Isolation and characterization of protease from culture supernatant of Bacteroides gingivalis

Porphyromonas gingivalis is a Strong Risk Factor for Alzheimer's Disease

Porphyromonas gingivalis (P. gingivalis) is one of the several important bacterial pathogens associated with the sporadic Alzheimer’s disease (AD). Different serotypes are either capsulated or are non-capsulated. It has been demonstrated that P. gingivalis (non-capsulated) can reproduce the neurodegenerative AD-like changes in vitro, and a capsular P. gingivalis (strain W83) could reproduce the cardinal hallmark lesions of AD in a wild-type mouse model. All P. gingivalis forms express proteolytically active proteases that enable cleavage of the amyloid-β protin precursor (AβPP) and tau resulting in the formation of amyloid-β and neurofibrillary tangles. Tau is an established substrate for gingipains, which can cleave tau into various peptides. Some of the P. gingivalis fragmented tau protein peptides contain “VQIINK” and “VQIVYK” hexapeptide motifs which map to the flanking regions of the microtubule binding domains and are also found in paired helical filaments that form NFTs. P. gingivalis can induce peripheral inflammation in periodontitis and can also initiate signaling pathways that activate kinases, which in turn, phosphorylate neuronal tau. Periodontal disease related inflammation has metabolic implications for an individual’s peripheral and brain health as patients suffering from generalized periodontitis often have related co-morbidities and are “at risk” of developing AD. The aim here is to discuss the role of P. gingivalis behind such associations with the backdrop of huge efforts to test P. gingivalis virulence factors clinically (GAIN Trial: Phase 2/3 Study of COR388 in Subjects with AD) with inhibitors, which may lead to an intervention by reducing the pathogenic bacterial load.

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.

Gingipain RgpB is excreted as a proenzyme in the vimA-defective mutant Porphyromonas gingivalis FLL92

We have previously shown that the unique vimA (virulence-modulating) gene could modulate proteolytic activity in Porphyromomas gingivalis. Although a reduction in cysteine protease activity was observed in the vimA-defective mutant, P. gingivalis FLL92, compared to that of the wild-type strain, no changes were seen in the expression of the gingipain genes. This result might suggest posttranscriptional regulation of protease expression. To determine whether there was a defect in the translation, transport, or maturation of the gingipains, P. gingivalis FLL92 was further characterized. In contrast to the wild-type strain, a 90% reduction was seen in both Rgp and Kgp protease activities in strain FLL92 during the exponential growth phase. These activities, however, increased to approximately 60% of that of the wild-type strain during stationary phase. Throughout all the growth phases, Rgp and Kgp activities were mostly soluble, in contrast to those of the wild-type strain. Western blot analyses identified unique Rgp- and Kgp-immunoreactive bands in extracellular protein fractions from FLL92 grown to late exponential phase. Also, the RgpB proenzyme was identified in this fraction by mass spectrometry. In addition, in vitro protease activity could be induced by a urea denaturation-renaturation cycle in this fraction. These results indicate that protease activity in P. gingivalis may be growth phase regulated, possibly by multiple mechanisms. Furthermore, the gingipain RgpB is excreted in an inactive form in the vimA mutant. In addition, these results provide the first evidence of posttranslational regulation of protease activity in P. gingivalis and may suggest an important role for the vimA gene in protease activation in this organism.

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.

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.

Porphyromonas gingivalis proteinases as virulence factors in the development of periodontitis

Porphyromonas gingivalis contains exceedingly high concentrations of cysteine proteinases with trypsin-like activity which have been implicated as virulence factors in adult-onset periodontitis. These enzymes, referred to as gingipains, cleave protein and peptide substrates after arginine (gingipain R) and lysine residues (gingipain K), and it has been found that neither is easily inhibited by host proteinase inhibitors. Examination of the properties of each proteinase clearly indicates a role(s) for both in the dysregulation of a number of normally tightly controlled pathways. The effects of such uncontrolled proteolysis are the development of edema (kallikrein/kinin pathway activation by gingipain R), neutrophil infiltration (complement pathway activation by gingipain R), and bleeding (degradation of fibrinogen by gingipain K). Since three of the major hallmarks of periodontitis involve increased crevicular flow, neutrophil accumulation at infected sites and bleeding on probing, it seems likely that both P. gingivalis-derived proteinases are important virulence factors in the development of periodontal disease.

