A trypsin-like protease from Bacteroides gingivalis: partial purification and characterization

Activity-based protein profiling of serine hydrolases and penicillin-binding proteins in Enterococcus faecium

Enterococcus faecium is a gut commensal bacterium which is gaining increasing relevance as an opportunistic, nosocomial pathogen. Its high level of intrinsic and acquired antimicrobial resistance is causing a lack of treatment options, particularly for infections with vancomycin-resistant strains, and prioritizes the identification and functional validation of novel druggable targets. Here, we use activity-based protein profiling (ABPP), a chemoproteomics approach using functionalized covalent inhibitors, to detect active serine hydrolases across 11 E. faecium and Enterococcus lactis strains. Serine hydrolases are a big and diverse enzyme family, that includes known drug targets such as penicillin-binding proteins (PBPs), whereas other subfamilies are underexplored. Comparative gel-based ABPP using Bocillin-FL revealed strain- and growth condition-dependent variations in PBP activities. Profiling with the broadly serine hydrolase-reactive fluorescent probe fluorophosphonate-TMR showed a high similarity across E. faecium clade A1 strains, but higher variation across A2 and E. lactis strains. To identify these serine hydrolases, we used a biotinylated probe analog allowing for enrichment and identification via liquid chromatography-mass spectrometry. We identified 11 largely uncharacterized targets (α,β-hydrolases, SGNH-hydrolases, phospholipases, and amidases, peptidases) that are druggable and accessible in live vancomycin-resistant E. faecium E745 and may possess vital functions that are to be characterized in future studies.

Porphyromonas gingivalis influences actin degradation within epithelial cells during invasion and apoptosis

Porphyromonas gingivalis, a Gram-negative oral pathogen, has been shown to induce apoptosis in human gingival epithelial cells, yet the underlining cellular mechanisms controlling this process are poorly understood. We have previously shown that the P. gingivalis proteases arginine and lysine gingipains, are necessary and sufficient to induce host cell apoptosis. In the present study, we demonstrate that 'P. gingivalis-induced apoptosis' is mediated through degradation of actin leading to cytoskeleton collapse. Stimulation of human gingival epithelial cells with P. gingivalis strains 33277 and W50 at moi:100 induced β-actin cleavage as early as 1 h and human serum inhibited this effect. By using gingipain-deficient mutants of P. gingivalis and purified gingipains, we demonstrate that lysine gingipain is involved in actin hydrolysis in a dose and time-dependent manner. Use of Jasplakinolide and cytochalasin D revealed that P. gingivalis internalization is necessary for actin cleavage. Further, we also show that lysine gingipain from P. gingivalis can cleave active caspase 3. Taken together, we have identified actin as a substrate for lysine gingipain and demonstrated a novel mechanism involved in microbial host cell invasion and apoptosis.

Determination of active site of lysine-specific cysteine proteinase (Lys-gingipain) by use of a Porphyromonas gingivalis plasmid system

Porphyromonas gingivalis, a major etiological bacterium of periodontal diseases, produces a unique lysine-specific cysteine proteinase (Lys-gingipain, Kgp) implicated in the virulence of this organism. Our observations show the expression of a catalytically active recombinant Kgp in a P. gingivalis Kgp-null mutant and the restoration of its functions by the use of a shuttle plasmid vector stable in P. gingivalis. The Kgp-expressing mutant exhibited a similar catalytic activity to that of the wild-type strain. This mutant also restored the ability to form black-pigmented colonies on blood agar plates and to generate a 19-kDa haemoglobin receptor protein responsible for haemoglobin binding. In order to establish the importance of the active-site Cys residue and elucidate its role in bacterial black pigmentation we constructed three Kgp mutants with changed potential active-site Cys residues. The cells expressing a single mutation (C476A) showed the high Kgp activity and the black pigmentation. In contrast, the cells expressing the single mutant (C477A) and the double mutant (C476A/C477A) exhibited neither Kgp activity nor black pigmentation. These results indicate that the 477th Cys residue is essential for both the Kgp activity and the black pigmentation of P. gingivalis.

Human beta-defensin-1 and -2 and matrix metalloproteinase-25 and -26 expression in chronic and aggressive periodontitis and in peri-implantitis

OBJECTIVE

Aberrant matrix metalloproteinase (MMP) and human beta-defensin (HBD) functions have been found in inflammatory diseases. The objectives of this study were to investigate the immunolocalisation, mRNA expression and molecular forms of MMP-25, MMP-26, HBD-1 and HBD-2 in chronic and aggressive periodontitis and in peri-implantitis. The expression of MMP-25 by cultured human plasmacytoma cells and macrophages, and the effects of MMP-26 and Porphyromonas gingivalis trypsin-like proteinase on HBD-1 and -2 were also studied.

DESIGN

Immunohistochemistry, immunofluorescent analysis, reverse transcriptase polymerase chain reaction and immunoblotting were used to assess localisation, mRNA expression and molecular forms of MMP-25, MMP-26, HBD-1 and HBD-2. HBD degradation by MMP-26 and P. gingivalis proteinase was studied by sodium dodecyl sulphate-polyacrylamide gel electrophoresis.

RESULTS

MMP-25 was present in plasma cells and polymorphonuclear leucocytes, and MMP-26 was present in oral and sulcular basement membrane zones. HBD-1 was distributed perivasculary in gingival connective tissue and in oral and sulcular epithelium, and HBD-2 was found to a lesser extent in the perivascular space. Low MMP-25, MMP-26, HBD-1 and HBD-2 mRNA expression was found. Immunoblot revealed 29-57-kDa MMP-25 in myeloma cell lysates, but not in macrophages, and partly activated MMP-25 and -26 in diseased gingival crevicular fluid and peri-implant sulcular fluid. P. gingivalis trypsin-like proteinase degraded HBD-1 and -2.

CONCLUSIONS

Both MMP-25 and -26 were expressed more strongly in extensively inflamed gingiva compared with healthy gingiva. The expression of HBD-1 was stronger than that of HBD-2 in periodontitis and peri-implantitis. De-novo expression of MMP-25 and -26 is associated with periodontal and peri-implant inflammation. Furthermore, P. gingivalis trypsin-like proteinase, but not MMP-26, can degrade HBD-1 and -2, which could lead to a weakened innate immune response.

Gingival crevicular fluid laminin-5 gamma2-chain levels in periodontal disease

AIM

Our study aimed to examine the molecular forms and gingival crevicular fluid (GCF) levels of laminin-5 gamma2-chain in patients with different periodontal disease, and compare the effects of P.gingivalis trypsin-like proteinase on intact laminin-5 gamma2-chain species.

METHODS

Eighteen patients with generalized aggressive periodontitis (G-AgP), 29 patients with chronic periodontitis (CP), 20 with gingivitis and 20 periodontally healthy subjects were included. Probing depth, clinical attachment loss, presence of bleeding on probing and plaque were recorded. Molecular forms and GCF laminin-5 gamma2-chain levels and the effects of P. gingivalis trypsin-like proteinase on intact laminin-5 gamma2-chain were analysed by computer-quantitated Western immunoblotting.

