common.

Selective growth inhibition of Porphyromonas gingivalis by bestatin

Recent work in our laboratory indicates that selected protease/peptidase inhibitors interfere with the growth of Porphyromonas gingivalis. The aim of the present study was to further investigate the inhibitory effect of bestatin on the growth of P. gingivalis. Complete growth inhibition of P. gingivalis (11 strains) was observed when bestatin was incorporated at 2.5 micrograms ml-1 in a complex broth medium. Fifty percent inhibition was still obtained with bestatin at a final concentration of 0.5 microgram ml-1. The inhibitory effect of bestatin was highly specific as the growth of 20 different oral bacterial species, including Gram-positive and Gram-negative as well as saccharolytic and asaccharoltic bacteria, was not affected even at bestatin concentrations up to 50 micrograms ml-1. Bestatin did not significantly affect the viability of P. gingivalis indicating that it has a bacteriostatic rather than a bactericidal effect. Growth assays using other specific inhibitors suggested that the effect of bestatin on the growth of P. gingivalis was unlikely to be related to its aminopeptidase inhibitor activity. Cultivation of P. gingivalis with a subinhibitory concentration of bestatin did not modify the cell envelope protein profile, as determined by SDS-PAGE analysis, but significantly decreased the number of extracellular vesicles produced. The present study indicated that bestatin is a highly effective inhibitor of cell growth of P. gingivalis. Additional studies will indicate whether bestatin should be considered as a potential drug in the control of P. gingivalis, a suspected pathogen in adult chronic periodontitis.

Comparative studies of three proteases of Porphyromonas gingivalis

Three thiol-activated proteases, designated Qa, Ra, and Sa, in the soluble fraction of the cell extract of Porphyromonas gingivalis ATCC 33277 were purified by combinations of gel filtration, ion exchange chromatography and electrophoresis, and characterized. The molecular weights estimated by gel filtration method were 43 kDa (Sa), 87 kDa (Ra), and 170 kDa (Qa). However, they were found to have the same molecular weight (43 kDa), when estimated by SDS-PAGE, indicating that Sa is a monomeric, Ra is a dimeric and Qa is a tetrameric form. The 3 enzymes showed quite similar biochemical properties, and they could degrade not only the synthetic substrates but immunoglobulins, fibrinogen and albumin.

Purification and characterization of a 43-kDa protease of Bacteroides gingivalis

From the culture supernatant of Bacteroides gingivalis ATCC 33277, a thiol protease was purified to homogeneity by fractional ammonium sulfate precipitation, ion-exchange chromatography, gel filtration, and isoelectric focusing. Its molecular weight was 43 kDa and showed similar enzymatic properties to a 300-kDa protease that was previously characterized.