The potential role of alpha 2-macroglobulin in the control of cysteine proteinases (gingipains) from Porphyromonas gingivalis

Porphyromonas gingivalis is closely associated with the development of some forms of periodontitis. The major cysteine proteinases released by this bacterium hydrolyze peptide bonds only after arginyl (gingipain R) or lysyl residues (gingipain K). No target protein inhibitors have been identified for either enzyme, leading us to investigate their inhibition by human plasma alpha 2-macroglobulin (alpha 2M). Both 50- and 95 kDa gingipain R were efficiently inhibited by alpha 2M, whereas the catalytic activity of gingipain K could not be eliminated. All 3 enzymes were, however, inhibited by a homologous macroglobulin from rat plasma, alpha 1-inhibitor-3 (alpha 1I3). alpha-Macroglobulins must be cleaved in the so-called "bait region" in order to inhibit proteinases by a mechanism involving physical entrapment of the enzyme. A comparison of the amino acid sequences of the 2 macroglobulins indicates that the lack of lysyl residues within the bait region of alpha 2M protects Lys-specific proteinases from being trapped. On this basis, other highly specific proteinases might also not be inhibited by alpha 2M, possibly explaining the inability of the inhibitor to control proteolytic activity in some bacterially induced inflammatory states, despite its abundance (2-5 mg/ml) in vascular fluids.

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.

Effect of periodontal treatment on the protein composition of whole and parotid saliva

Cystatins are physiological inhibitors of cysteine proteinases and widely distributed in human tissues and fluids including saliva. Cystatins S, SA, SN, and D are only found in glandular saliva and tear fluid whereas cystatin C has been detected in all tested biological fluids. Previous studies demonstrated that total cystatin activity and cystatin C concentration were highest in whole and parotid saliva of periodontitis patients compared to healthy subjects suggesting a response of the salivary glands to an inflammatory condition of the oral cavity. Based on these results we studied a possible change in the concentration of cystatin S, cystatin C, albumin, IgA, amylase activity, and cystatin activity in a whole and parotid saliva of 20 periodontitis patients as a consequence of periodontal treatment. Saliva samples were quantified for cystatins S and C, albumin, and IgA by enzyme-linked immunosorbent assay. Amylase was determined in an activity assay and total cystatin activity was measured towards pa-pain. The clinical condition of the subjects improved significantly after 6 months of periodontal therapy whereas biochemical analyses of whole and parotid saliva indicated that significant changes in salivary protein composition occurred only in whole saliva. Total cystatin activity (P < 0.05) and cystatin C concentration (P < 0.05) of whole saliva samples collected after periodontal treatment decreased to normal healthy control values. Further, concentrations of cystatin S were unchanged during the periodontal treatment process. These results suggest that other sources of cystatins than the parotid gland i.e.; other salivary glands or crevicular fluid, are involved in the decrease of total cystatin activity in whole saliva after periodontal treatment.

Protein composition of whole and parotid saliva in healthy and periodontitis subjects. Determination of cystatins, albumin, amylase and IgA

Cystatins are physiological inhibitors of cysteine proteinases and they are widely distributed in human tissues and body fluids including saliva. We previously reported an increased cystatin activity in whole saliva of gingivitis and periodontitis subjects. Based on this result we decided to investigate the type and origin of cystatins involved in this increased cystatin activity by collecting both whole and parotid saliva of 25 healthy and 30 periodontitis subjects. Saliva samples were quantified for cystatins S and C by enzyme-linked immunosorbent assay and cystatin activities were measured toward papain. Besides, three other salivary proteins were determined: the plasma protein albumin, the typical parotid derived amylase and the salivary immunoglobulin IgA. The present investigation shows that levels of total protein and cystatin activity as well as the levels of glandular derived proteins amylase and cystatin C were significantly higher in whole and parotid saliva of subjects with periodontitis than in healthy controls. Cystatin S, the major salivary cystatin, however was higher in the whole saliva of the healthy group. Whole saliva concentrations of albumin and IgA, originating from sources other than the glandular cells, were not different between healthy and periodontitis subjects and were also not correlated with the typical salivary gland proteins. In conclusion, this study provides additional evidence that the human salivary glands may respond to an inflammatory disease of the oral cavity, periodontitis, by enhanced synthesis of some acinar proteins.

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.