RESULTS

Laminin-5 gamma2-chain 40 and 70 kDa fragments could be detected in all groups, in varying levels. The CP group had elevated GCF laminin-5 gamma2-chain fragment levels compared with the gingivitis and healthy groups (p<0.008). The G-AgP group had GCF laminin-5 gamma2-chain fragment levels similar to the gingivitis and healthy groups (p>0.008). GCF laminin-5 gamma2-chain fragments differed clearly from the multiple lower molecular size fragments of P.gingivalis trypsin-laminin-5 gamma2-chain proteinases.

CONCLUSION

Increased GCF laminin-5 gamma2-chain fragments in periodontitis sites with deep periodontal pocket suggest that these cleaved 40 and 70 kDa fragments could reflect the extent of the inflammatory reaction in CP.

Matrix metalloproteinases (MMPs) in oral diseases

Matrix metalloproteinases (MMPs) are a group of enzymes that in concert are responsible for the degradation of most extracellular matrix proteins during organogenesis, growth and normal tissue turnover. The expression and activity of MMPs in adult tissues is normally quite low, but increases significantly in various pathological conditions that may lead into unwanted tissue destruction, such as inflammatory diseases, tumour growth and metastasis. MMPs have a marked role also in tissue destructive oral diseases. The role of collagenases, especially MMP-8, in periodontitis and peri-implantitis is the best-known example of the unwanted tissue destruction related to increased presence and activity of MMPs at the site of disease, but evidence has been brought forward to indicate that MMPs may be involved also in other oral diseases, such as dental caries and oral cancer. This brief review describes some of the history, the current status and the future aspects of the work mainly of our research groups looking at the presence and activity of various MMPs in different oral diseases, as well as some of the MMP-related aspects that may facilitate the development of new means of diagnosis and treatment of oral diseases.

Inhibition of proteolytic, serpinolytic, and progelatinase-b activation activities of periodontopathogens by doxycycline and the non-antimicrobial chemically modified tetracycline derivatives

BACKGROUND

Tetracyclines, particularly doxycycline (Doxy), and their non-antimicrobial chemically-modified derivatives (CMTs) inhibit the activities of human matrix metalloproteinases (MMPs), and reduce the severity and progression of periodontal disease in animal models and humans. In this study, the effects of Doxy and CMT-1, -3, and -5 on proteolytic, serpinolytic, and progelatinase-B activation activities of potent periodontopathogens were studied.

METHODS

The effect of Doxy and CMTs (0.5 to 50 microM) on proteolytic activities were investigated by incubating bacteria with chromogenic substrates or human serum albumin. A collagenolytic fraction of Porphyromonas gingivalis was used to evaluate the effect of these substances on collagenolytic (type I collagen) and serpinolytic (alpha1-proteinase inhibitor) activities. Lastly, the effect of Doxy on progelatinase-B (pro-MMP-9) activation by purified proteinases from P. gingivalis and Treponema denticola was investigated by SDS-PAGE/Western immunoblotting.

RESULTS

Doxy and CMTs, except CMT-5 which lacks the structural elements required for cation chelation, inhibited Arg- and Lys-gingipain activities as well as collagenolytic activity of P. gingivalis. Doxy and CMTs did not markedly affect the chymotrypsin-like activity of T. denticola but inhibited its trypsin-like activity. In addition, degradation of human serum albumin by cells of P. gingivalis and T. denticola was strongly inhibited by Doxy and CMT-1. Doxy and CMT-1 also inhibited the inactivation of alpha1-proteinase inhibitor (serpinolytic activity) by a collagenolytic fraction of P. gingivalis. Lastly, Doxy prevented the latent to active conversion of human neutrophil progelatinase-B (pro-MMP-9) by Arg-gingipains A/B of P. gingivalis but not by the chymotrypsin-like proteinase of T. denticola.

CONCLUSIONS

Data from this study suggest that Doxy and CMTs have the potential to inhibit the periodontopathogenic bacterial proteinases, which contribute to tissue destruction cascades during periodontitis directly and indirectly by triggering the host response.

Association of trypsin-2 with activation of gelatinase B and collagenase-2 in human bronchoalveolar lavage fluid in vivo

BACKGROUND

Tissue injury mediated by matrix metalloproteinases (MMPs) is a hallmark of inflammatory lung diseases. Latent secreted proMMPs must be activated to be catalytically competent.

AIM

Our aim was to analyse an involvement of the trypsin-2, trypsin-2-alpha1-proteinase inhibitor (PI) complex and tumour-associated trypsin inhibitor (TATI) in the in vivo activation of proMMP-8, -9 and -2.

METHODS

Concentrations of trypsin-2, trypsin-2-alpha1-PI complex and TATI in bronchoalveolar lavage fluid (BALF) were analysed by immunofluorometry. Molecular forms and expression of trypsin-2 and trypsin-2-alpha1-PI complex were identified by Western immunoblot and immunocytochemistry. Gelatinolytic and collagenolytic activities were measured by substrate-based activity assays.

RESULTS

BALFs from 16 of 43 patients and BALFs from five of 15 healthy controls contained trypsin-2-alpha1-PI complex. TATI was found in all healthy control BALFs (median 0.12 microg/L, range 0.02-0.66 microg/L) whereas 8 of 43 BALFs from patients (median 0, range 0-0.64 microg/L, P = 0.0001) contained TATI. Patient BALFs showed significantly increased activation of MMP-9 and MMP-8 compared with healthy controls. The concentrations of trypsin-2-alpha1-PI complex correlated with the in vivo activation of MMP-9 and -8 (r = 0.68, P = 0.002 and r = 0.61, P = 0.008) but not with the activation of MMP-2 in BALFs.

CONCLUSION

Results show a key role of trypsin-2 in the in vivo activation of proMMP-8 and -9 in inflammatory lung diseases.

Induction of matrix metalloproteinases and a collagen-degrading phenotype in fibroblasts and epithelial cells by secreted Porphyromonas gingivalis proteinase

Periodontitis is characterized by advancement of a narrow band of epithelium (1-10 cells wide) through the collagenous periodontal ligament in response to bacterial accumulation and infection. A modulating role by epithelial cells in the progression of periodontitis was hypothesized due to the close proximity of the advancing epithelium to both the etiological bacteria and to the collagen fibers of the ligament. We demonstrate that rat mucosal epithelial cells and human fibroblasts are similarly stimulated to degrade a collagen type I cellular substrate by thiol-dependent activity released by the major periodontal pathogen Porphyromonas gingivalis. A purified, extracellular bacterial thiol-proteinase from P. gingivalis ATCC 33277 stimulated mucosal epithelial cells to upregulate expression of collagenase and stromelysin, and to degrade a collagen type I fibril matrix. Stimulation of the epithelial cells with this purified proteinase was associated with morphological changes in the cells and with accumulation of secreted latent procollagenase throughout the culture medium. Release of active collagenase was minimal and collagen degradation by the epithelial cells was discreet and localized subcellularly suggesting the possibility that activation of secreted procollagenase was cell-associated. We conclude that a collagen-degrading phenotype can be stimulated in relatively quiescent mucosal epithelial cells and fibroblasts by the presence of bacterial proteinase. These experiments suggest roles for the P. gingivalis thiol-proteinase and the epithelial cell in the pathogenesis of periodontal disease and demonstrate the potential for dysregulation of extracellular matrix remodeling events during healing of other bacterially infected wounds.

Endopeptidase activities of selected Porphyromonas spp., Prevotella spp. and Fusobacterium spp. of oral and non-oral origin

The ability of three Porphyromonas spp., seven Prevotella spp., seven Fusobacterium spp. and two related Bacteroides spp. (B. levii and B. macacae) to degrade an extensive range of synthetic endo-, amino- and diamino peptidase substrates linked to the fluorescent leaving group 7-amido-4-methylcoumarin (NHMec) was investigated. Many more species than was previously recognized exhibited peptidase activities, albeit at lower levels than those already described for Porphyromonas gingivalis. Detection of chymotrypsin-like activity was dependent on which of three NHMec-linked substrates was used, but all species exhibited degradative activity with at least one of these substrates. Elastase-like activity was detected in all species though not all species reacted with each of the elastase substrates. Glycylprolyl peptidase activity was detected in all of the species tested with the exception of F. mortiferum, F. gonidiaformans, F. naviforme and F. necrophorum. While the detection of peptidase activities does not appear to be useful for the differentiation of species within the genera Bacteroides and Prevotella, its ability to differentiate species of the genus Porphyromonas or Fusobacterium warrants further investigation.

A cell-associated protein complex of Porphyromonas gingivalis W50 composed of Arg- and Lys-specific cysteine proteinases and adhesins

Porphyromonas gingivalis has been associated with the development of adult periodontitis and cysteine proteinases with trypsin-like specificity have been implicated as major virulence factors. We have extracted the major cell-associated trypsin-like proteolytic activity of P. gingivalis W50 using mild sonication. Anion-exchange and gel-filtration FPLC of the sonicate revealed that Arg- and Lys-specific proteinase activity was associated with a 300 kDa complex which could be dissociated into seven bands (48, 45, 44, 39, 27, 17 and 15 kDa) by SDS-PAGE with the 44 kDa band containing two different proteins as shown by N-terminal sequence analysis. On further chromatography of the 300 kDa complex on Arg-Sepharose the majority of the complex eluted from the affinity column as an undissociated complex. However, a small amount dissociated such that the Lys- and Arg-specific activities could be separated by eluting first with lysine then arginine, respectively. The 45 kDa protein of the complex was purified by further anion-exchange FPLC in the presence of octyl-beta-D-glucopyranoside and was shown to be an Arg-specific, thiol-activated, calcium-stabilized cysteine proteinase. The 48 kDa protein was also further purified in a similar fashion and shown to be a Lys-specific cysteine proteinase that was not inhibited by EDTA. The two 44 kDa and the 39, 27, 17 and 15 kDa proteins of the complex exhibit amino acid sequence homology and are proposed to be haemagglutinins/adhesins. The 45 kDa Arg-specific proteinase and one of the 44 kDa adhesins as well as the 15, 17 and 27 kDa adhesins are processed from the single polyprotein encoded by the gene designated prtR, with all proteins preceded by an Arg or Lys residue within the polyprotein. Similarly, the 48 kDa Lys-specific proteinase, the 39 and 15 kDa adhesins as well as the other 44 kDa adhesin of the 300 kDa complex are encoded by a single gene designated prtK, with all proteins preceded by an Arg or Lys residue within the polyprotein. The 39, 15 and 44 kDa adhesins of PrtK all exhibit high homology with the 44, 15, 17 and 27 kDa adhesins encoded by prtR, particularly the 15 kDa proteins which are identical. The cell-associated proteinase-adhesin complex, designated PrtR-PrtK, is therefore composed of the two gene products, the mature PrtR (160 kDa) and mature PrtK (163 kDa) that are further proteolytically processed (most likely autolytically) to release proteinase and adhesin domains that remain non-covalently associated. The fully processed PrtR-PrtK complex comprises the cysteine proteinases-PrtR45 and PrtK48 and seven sequence-related adhesin molecules, PrtR44, PrtR15, PrtR17, PrtR27 and PrtK39, PrtK15 and PrtK44. We propose that this proteinase-adhesin complex is a major virulence factor for P. gingivalis involved in the evasion of host defence and in the assimilation of haem and peptides.

Activation and novel processing of matrix metalloproteinases by a thiol-proteinase from the oral anaerobe Porphyromonas gingivalis

A critical outcome of periodontal disease is degradation of the collagenous periodontal ligament that connects teeth to bone in the dental arch. Periodontal diseases occur in response to bacterial colonization of the teeth, but their molecular pathogenesis is still speculative. One family of enzymes, known as the matrix metalloproteinases (MMPs), has been implicated in the degradation of the periodontal ligament. MMPs, which are also suspected to play a role in many other physiologic and pathologic remodeling processes, can be secreted by epithelial cells surrounding the teeth and are found in relative abundance in tissues and fluids near periodontally diseased sites. Since most MMPs are secreted as inactive zymogens which may be activated by limited proteolysis, it has been suggested that proteinases expressed by the infecting periodontal pathogens might activate latent host MMPs to initiate or accelerate degradation of the collegenous periodontal ligament. The aim of this work was to examine interactions between purified host MMPs and bacterial proteinase. In this article, we demonstrate that a proteinase isolated from the periodontopathogen Porphyromonas gingivalis can activate MMP-1, MMP-3, and MMP-9 and can catalyze the superactivation of MMP-1 by MMP-3. Activation of these MMPs is demonstrated to result from initial hydrolysis within their propeptide. Also, for MMP-1 and MMP-9, the P. gingivalis proteinase cleaves the MMP propeptide following a lysine residue at a previously unreported site which, for both MMPs, is one residue NH2-terminal to the known autocatalytic cleavage site. These data describe a mode of virulence for the periodontopathogen Porphyromonas gingivalis that involves activation of host-degradative enzymes.

Release and activation of human neutrophil matrix metallo- and serine proteinases during phagocytosis of Fusobacterium nucleatum, Porphyromonas gingivalis and Treponema denticola

The phagocytic ingestion of reference strains and clinical isolates of Fusobacterium nucleatum, Porphyromonas gingivalis, and Treponema denticola by polymorphonuclear leukocytes (PMNs) and the concomitant release of PMN granule proteinases were studied by specific functional and immunological assays. PMNs were incubated with the microorganisms anaerobically at 37 degrees C for indicated time periods. The suspensions and pellets were used for phagocytic ingestion assay and electron microscopic study, respectively. The supernatants were used for the measurements of the amounts and activities of the released PMN enzymes including PMN gelatinase (MMP-9), collagenase (MMP-8), serine proteases (elastase and cathepsin G), and lactate dehydrogenase (LDH). Both fluorescence microscopy and transmission electron microscopy showed that F. nucleatum, P. gingivalis and T. denticola were ingested by the PMNs in comparable numbers. However, measurements of the enzymes released from the triggered PMNs revealed major differences among the three species. High amount of elastase was released from the PMNs triggered by F. nucleatum, but not by P. gingivalis or T. denticola. The treatment of PMNs with P. gingivalis whole cells resulted in the release of gelatinase partly in the 82 kD active form, suggesting proteolytic activation of the degranulated 92 kD proMMP-9. The 82 kD active form of gelatinase was not detected upon triggering the PMNs with F. nucleatum and T. denticola. The PMN-bacteria interaction did not result in release of LDH from triggered PMNs indicating the proteinase release was not due to the PMN cell death. The results show that the susceptibilities of the 3 potentially periodontopathogenic microorganisms, F. nucleatum, P. gingivalis and T. denticola to phagocytic ingestion are not directly related to the amounts and activities of PMN enzymes released during the bacteria-PMN interactions. As PMN degranulation is considered as one of the major pathogenic mechanisms in periodontitis, the observed differences among the microorganisms may be important virulence characteristics of these species.