Delmopinol interactions with cell walls of gram-negative and gram-positive oral bacteria

The main purpose of the present study was to investigate the influence of delmopinol hydrochloride on the cell surface morphology of gram-negative and gram-positive bacterial cells by using transmission electron microscopy. A second purpose was to evaluate the extraction of cell wall material caused by delmopinol and the binding of radiolabelled delmopinol to the various strains. Fresh isolates and type strains of gram-negative rods associated with periodontal disease, Porphyromonas gingivalis, Prevotella intermedia, Actinobacillus actinomycetemcomitans, and strains of the gram-positive streptococci Streptococcus sanguis, Streptococcus mutans and Streptococcus salivarius, were exposed to 3.2 mM (0.1%) or 6.4 mM (0.2%) delmopinol hydrochloride from 1 to 90 min. For electron microscopy the cells were fixed and negatively contrast-stained. Treatment with 6.4 mM delmopinol for 1 min resulted in marked ultrastructural changes of cell wall components and the outer cell membrane of the 3 gram-negative species compared with control cells, whereas the gram-positive streptococci treated with delmopinol showed little or no morphologic alteration as compared with untreated cells. The result from the electron microscopy was confirmed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis of proteins released from bacterial cells treated as for electron microscopy. More material was extracted from the gram-negative rods than from the gram-positive cocci. Significantly more delmopinol bound to the gram-negative rods than to the streptococci. It appears that the amphiphilic properties of delmopinol make gram-negative rods more vulnerable to delmopinol than gram-positive streptococci.

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.

Purification and characterization of two forms of a high-molecular-weight cysteine proteinase (porphypain) from Porphyromonas gingivalis

Porphyromonas gingivalis, and organism implicated in the etiology and pathogenesis of human periodontal diseases, produces a variety of potent proteolytic enzymes, and it has been suggested that these enzymes play a direct role in the destruction of periodontal tissues. We now report that two cell-associated cysteine proteinases of P. gingivalis W12, with molecular masses of approximately 150 kDa (porphypain-1) and 120 kDa (porphypain-2), as determined by sodium dodecyl sulfate (SDS)-polyacrylamide gel electrophoresis, have been separated and purified to apparent homogeneity. These proteinases appear to be SDS-stable conformational variants of a 180-kDa enzyme, and they are the largest cysteine proteinases yet purified from P. gingivalis. The purified proteinases hydrolyze fibrinogen, tosyl-Gly-L-Pro-L-Arg p-nitroanilide, and tosyl-Gly-L-Pro-L-Lys p-nitroanilide. While hydrolysis of both synthetic substrates by porphypain-1 and -2 requires activation by reducing agents, is inhibited by EDTA, and is stimulated in the presence of derivatives of glycine, the Arg-amidolytic activity is sensitive to leupeptin and H-D-tyrosyl-L-prolyl-L-arginyl chloromethyl ketone, whereas the Lys-amidolytic activity is sensitive to tosyl-L-lysyl chloromethyl ketone and insensitive to leupeptin. These data suggest that porphypains contain two types of active sites. These cell-associated P. gingivalis proteinases may contribute significantly and directly to periodontal tissue destruction.

Participation of an arginyl residue of insulin chain B in the inhibition of hemagglutination by Porphyromonas gingivalis

Insulin chain B, containing each one arginyl and lysyl residue in its peptide chain, inhibited hemagglutination by Porphyromonas gingivalis. To determine the further inhibitory profile, chain B was digested into 4 fragments by protease, which was contained in the preparation of hemagglutinin from P. gingivalis. Identification of each fragment by the amino acid analysis revealed that the chain was cleaved at the carboxyl site of arginyl and/or lysyl residues, but one fragment contained citrulline instead of arginine at its carboxyl terminal. This citrulline might have originated from arginine by an arginine deiminase-like enzyme of P. gingivalis. Only one fragment that contained the arginyl residue exhibited inhibitory activity on hemagglutination, but it was considerably weakened compared with that of the intact chain B. The difference in the inhibitory activity seemed to depend on the position of an arginyl residue in the peptide; this was also confirmed using several derivatives of bradykinin. The present result suggests that the internal arginyl residue in a peptide chain may be critical for the inhibition of the hemagglutination by P. gingivalis.