Inducible expression of a Porphyromonas gingivalis W83 membrane-associated protease

The Tpr protease of Porphyromonas gingivalis W83 is a membrane-associated enzyme capable of hydrolyzing a chromogenic bacterial collagenase substrate. An isogenic mutant lacking a functional tpr gene had a greatly reduced ability to hydrolyze the collagenase substrate. Activity was restored to the tpr mutant by introducing a shuttle plasmid containing the tpr gene. Expression of the gene is induced by nutrient limitation, as shown by enzymatic and Northern analyses.

Hemagglutinin activity and heterogeneity of related Porphyromonas gingivalis proteinases

Thiol-dependent proteinases that are expressed and released by Porphyromonas gingivalis are considered virulence factors in periodontitis because of their potential to effect matrix degradation and inflammation. A number of P. gingivalis thiol-proteinases have been described, however, with similar biochemical characteristics. In this report we demonstrate that an isolate P. gingivalis proteinase consists of noncovalently associated peptides and that slight variations in the association pattern of these peptides could result in different proteinases with different affinities and activities. We also describe the co-purification of thiol-proteinase activity with hemagglutinin activity and demonstrate that each type of activity has similar inhibition profiles. With the use of monoclonal antibodies against the P. gingivalis proteinase we follow proteinase released into the culture medium over the course of 10 days and, by Western blot analysis, demonstrate that many of the proteinases with varying molecular weight are related. The identification of a single, immunoreactive, 140 kDa proteinase detected early in the culture and in association with the P. gingivalis cells suggests that multiple proteinase may originate from a single 140 kDa proteinase.

Correlation between gingivain/gingipain and bacterial dipeptidyl peptidase activity in gingival crevicular fluid and periodontal attachment loss in chronic periodontitis patients. A 2-year longitudinal study

The aim of this study is to determine whether either gingival crevicular fluid (GCF) bacterial gingivain/gingipain or dipeptidyl peptidase (DPP) levels, total activity (TA) and concentration (EC), predict progressive attachment loss (AL) in 75 patients with moderate periodontitis. GCF was collected from 16 molar and premolar mesiobuccal sites and then clinical attachment level (CAL) and probing depth (PD) were measured with an electronic constant pressure probe. Lastly, gingival, gingival bleeding, and plaque indices were scored. Prior to the baseline visit, patients were given basic periodontal treatment after which the above procedures were repeated. In addition, carefully localized radiographs were taken of the test teeth and repeated annually. Patients were then seen every 3 months for 2 years and the clinical measurements repeated at each visit. In 48 patients, 124 AL sites, 91 rapid AL (RAL), and 33 gradual AL (GAL) were detected. Gingivain/gingipain and bacterial DPP levels (TA and EC) at RAL sites were significantly higher (P < or = 0.0001) than at paired control sites at the attachment loss time (ALT) and prediction time (PT). Mean levels over the study period of both proteases (TA and EC) at GAL sites were significantly higher (P < or = 0.0001) than those at paired control sites. The GCF levels of gingivain/gingipain were always higher than those of DPP. Critical values (CV) of 5 microU/30 seconds (TA) and 30 microU/microL (EC) for both proteases showed high sensitivity and specificity values for TA and EC, which were the same at both ALT and PT. The positive predictive values were higher for gingivain/ gingipain. Mean site levels, over the course of the study, of both proteases (TA and EC) were significantly higher (P < or = 0.0001) at AL, RAL, and GAL sites than non-attachment loss (NAL) sites in AL patients and mean patient levels were significantly higher (P < or = 0.0001) in AL, RAL, and GAL patients than NAL patients. These results indicate that both of these bacterial proteases in GCF may be predictors of periodontal attachment loss.

Binding and degradation of lactoferrin by Porphyromonas gingivalis, Prevotella intermedia and Prevotella nigrescens

The ability of laboratory and clinical strains of Porphyromonas gingivalis, Prevotella intermedia and Prevotella nigrescens to bind and to degrade lactoferrin (Lf) has been assessed. Lf bound readily to whole cells of each species apparently via high-affinity site and one or more low-affinity sites. P. gingivalis showed a lower affinity for Lf than the other two species (P < 0.001). Virtually all strains of P. gingivalis completely degraded Lf under the conditions employed, whereas P. intermedia and P. nigrescens showed only partial degradation. These data suggest that Lf binds to a high-affinity receptor on all these bacteria and, particularly in the case of P. gingivalis, is then degraded by cell-associated proteases. This property may provide protection to the cell against the effects of Lf in periodontal sites and so is a possible virulence factor in disease. There was no association between the ability to degrade Lf and whether the strains had originated from healthy or diseased oral sites.

Matrix metalloproteinases, gelatinase and collagenase, in chronic leg ulcers

Although extracellular proteolysis is a prerequisite for normal wound healing, uncontrolled proteolytic tissue destruction appears to be a pathogenic factor in non-healing wounds. The aim of our study was to compare the activities of the serine proteinases of polymorphonuclear origin, elastase and cathepsin G, and the metalloproteinases, gelatinase and collagenase, in chronic leg ulcer exudate (10 patients) and acute wound fluid (6 patients). Serine proteinase activities were low in leg ulcer exudates but very high in some but not all acute wound fluids. Total collagenase activity, measured as activity against type I collagen monitored by SDS-PAGE and densitometry, was higher in chronic leg ulcer exudate than in acute wound fluid and its degree of autoactivation was relatively high. Doxycycline inhibition studies suggested that the collagenase activity in chronic leg ulcer exudate was MMP-1 ("fibroblast-type") and not MMP-8 ("neutrophil-type"). Zymographic analysis of the gelatinolytic enzymes in acute wound fluid showed a progressive increase from the day of operation to postoperative day 5, but the degree of activity was lower than in chronic leg ulcer exudate and the low molecular mass activation products were faint. The leg ulcer gelatinase profiles were characterized by high expression of 92/82- and 72/62-kDa duplex bands and by the presence of low molecular mass activation products. Leg ulcer collagenase seems to be derived from mononuclear rather than polymorphonuclear cells, which are known to be involved in acute wound healing. In conclusion, the present study shows that gelatinase and collagenase, but not elastase and cathepsin G are found in chronic leg ulcer exudate.

Involvement of arginine-specific cysteine proteinase (Arg-gingipain) in fimbriation of Porphyromonas gingivalis

Arginine-specific cysteine proteinase (Arg-gingipain [RGP], a major proteinase secreted from the oral anaerobic bacterium Porphyromonas gingivalis, is encoded by two separate genes (rgpA and rgpB) on the P. gingivalis chromosome and widely implicated as an important virulence factor in the pathogenesis of periodontal disease (K. Nakayama, T. Kadowaki, K. Okamoto, and K. Yamamoto, J. Biol. Chem. 270:23619-23626, 1995). In this study, we investigated the role of RGP in the formation of P. gingivalis fimbriae which are thought to mediate adhesion of the organism to the oral surface by use of the rgp mutants. Electron microscopic observation revealed that the rgpA rgpB double (RGP-null) mutant possessed very few fimbriae on the cell surface, whereas the number of fimbriae of the rgpA or rgpB mutant was similar to that of the wild-type parent strain. The rgpB+ revertants that were isolated from the double mutant and recovered 20 to 40% of RGP activity of the wild-type parent possessed as many fimbriae as the wild-type parent, indicating that RGP significantly contributes to the fimbriation of P. gingivalis as well as to the degradation of various host proteins, disturbance of host defense mechanisms, and hemagglutination. Immunoblot analysis of cell extracts of these mutants with antifimbrilin antiserum revealed that the rgpA rgpB double mutant produced small amounts of two immunoreactive proteins with molecular masses of 45 and 43 kDa, corresponding to those of the precursor and mature forms of fimbrilin, respectively. The result suggests that RGP may function as a processing proteinase for fimbrilin maturation. In addition, a precursor form of the 75-kDa protein, one of the major outer membrane proteins of P. gingivalis, was accumulated in the rgpA rgpB double mutant but not in the single mutants and the revertants, suggesting an extensive role for RGP in the maturation of some of the cell surface proteins.

Modulation of host matrix metalloproteinases by bacterial virulence factors relevant in human periodontal diseases

OBJECTIVE

Bacterial pathogens involved in periodontal diseases exert a part of their destructive effect by triggering and inducing host cells to elevate their secretion of matrix metalloproteinases (MMPs). Pathogen-secreted phospholipase (PLC) is one bacterial product that may trigger this host response. The roles of exogenous PLC leading to the release, secretion and expression of MMPs by peripheral blood neutrophils (PMNs), cultured epithelial cells of human gingiva and porcine periodontal ligament were investigated. Also the activities of PLC in the diseased and healthy gingival sulcular fluid (crevicular fluid, GCF) and molecular forms of gelatinases present in dental plaque were investigated.

MATERIALS AND METHODS

GCF, salivary and dental plaque samples were analyzed for PLC and proteinase activities. The abilities of PLC to induce PMNs and oral epithelial cells to release and express their MMPs were examined by specific functional, immunological and molecular biology means.

RESULTS

PMN-derived MMPs were found to predominate in periodontitis GCF and plaque, and PLC activities were higher in GCF of adult periodontitis patients than in healthy controls. Purified bacterial PLC (1 mU ml(-1)) efficiently induced PMN degranulation. PLC also induced MMP expression in the cultured epithelial cells. The strongest response was seen in MMP-9 and less in MMP-2. The induction was dose-dependent in the range of 0.0-1.0 U ml(-1) PI-PLC, and quiescent cultures were more responsive than proliferating ones. PLC induction of MMPs was polar, with increased levels of MMP-9 in the apical region and increased MMP-2 levels secreted in the basal direction. Northern analysis showed a strong increase in mRNA levels of MMP-9 and a smaller increase for MMP-2 and MMP-1. In the second part of the study we investigated the molecular forms of the released MMPs during periodontitis. In bacterial plaque of periodontitis patients the MMP-9 were found to be converted into lower molecular weight forms. Isolated proteinase from Porphyromonas gingivalis (ATCC 33277) was able to convert human proMMPs to their active forms.

CONCLUSION

Bacterial PLC may induce degranulation of PMN MMPs and increase MMP expression in oral epithelial cells. The released proteases can be converted into active form by the proteases of plaque bacteria. Thereby, the pathogenic oral bacteria may indirectly participate in the destruction of periodontal tissues.

Construction and characterization of arginine-specific cysteine proteinase (Arg-gingipain)-deficient mutants of Porphyromonas gingivalis. Evidence for significant contribution of Arg-gingipain to virulence

Arginine-specific cysteine proteinase (Arg-gingipain; formerly, argingipain) is one of the major extracellular proteinases produced by the oral anaerobic bacterium Porphyromonas gingivalis. To determine whether Arg-gingipain is important for periodontopathogenicity of the organism, Arg-gingipain-deficient mutants were constructed via gene disruption by use of suicide plasmid systems. First, Southern hybridization analyses suggested that two separate Arg-gingipain-encoding genes designated rgpA and rgpB existed on 12.5- and 7.8-kilobase pair HindIII chromosomal fragments of P. gingivalis ATCC33277, respectively. rgpA and rgpB single mutants were constructed by mobilization of a suicide plasmid. Then, an rgpA rgpB double mutant was isolated by electroporation with a second suicide plasmid. No proteolytic activity for Arg-gingipain was observed in either the cell extract or the culture supernatant of the rgpA rgpB mutant. The chemiluminescence response of polymorphonuclear leukocytes, which is closely related to their bactericidal function, was not inhibited by the culture supernatant of the rgpA rgpA mutant, while the wild type parent showed a significant inhibition of the response. The result suggests that Arg-gingipain is responsible for disruption of the function of polymorphonuclear leukocytes. In addition, the rgpA rgpB double mutations caused a marked decrease in the hemagglutination of P. gingivalis, indicating that a major part of the hemagglutinin activity of the organism is associated with the two genes. These findings demonstrate that Arg-gingipain makes a significant contribution to the virulence of P. gingivalis.

Cellular source, activation and inhibition of dental plaque collagenase

Dental plaque is the major aetiological factor in periodontal diseases and contains several proteolytic enzymes. The origin of these proteinases is, however, poorly studied. This study was undertaken to characterize collagenase present in dental plaque of adult periodontitis patients. Vertebrate-type rather than bacterial-derived collagenase activity was detected in extracts of both supra- and subgingival dental plaque extracts of adult periodontitis patients. Dental plaque collagenase was found to exist predominantly in autoactive form. Dental plaque collagenase from periodontally healthy individuals existed in latent from. Latent dental plaque collagenase from periodontitis lesions could be activated by a 95 kD chymotrypsin-like proteinase from Treponema denticola and human leukocyte cathepsin G but not by human plasmin. Incubation of purified latent leukocyte collagenase with whole cells of Fusobacterium nucleatum, Eubacterium saburreum, Prevotella buccae and Porphyromonas gingivalis, however, did not result to the activation of the enzyme. Doxycycline in vitro inhibited dental plaque collagenase with an IC50-value of 20 microM. Dental plaque collagenase degraded more efficiently type I and II collagens than type III collagen. Western-blot analysis with specific anti-human neutrophil collagenase-antibody revealed that both in supra- and subgingival dental plaque extracts dental plaque collagenase had undergone proteolytic conversion from an 80 kD proform to a 58 kD active form which is associated with catalytic autoactivity as measured by functional collagenase assay. This reflects proteolytic activation of leukocyte collagenase in dental plaque probably by other proteases derived from potent periodontopathogenic bacteria such as T. denticola or other PMN proteases such as cathepsin G.(ABSTRACT TRUNCATED AT 250 WORDS)

Comparative study of four proteases from spent culture media of Porphyromonas gingivalis (FAY-19M-1)

Four gelatin cleaving proteases were partially purified from culture media of Porphyromonas gingivalis (FAY-19M-1) by sequential chromatography on columns of DEAE-Sepharose, Sephadex G-100 and chromatofocusing on PBE-94. The molecular mass of each of these proteases, estimated by relative mobility on gelatin-containing SDS-PAGE, was 50 kDa (Pool D1b), 120 kDa (Pool E1a), approximately 160 kDa (Pool E1b) and > 300 kDa (Pool A1a), respectively. These proteases also differed with respect to charge characteristics, inhibition profile and cleavage specificity. Protease pools A1a and E1a were inhibited by thiol modifying reagents. Protease pool A1a was also inhibited by N-tosyl-L-lysine chloromethyl ketone, and E1a was inhibited by antipain. Protease pool D1b was inhibited by E-64, leupeptin and antipain, and protease E1b was not inhibited by either of these inhibitors. The detailed substrate specificity of these proteases was checked by using chromogenic substrates, synthetic peptides and native proteins. Protease E1b was very active in degrading collagen, fibrinogen, fibronectin, IgG, IgA, third component of complement (C3), serum albumin, transferrin and varies; is directly proportional to 1-acid glycoprotein as substrates. Fibrinogen, fibronectin and complement C3 component were also cleaved by A1a, D1b and E1a. Synthetic peptides insulin B chain, cecropin P-1 and magainin were cleaved by E1b. Based on FAB analysis E1b showed preferential cleavage at hydrophobic or neutral residues. Protease A1a was active towards chromogenic substrates with either lys or arg in P1 position. Protease D1b cleaved chromogenic substrates with arg in P1 position and cleaved synthetic peptides magainin and (KIAGKIA)3-NH2 at lys residues also. Protease E1a showed glycyl-prolyl peptidase activity.