Vascular permeability enhancing activity of Porphyromonas gingivalis protease in guinea pigs

Porphyromonas gingivalis protease, which had been isolated from a culture supernatant, caused vascular permeability enhancement in a dose-dependent manner when injected into guinea pig skin. The permeability-enhancing reaction caused by the protease was not affected by treatment with antihistamine, but was greatly augmented by simultaneous injection of a kinin potentiator, carboxypeptidase N inhibitor. However, the reaction was inhibited by soybean trypsin inhibitor or alpha 2-antiplasmin, although both of these inhibitors could not inhibit P. gingivalis protease at all by themselves. A bradykinin-degrading enzyme, carboxypeptidase B, weakened this vascular reaction. Results described indicate that the permeability-enhancing reaction induced by the protease is caused by activation, of the kallikrein-kinin cascade in the tissue.

Cytotoxicity of Porphyromonas gingivalis toward cultured human gingival fibroblasts

Direct cytotoxicity of black-pigmented anaerobic rods was studied on the confluent monolayer of human gingival fibroblasts in vitro. Only strains of Porphyromonas gingivalis caused morphological alteration (cell-rounding) and notable depression of viability of fibroblasts. To determine the location of the cytotoxicity, bacterial surface components, i.e., outer membrane, lipopolysaccharide, fimbriae and outer membrane vesicles were prepared from P. gingivalis and their cytotoxicity was assessed. Among these preparations, only outer membrane vesicles are supposed to have high affinity to human gingival fibroblasts, and the cytotoxicity of outer membrane vesicles was found to be much stronger than that of the other constituents. This cytotoxic factor seemed to consist largely of protein and to be associated with the enzyme activity of outer membrane vesicles. The effects of some protease inhibitors and L-cysteine on the cytotoxicity of outer membrane vesicles suggest that the mechanism of cell-rounding is different from that of cell death.

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.

Protein, albumin and cystatin concentrations in saliva of healthy subjects and of patients with gingivitis or periodontitis

Salivary protein, albumin and cystatin concentrations were investigated in subjects with a healthy periodontium and in patients with gingivitis or periodontitis. Protein and albumin concentrations in saliva of individuals with gingivitis or periodontitis were significantly increased compared with healthy subjects. Salivary protein and albumin appeared to be positively correlated in all the groups, which suggests that the increase in salivary protein concentration in subjects with gingivitis or periodontitis is caused by leakage of plasma proteins. Cystatin concentrations in saliva of subjects with periodontitis were significantly increased when compared with the healthy group and the gingivitis group (p < 0.01). In the gingivitis and periodontitis group, salivary cystatin was only weakly correlated with albumin concentrations, which suggests that the increased salivary cystatin activity found in subjects with gingivitis and periodontitis is derived from sources other than plasma.

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.

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 three types of proteases from culture supernatants of Porphyromonas gingivalis

Three types of caseinolytic proteases (Pase-A, Pase-B, and Pase-C) were isolated and purified from culture supernatants of Porphyromonas gingivalis 381 by the combined procedures of acetone precipitation, gel filtration, solubilization with octylthioglucoside followed by affinity chromatography on arginine-Sepharose 4B, high-performance liquid chromatography (HPLC) on Biofine IEC-DEAE, and HPLC on TSK-G4000SW. By sodium dodecyl sulfate-polyacrylamide gel electrophoresis, Pase-A and -B showed diffuse protein bands of 105 to 110 and 72 to 80 kDa, respectively, and Pase-C showed a clear band of about 44 kDa. Pase-B and -C hydrolyzed some synthetic substrates for trypsin, but Pase-B did not act on the carboxyl side of lysine in insulin chain B or on a synthetic substrate which trypsin and Pase-C acted on. Pase-A did not act on the synthetic substrates but cleaved the peptide bonds Glu-Ala and Ala-Leu of insulin. Leupeptin inhibition of the caseinolytic activity of both Pase-A and -B was similar to its inhibition of Pase-C. Phenylmethylsulfonyl fluoride and diisopropyl fluorophosphate strongly inhibited Pase-A, but no significant effect on the other enzymes was observed, suggesting that only Pase-A is a serine protease. The inhibitory characteristics of Pase-B and -C were very similar. Pase-A was not thiol dependent for enzyme activity, but Pase-B was strongly dependent, i.e., even more so than Pase-C. Pase-A inactivated the inhibitory activity of plasma alpha-1-antitrypsin, but the other two did not. These results show that P. gingivalis produces different types of proteases other than the trypsinlike protease generally reported.

Periodontal bone level and gingival proteinase activity in gnotobiotic rats immunized with Bacteroides gingivalis

Bacteroides gingivalis is associated with various forms of periodontal disease. To assess the role of the immune response in modulating B. gingivalis-associated periodontal disease, the effect of immunization of B. gingivalis-induced periodontal bone loss was evaluated in gnotobiotic rats. Male Sprague-Dawley rats immunized with various doses of whole cells or sham-immunized with incomplete Freund's adjuvant were monoinfected with B. gingivalis in carboxymethylcellulose by gavage. Two additional groups served as either sham-immunized or untreated germ-free controls. Forty-two days after infection, all rats were killed, periodontal bone level was assessed morphometrically and radiographically, and gingival proteinase (mammalian collagenase and acid cathepsin) activity was assessed biochemically. B. gingivalis was present in oral samples from all monoinfected rats, and no contaminating bacteria were detected in any oral or fecal sample. Animals immunized with B. gingivalis cells had elevated serum and saliva antibodies to whole cells and partially purified fimbriae from B. gingivalis. Infected sham-immunized rats had significantly more periodontal bone loss than noninfected controls, whereas the periodontal bone level in infected rats immunized with 10(10) B. gingivalis cells was similar to that of the noninfected controls. The activities of gingival collagenase and cathepsin B and L were high in sham-immunized infected rats and low in all other animal groups. In conclusion, it is possible to reduce B. gingivalis-induced periodontal tissue loss in gnotobiotic rats by immunization.

Extracellular vesicle-associated and soluble trypsin-like enzyme fractions of Porphyromonas gingivalis W50

Soluble vesicle-associated trypsin-like enzyme fractions (VSF) were prepared by sonication from extracellular vesicles (ECV) from strains W50 and W50/BE1. High-(H), intermediate-(I) and low-(L) molecular-weight VSF enzyme subfractions were identified by non-dissociative gel filtration chromatography with Mr 160, 95 and 60 kDa respectively. The chromatographic profiles of W50 VSF from 48-h and 72-h cultures were identical. W50/BE1 VSF displayed a higher ratio of the 160 to 60 kDa components. This ratio was reduced in VSF from 72-h cultures. Extracellular soluble protein (EP) trypsin profiles were similar to their respective VSF, but the 60 kDa component predominated. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) revealed a loss of soluble extracellular polypeptides with culture age. A polyclonal antiserum to EP subfraction L reacted in immunoblots with a 50 kDa peptide of subfraction L of W50. Whole EP and its subfraction H displayed a 50 kDa immunoreactive peptide but no peptides of higher molecular weight. This antiserum reacted with a similar sized peptide, and with lower-molecular-weight components in whole ECV. Gelatin substrate zymography of whole EP following non-reducing SDS-PAGE revealed a major 80 kDa protease that increased with culture age. Minor protease bands of 70 and 50 kDa were also detected.

Serological studies of Porphyromonas (Bacteroides) gingivalis and correlation with enzyme activity

Porphyromonas gingivalis from the human oral cavity was serologically characterized using absorbed and unabsorbed rabbit antisera. The reference strains were ATCC 33277, W50, W83, 381 and hara 1. The 432 isolates were from periodontal pockets of 63 patients with adult periodontitis. Using sonicated antigens, four serotypes were identified by immunodiffusion tests and immunoelectrophoresis. Each patient harbored only one serotype of P. gingivalis, and serotypes I and IV predominated. The incidence of serotype I was four times higher than that of serotype II, and approximately seven times higher than that of serotype III. The collagenolytic and some proteolytic enzymes of representatives of each serotype were assessed. Although all strains produced these enzymes to some degree, some differences in their levels were observed. Serotype II strains were more collagenolytic than serotypes I or III, and serotype III exhibited lower activities of N-CBz-glycyl-glycyl-arginyl peptidase than other serotypes. Antibiotic sensitivity was also compared with antimicrobial disks, and serotype IV strains exhibited high sensitivity to the four antibiotics used.