Human neutrophil collagenase (MMP-8), identified in bronchiectasis BAL fluid, correlates with severity of disease

Collagenases in bronchoalveolar lavage fluid (BALF) of patients with bronchiectasis and healthy subjects were characterized using specific functional and immunologic assays. The BAL fluid contained interstitial collagenase and collagenolytic proteinases of bacterial origin. Collagenase activities, obtained after organomercurial activation, correlated with the severity of bronchiectasis. In severe cases, collagenase activities were 3.5 x 10(-7) IU/L/48 h or 4.8 x 10(-6) IU/g/48 h (p < 0.01), in moderate ones 1.74 x 10(-7) IU/L/48 h or 3.35 x 10(-6) IU/g/48 h (p < 0.05), and in mild cases 0.32 x 10(-7) IU/L/48 h or 0.7 x 10(-6) IU/g/48 h (p < 0.05). The corresponding activities in healthy control subjects were 0.08 x 10(-7) IU/L/48 h or 0.13 x 10(-6) IU/g/48 h. The cellular origin of interstitial collagenase was assessed with doxycycline inhibition test utilizing the differential sensitivity of fibroblast-type collagenase/MMP-1 (IC50 = 280 microM) and neutrophil-type collagenase/MMP-8 (IC50 = 26 microM) to the anticollagenolytic, nonantimicrobial doxycycline action. Interstitial collagenase, contained in BALF, was totally inhibited by 100 microM of doxycycline. It can therefore be concluded that most of mammalian collagenase presented in inflamed fluid of bronchiectasis originated from neutrophils. The molecular forms of neutrophil-type collagenase/MMP-8 were confirmed and analyzed by Western-blot, which showed evidence of the proteolytic conversion of the latent 85-kD MMP-8 proenzyme species into active 65-kD molecular weight species. These findings strongly suggest involvement of proteolytic activation pathway of proMMP-8, especially in severe and moderate forms of bronchiectasis. Furthermore, collagenolytic proteases of bacterial origins may also participate in tissue destruction of the lung.

The multiple forms of trypsin-like activity present in various strains of Porphyromonas gingivalis are due to the presence of either Arg-gingipain or Lys-gingipain

Porphyromonas gingivalis contains high concentrations of numerous cysteine proteinases with trypsin-like activity which have been implicated as important virulence factors in adult-onset periodontitis. We have analyzed the subfractions of six P. gingivalis strains for the presence of arginine-X- and lysine-X-specific proteinases (Arg-gingipain [RGP] and Lys-gingipain [KGP]) previously purified from P. gingivalis H66. Western blot (immunoblot) analysis using antibodies produced against RGP and the N-terminal peptides of RGP or the catalytic subunit of KGP indicated that these enzymes are synthesized by the strains studied and exist as multiple molecular mass species. The major forms of RGP were identified as 110-, 95-, 70- to 90-, and 50-kDa proteins, the first two being a complex of the 50-kDa catalytic subunit with hemagglutinins, with or without an added membrane anchorage peptide. The other forms are single-chain enzymes. While the 95- and 50-kDa RGP were found predominantly in culture medium, the 110- and 70- to 90-kDa forms associated with membranous fractions of the bacteria. The predominant form of KGP in all strains was a complex of the 60-kDa catalytic domain with hemagglutinins, and vesicle- and membrane-associated KGP was about 15 kDa larger than the 105-kDa enzyme present in culture media. These data explain the apparent complexity of P. gingivalis proteinases and indicate that in all strains tested there are two identical enzymes, one with arginine-X specificity and the other with lysine-X specificity, which, working in concert, are responsible for the trypsin-like activity associated with this bacterium.

Multilayer culture of periodontal ligament epithelial cells: a model for junctional epithelium

The unique features of junctional epithelium involve lack of keratinization, limited differentiation and a relatively permeable structure. In order to study the relationship between differentiation and permeability of stratified epithelium a model system was developed. Porcine periodontal ligament epithelial cells were cultured on the polycarbonate nucleopore membrane of the Transwell two-compartment culture system. Within 5 days of culture the cells formed a confluent multilayered structure. Subsequently, maturation of the structure and differentiation of surface cells took place. Transmission electron microscopy showed that the cells were arranged into basal and suprabasal layers with sparse desmosomal attachments and wide intercellular spaces resembling the organization of junctional epithelium. The basal cells attached to a subepithelial basal lamina through numerous hemidesmosomes. The cytokeratin profile of the cultured epithelium (K5, 6, 14, 16, 19) resembled that of the cells of junctional epithelium attached to the tooth surface. The older cultures expressed differentiation markers, K4, K13 and involucrin, thereby resembling sulcular epithelium. The epithelial permeability, measured by diffusion of phenol red, radioactive dextran or methionine tracers, and as transepithelial electrical resistance, decreased with the increased cell number and maturation of the cultures. The new model provides an organotypic culture system which allows to control differentiation of a multilayered periodontal epithelium. It thus may serve as a valuable new tool for studies on the permeability and behaviour of periodontal epithelium under the influence of exogenous and endogenous factors.

Proteolytic enzymes as indicators of periodontal health in gingival crevicular fluid of patients with Sjögren's syndrome

The present study characterizes the periodontal status of patients with Sjögren's syndrome (SS) and measures collagenase, elastase and gelatinase in gingival crevicular fluid (GCF) from these patients compared with adult individuals with periodontitis and healthy controls. The periodontal status was assessed by the Gingival Bleeding Index (GBI), the Visible Plaque Index (VPI), and pocket depth. Activity measurements were performed for collagenase with SDS-PAGE/laser densitometry, for elastase spectrophotometrically using a synthetic N-succinyl-Ala-Ala-Val p-nitroanilide peptide substrate, and for gelatinase with zymography. Seven of the 8 patients with SS and xerostomia showed a periodontium comparable to that seen in healthy controls. The GCF collagenase and elastase were significantly lower in patients with SS and in healthy controls than in patients with adult periodontitis. It was noteworthy that the one SS patient with periodontitis had high GCF collagenase and elastase activity. In all study groups multiple forms of gelatinases were present, indicating that they represent constitutively expressed proteinases involved in normal tissue remodeling processes. Our findings suggest that periodontal pockets/GCF form a micromilieu not affected by involvement of glandular tissue and, therefore, patients with SS show, clinically and biochemically, a periodontal status comparable to that seen in healthy controls.