Specific cell components of Bacteroides gingivalis mediate binding and degradation of human fibrinogen

Bacteroides (Porphyromonas) gingivalis, which has been implicated as an etiologic agent in human periodontal diseases, has been shown to bind and degrade human fibrinogen. B. gingivalis strains bind fibrinogen reversibly and with high affinity and bind to a specific region of the fibrinogen molecule that appears to be located between the D and E domains (M. S. Lantz, R. D. Allen, P. Bounelis, L. M. Switalski, and M. Hook, J. Bacteriol. 172:716-726, 1990). We now report that human fibrinogen is bound and then degraded by specific B. gingivalis components that appear to be localized at the cell surface. Fibrinogen binding to bacterial cells occurred at 4, 22, and 37 degrees C. A functional fibrinogen-binding component (Mr, 150,000) was identified when sodium dodecyl sulfate-solubilized bacteria were fractionated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, transferred to nitrocellulose membranes, and probed with 125I-fibrinogen. Fibrinogen degradation did not occur at 4 degrees C but did occur at 22 and 37 degrees C. When bacteria and iodinated fibrinogen were incubated at 37 degrees C, two major fibrinogen fragments (Mr, 97,000 and 50,000) accumulated in incubation mixture supernatant fractions. Two major fibrinogen-degrading components (Mr, 120,000 and 150,000) have been identified by sodium dodecyl sulfate-polyacrylamide gel electrophoresis in substrate-containing gels. Fibrinogen degradation by the Mr-120,000 and -150,000 proteases was enhanced by reducing agents, completely inhibited by N-alpha-p-tosyl-L-lysyl chloromethyl ketone, and partially inhibited by n-ethyl maleimide, suggesting that these enzymes are thiol-dependent proteases with trypsinlike substrate specificity. The fibrinogen-binding component could be separated from the fibrinogen-degrading components by selective solubilization of bacteria in sodium deoxycholate.

Black-pigmented, asaccharolytic Bacteroides species resembling Porphyromonas gingivalis (Bacteroides gingivalis) from beagle dogs

Black-pigmented, asaccharolytic Bacteroides strains, which positively reacted with anti-Bacteroides gingivalis (now reclassified as Porphyromonas gingivalis) serum, were isolated from beagle dogs, and their characteristics were studied and compared with those of P. gingivalis. The strains from dogs were different from P. gingivalis in their catalase activity, nutritional requirements and oxygen tolerance, and double-immunodiffusion tests showed serological dissimilarity between the strains from dogs and P. gingivalis. However, the strains from dogs had guanine-plus-cytosine contents of 49.0 to 49.3 mol %, which were very similar to P. gingivalis, and they showed strong DNA-DNA hybridization with P. gingivalis. These results indicated that beagle dogs had Porphyromonas species analogous to P. gingivalis in their oral cavities.

Detection of cathepsin B- and L-, elastase-, tryptase-, trypsin-, and dipeptidyl peptidase IV-like activities in crevicular fluid from gingivitis and periodontitis patients with peptidyl derivatives of 7-amino-4-trifluoromethyl coumarin

Crevicular fluid samples were collected from 20 gingivitis and periodontitis patients using filter paper strips; these were then eluted into buffer. Portions of each sample were combined and the activities of this pooled eluate against different peptidyl derivatives of 7-amino-4-trifluoromethyl coumarin (AFC) were examined with respect to their pH profiles and effector responses. Ca-thepsin B- and L-like activity was detected with Bz-Val-Lys-Lys-Arg-AFC; elastase-like activity with MeOSuc-Ala-Ala-Pro-Val-AFC; tryptase-like activity with Z-Ala-Ala-Lys-AFC; trypsin-like activity with Z-Gly-Gly-Arg-AFC; and dipeptidyl peptidase (DPP) IV-like activity with Ala-Pro-AFC. The selectivity and sensitivity of these assays were improved by choice of appropriate conditions. The cathepsin B- and L-, elastase-, tryptase-, and trypsin-like activities all had properties consistent with those from host sources, whilst partial inactivation of the DPP IV-like activity by heat treatment (60 degrees C for 30 min) suggested that it may have represented a mixture of human and Bacteroides gingivalis enzymes. Individual patient eluates showed wide variations in enzyme concentrations, but generally elastase-like activity was by far the highest. The sensitivity of the assays with AFC-linked substrates was such that it should prove possible to measure all five different types of activity in crevicular fluid samples from local periodontal disease sites.

Proteolytic activity in black-pigmented bacteroides species

Black-pigmented Bacteroides species are frequently found in dentoalveolar abscesses. One general mechanism of bacterial virulence is the production of extracellular enzymes which degrade connective tissue or molecules associated with host defense. In this study the proteolytic activity of 18 bacterial strains from 9 black-pigmented Bacteroides species was examined. Bacteroides gingivalis degraded the greatest number of substrates studied and produced the highest levels of enzymatic activity. B. gingivalis was the only species that degraded collagen and produced high levels of enzymes that degraded N-benzoyl-DL-arginine (BANA) and N-CBz-glycyl-glycyl-arginine. Bacteroides intermedius degraded several substrates including PZ peptide. Bacteroides endodontalis produced enzymes that degraded beta-naphthylamide derivatives of glycylproline and glycylphenylalanine. There were considerable differences in enzyme production between strains of the same species. Such heterogeneity between strains in the production of proteolytic enzymes may be relevant to the in vivo infections produced in the host.

Purification of an 80,000-Mr glycylprolyl peptidase from Bacteroides gingivalis

An enzyme from Bacteroides gingivalis SUNYAB A7A1-28 that hydrolyzes the synthetic peptide glycyl-L-proline 4-methoxy-beta-naphthylamide was purified 1,040-fold by urea extraction, gel filtration, ion-exchange chromatography, and fast protein liquid chromatography. The molecular weight of the enzyme was 80,000 as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and 75,000 as determined by gel filtration. The optimum pH for the hydrolysis of glycyl-L-proline 4-methoxy-beta-naphthylamide was 7.5 to 8.5. The enzyme activity was inhibited by the serine protease inhibitors diisopropyl fluorophosphate and phenylmethylsulfonyl fluoride by 82.5 and 78%, respectively. The activity was also inhibited by Hg2+ (55.6%) and Zn2+ (45%).

Heterogeneity of virulence among strains of Bacteroides gingivalis

The ability of fresh isolates of B. gingivalis to establish abscesses in the mouse model was studied by comparing them with established laboratory strains of B. gingivalis. Eight fresh isolates obtained from plaque associated with periodontal disease and grown under similar conditions as established strains were injected subcutaneously on the back of the mouse. All of these strains produced secondary lesions on the abdomen. Septicemia was associated with seven of the strains. Two commonly used laboratory strains, W50 and W83, also produced secondary lesions and septicemia. Five other laboratory strains produced only localized abscesses. On histologic examination, the strains that produced disseminated disease showed invasion of connective disease by individual bacteria that were not in clumps. The strains that produced localized abscesses were characterized by growing in colonies or clumps in the abscess cavity. Four synthetic enzyme substrates were examined to determine whether the differences between invasive and non-invasive strains were due to differences in proteolytic enzyme production. No differences in enzyme production could be demonstrated with the selected substrates.

Cleavage action of a trypsin-like protease from Bacteroides gingivalis 381 on reduced egg-white lysozyme

Soluble reduced lysozyme was extensively digested by a trypsin-like protease purified from the culture supernatant of the bacterium. The digestion peptides were separated and purified by reversed-phase high-performance liquid chromatography, and were subjected to amino acid analysis. The fragments were identified by their amino acid composition, and the cleavage sites in the lysozyme chain were determined. Like mammalian trypsin, the enzyme from B. gingivalis split peptide bonds non-specifically at carboxyl sides of internal arginine and lysine residues, but the lysine present at the amino terminus of the lysozyme chain was not released. In addition, the enzyme cleaved the peptide linkage at the amino side of lysine and bonds between leucine-glycine, alanine-leucine and leucine-serine. Thus the trypsin-like protease from B. gingivalis has some cleavage actions on lysozyme different from those of mammalian trypsin.

Degradation of human secretory immunoglobulin A by protease isolated from the anaerobic periodontopathogenic bacterium, Bacteroides gingivalis

This bacterium is implicated in periodontal diseases of human adult type. Secretory immunoglobulin A (IgA) purified from human colostrum (HC-IgA) was incubated with Bacteroides gingivalis cells or protease isolated from the culture supernatant of B. gingivalis; the digestion of IgA was determined by immunoelectrophoresis and sodium dodecyl sulphate-polyacrylamide gel electrophoresis. B. gingivalis cells almost completely degraded HC-IgA; protease isolated from the culture supernatant cleaved both HC-IgA and secretory IgA in human parotid saliva. Thus by degradation of IgA, the protease may mediate in part the periodontopathogenic role of B. gingivalis by decreasing the oral defence mechanism.