Doxycycline inhibits neutrophil (PMN)-type matrix metalloproteinases in human adult periodontitis gingiva

We previously reported that low-dose doxycycline (DOXY) therapy reduces host-derived collagenase activity in gingival tissue of adult periodontitis (AP) patients. However, it was not clear whether this in vivo effect was direct or indirect. In the present study, inflamed human gingival tissue, obtained from AP patients during periodontal surgery, was extracted and the extracts partially purified by (NH4)2SO4 precipitation. The extracts were then analyzed for collagenase activity using SDS-PAGE/fluorography/laser densitometry, and for gelatinase activity using type I gelatin zymography as well as a new quantitative assay using biotinylated type I gelatin as substrate. DOXY was added to the incubation mixture at a final concentration of 0-1000 microM. The concentration of DOXY required to inhibit 50% of the gingival tissue collagenase (IC50) was found to be 16-18 microM in the presence or absence of 1.2 mM APMA (an optimal organomercurial activator of latent procollagenases); this IC50 for DOXY was similar to that exhibited for collagenase or matrix metalloproteinase (MMP)-8 from polymorphonuclear leukocytes (PMNs) and from gingival crevicular fluid (GCF) of AP patients. Of interest, Porphyromonas gingivalis collagenase was also inhibited by similar DOXY levels (IC50 = 15 microM), however the collagenase activity observed in the gingival tissue extracts was found to be of mammalian not bacterial origin based on the production of the specific alpha A (3/4) and alpha B (1/4) collagen degradation fragments. In contrast, the inhibition of collagenase purified from culture media of human gingival fibroblasts (MMP-1) required much greater DOXY levels (IC50 = 280 microM). The predominant molecular forms of gelatinolytic activity presented in the AP patients gingival tissue extracts were found to closely correspond to the 92 kD PMN-type gelatinase (MMP-9) although small quantities of 72 kD fibroblast-type gelatinase (MMP-2), and some other low molecular weight gelatinases, were also detected. The IC50 of DOXY versus gingival tissue gelatinolytic activity was estimated at 30-50 microM measure using either type I gelatin zymography or the biotinylated type I gelatin assay. We conclude that MMPS in inflamed gingival tissue of AP patients, like those in GCF, originate primarily from infiltrating PMNs rather than resident gingival cells (fibroblasts and epithelial cells) or monocyte/macrophages, and that their pathologically-elevated tissue-degrading activities can be directly inhibited by pharmacologic levels of doxycycline.

Purification and characterization of lysine- and arginine-specific gingivain proteases from Porphyromonas gingivalis

Four gingivain proteases, active in presence of L-cysteine, were purified from spent culture media of oral pathogen Porphyromonas gingivalis by ion-exchange chromatography on MonoQ and chromatofocusing on MonoP columns. Three of the purified proteases, with molecular masses of 75 kDa, 70 kDa and 55 kDa, respectively, hydrolyzed synthetic chromogenic substrates with arginine in the P1 position. One protease, with a molecular mass of 80 kDa, hydrolyzed substrates with lysine in the P1 position. It is proposed these enzymes be named: arg-gingivain-75, arg-gingivain-70, arg-gingivain-55, and lys-gingivain-80, respectively, based on their molecular mass and specificity for either arginine or lysine in the P1 position.

In vivo inhibition of human neutrophil collagenase (MMP-8) activity during long-term combination therapy of doxycycline and non-steroidal anti-inflammatory drugs (NSAID) in acute reactive arthritis

We studied the in vivo effect of long-term doxycycline treatment combined with NSAID on human interstitial collagenases, other matrix metalloproteinases, serine proteinases, tissue inhibitor of matrix metalloproteinase-1 (TIMP-1) and lactoferrin from saliva and serum during the course of acute reactive arthritis (ReA). Collagenase activity and serine proteases (elastase-like, cathepsin G-like and trypsin-like activities) of saliva (n = 10) and gelatinase, lactoferrin and TIMP-1 of saliva (n = 10) and serum (n = 10) samples before and after 2 months doxycycline treatment, combined with NSAID, were studied by quantitative SDS-PAGE assay, ELISA assay and by spectrophotometric assay. The cellular source and molecular forms of salivary collagenase were characterized by immunoblotting using specific antisera. We found that activities of total and endogenously active interstitial collagenase reduced significantly. The salivary collagenase was found to originate from neutrophils. No fragmentation of either pro 75-kD and active 65-kD MMP-8 was detected after 2 months doxycycline treatment. However, during 2 months doxycycline and NSAID treatment no reduction of salivary and serum gelatinase, lactoferrin and TIMP-1-levels and salivary serine protease activities were detected. The in vivo inhibition of collagenase (MMP-8) activity during long-term doxycycline therapy in human saliva containing inflammatory exudate of ReA patients may contribute to the reduced tissue destruction observed in recent clinical and animal model studies in arthritides during long-term doxycycline/tetracycline treatment.

Salivary collagenase, elastase- and trypsin-like proteases as biochemical markers of periodontal tissue destruction in adult and localized juvenile periodontitis

The profile of salivary proteases and their cellular origin, with special reference to polymorphonuclear leukocytes and bacteria, was studied in localized juvenile periodontitis and compared with adult periodontitis and healthy controls. General proteolytic activity in saliva as well as collagenase, elastase-like and trypsin-like activity was measured. In addition, the sensitivity of salivary collagenase of patients with localized juvenile periodontitis to doxycycline inhibition was studied. The saliva of localized juvenile periodontitis patients contained low amounts of collagenase compared with adult periodontitis saliva, and almost all salivary collagenase was found to exist in endogenously active form, as was found to be the case also in adult periodontitis patients and healthy controls. The salivary collagenase of localized juvenile periodontitis patients was relatively insensitive to 100 mumol/l doxycycline but was completely inhibited by 600 mumol/l doxycycline, reflecting rather matrix metalloproteinase-1 (fibroblast-type) than matrix metalloproteinase-8 (polymorphonuclear leukocyte) enzyme. The saliva of localized juvenile periodontitis patients also contained low amounts of elastase-like activity compared with the saliva of untreated adult periodontitis patients. Scaling and root planing caused a significant decrease in elastase-like activity in the saliva of adult periodontitis patients. General proteolytic and trypsin-like activities were also low in the saliva of localized juvenile periodontitis patients. Furthermore, the reducing agent beta-mercaptoethanol did not activate or inhibit the salivary trypsin-like activity of localized juvenile periodontitis or adult periodontitis patients, although the reductant readily activated partially purified Porphyromonas gingivalis trypsin-like protease in a characteristic manner.(ABSTRACT TRUNCATED AT 250 WORDS)

Purification and characterization of a protease from Porphyromonas gingivalis capable of degrading salt-solubilized collagen

An enzyme capable of hydrolyzing the substrate 4-phenylazobenzyloxycarbonyl-L-prolyl-leucyl-glycyl-prolyl-D-ar gin ine (pZ-peptide), pZ-peptidase, was purified from the oral bacterium Porphyromonas gingivalis. pZ-peptidase hydrolyzed salt-solubilized type I collagen from rat skin, rat plasma low-molecular-weight kininogen, and transferrin at room temperature in the presence of calcium and dithiothreitol. pZ-peptidase did not cleave acid-soluble type I calf skin collagen, type V placental collagen, lysozyme, albumin, or human plasma fibrinogen. Furthermore, the purified enzyme did not hydrolyze N-alpha-benzoyl-DL-Arg-p-nitroanilide, Gly-Pro-p-nitroanilide, N-p-tosyl-Gly-Pro-Arg-p-nitroanilide, N-p-tosyl-Gly-Pro-Lys-p-nitroanilide, azoalbumin, or azocasein. Under reducing conditions, the native enzyme migrated as a single band at 120 kDa on sodium dodecyl sulfate (SDS)-polyacrylamide gel electrophoresis. However, when heated to 100 degrees C for 10 min in SDS under reducing conditions, the enzyme migrated as a major band at 50 kDa and a minor band at 60 kDa on SDS-polyacrylamide gel electrophoresis. Zymography using calf skin gelatin revealed the gelatin-cleaving activity of the enzyme as evidenced by a diffuse band in the range of 120 to 300 kDa under reducing conditions at room temperature, suggesting that this is the native form of the enzyme. However, incubation at 50 degrees C for 10 min under reducing conditions showed gelatin-cleaving activity at a distinct band of 60 kDa. A minimum temperature of 50 degrees C was required to dissociate the 60-kDa chain from the native complex in active form on gelatin zymography. The ability of the enzyme to cleave other proteins, including kininogen and transferrin, suggests that it has specificity for the Pro-X-Gly sequence found in several proteins, including collagen.

Isolation and characterization of the Porphyromonas gingivalis prtT gene, coding for protease activity

The prtT gene, coding for trypsinlike proteolytic activity, has been isolated from Porphyromonas gingivalis ATCC 53977. This gene is present immediately downstream from the sod gene on a 5.9-kb DNA fragment from the organism isolated in Escherichia coli. The complete nucleotide sequence of the gene was determined, and the deduced amino acid sequence of the enzyme corresponds to a 53.9-kDa protein with an estimated pI of 11.85. Gelatin-sodium dodecyl sulfate-polyacrylamide gel electrophoresis zymography also indicated a similar molecular size for the protease. The enzyme was purified to near homogeneity following anion-exchange and gel-filtration chromatography. The purified enzyme also exhibited a single protein species with a size of approximately 53 kDa. Enzyme activity was strongly dependent upon the presence of reducing agents (dithiothreitol, cysteine, and 2-mercaptoethanol) and was also stimulated in the presence of calcium ions. A comparison of the properties of the prtT gene product with comparable parameters of proteases previously purified from different strains of P. gingivalis suggested that the cloned protease represents a previously uncharacterized enzyme.

Expression of Porphyromonas gingivalis proteolytic activity in Escherichia coli

Porphyromonas gingivalis (formerly Bacteroides gingivalis) degrades numerous protein substrates including collagen, fibrinogen, fibronectin, gelatin, casein, immunoglobulins and complement components. In order to clone one or more of these protease genes, a genomic library was constructed with Sau3A1 restriction fragments of chromosomal DNA from P. gingivalis ATCC 33277 ligated into the temperature-regulated vector pCQV2, and expressed in Escherichia coli DH5 alpha mcr. The electro-transformants (3 x 10(4)) were screened for general protease activity on Luria broth agar containing ampicillin (50 mg/l) and sodium caseinate (2%). One casein-hydrolyzing clone was detected and subcultured, and the activity of the cell extracts was characterized. We were able to show that the protease-positive clone, (pTEM1), had broad substrate specificity. Colorimetric assays indicated the hydrolysis of azocoll, azocasein, collagen, elastin-congo red and artificial substrates. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis was used to confirm that collagen, casein, fibrinogen and fibronectin were degraded by the clone.

Identification of proteases from periodontopathogenic bacteria as activators of latent human neutrophil and fibroblast-type interstitial collagenases

Activation of latent human fibroblast-type and neutrophil interstitial procollagenases as well as degradation of native type I collagen by supra- and subgingival dental plaque extracts, an 80-kDa trypsinlike protease from Porphyromas gingivalis (ATCC 33277), a 95-kDa chymotrypsinlike protease from Treponema denticola (ATCC 29522), and selected bacterial species commonly isolated in periodontitis was studied. The bacteria included were Prevotella intermedia (ATCC 25261), Prevotella buccae (ES 57), Prevotella oris (ATCC 33573), Porphyromonas endodontalis (ES 54b), Actinobacillus actinomycetemcomitans (ATCC 295222), Fusobacterium nucleatum (ATCC 10953), Mitsuokella dentalis (DSM 3688), and Streptococcus mitis (ATCC 15909). None of the bacteria activated latent procollagenases; however, both sub- and supragingival dental plaque extracts (neutral salt extraction) and proteases isolated from cell extracts from potentially periodontopathogenic bacteria P. gingivalis and T. denticola were found to activate latent human fibroblast-type and neutrophil interstitial procollagenases. The fibroblast-type interstitial collagenase was more efficiently activated by bacterial proteases than the neutrophil counterpart, which instead preferred nonproteolytic activation by the oxidative agent hypochlorous acid. The proteases were not able to convert collagenase tissue inhibitor of metalloproteinase (TIMP-1) complexes into active form or to change the ability of TIMP-1 to inhibit interstitial collagenase. None of the studied bacteria, proteases from P. gingivalis and T. denticola, or extracts of supra- and subgingival dental plaque showed any significant collagenolytic activity. However, the proteases degraded native and denatured collagen fragments after cleavage by interstitial collagenase and gelatinase. Our results indicate that proteases from periodontopathogenic bacteria can act as direct proteolytic activators of human procollagenases and degrade collagen fragments. Thus, in concert with host enzymes the bacterial proteases may participate in periodontal tissue destruction.

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.

Inhibition of Porphyromonas gingivalis adhesion to Streptococcus gordonii by human submandibular-sublingual saliva

Porphyromonas gingivalis W50 adheres in vitro to biofilms of Streptococcus gordonii G9B. This phenomenon is believed to facilitate the initial colonization of the oral cavity by P. gingivalis and to contribute to the maturation of dental plaque. In this report, we describe the modulating effects of human submandibular-sublingual saliva (HSMSL) on this in vitro model of intergeneric bacterial adhesion (coaggregation). HSMSL inhibited P. gingivalis adhesion to S. gordonii by 50% at a concentration of 57 micrograms of protein per ml. Maximum inhibitory activity was associated with a 43-kDa protein obtained by sequential Sephadex G200 gel filtration and CM52 ion-exchange chromatography of HSMSL. Pools of other column fractions of HSMSL showed no effect or were slightly stimulatory for bacterial adhesion. The binding of radioiodinated column fractions containing the 43-kDa protein by P. gingivalis was accompanied by their rapid enzymatic degradation. Treating P. gingivalis at 60 degrees C for 30 min or with protease inhibitors (phenylmethylsulfonyl fluoride and sodium iodoacetate) reduced adherence to streptococcal biofilms. These treatments did not prevent P. gingivalis from binding soluble HSMSL saliva components, although subsequent proteolysis was nearly eliminated. These observations indicate that surface-associated proteases of P. gingivalis, either independently or in concert with adjacent surface adhesins, interact with surfaces of oral streptococci to facilitate interbacterial adhesion. The adhesion-blocking properties of HSMSL, particularly the 43-kDa protein, may represent an important host defense mechanism in the oral cavity.