Isolation and characterization of proteases from Bacteroides melaninogenicus

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 a 43-kDa protease of Bacteroides gingivalis

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

Multiple forms of proteases of Bacteroides gingivalis and their cellular location

Protease of Bacteroides gingivalis ATCC 33277 was found in intracellular membrane-free, intracellular membrane-bound and extracellular fractions. The insoluble form of proteases was solubilized with a detergent. The elution patterns of proteases on gel filtration in each fraction were rather different. However, enzymatic properties of the proteases separated by gel filtration were very similar.

The role of Bacteroides gingivalis in periodontal disease

The microbial flora in adult advanced periodontitis lesions is comprised of Gram-negative rods, with Bacteroides gingivalis as one of the major representatives. This review deals with biological properties of surface antigens, hemagglutinin (attachment factor), and capsular structure of B. gingivalis. Sera containing high IgG antibody levels to B. gingivalis enhanced the complement-mediated bactericidal activity in vitro, although the susceptibility to complement-mediated lysis differed among B. gingivalis strains. The protective effect of immunization against B. gingival is infection was examined in hamsters in which cotton threads had been tied to the gingival margins of the mandibular first molar. Repeated oral topical application of hyper-immune sera against B. gingivalis resulted in effective elimination of the organisms from the periodontal lesions in the experimental animals.

Identification of periodontopathic bacteria based upon their peptidase activities

Black-pigmented Bacteroides (BPB) and spirochetes are associated with some forms of periodontal diseases. The enzymes produced by these bacteria may participate in the destruction of gingival and periodontal tissues. Certain proteases and peptidases are unique to Bacteroides gingivalis and Treponema denticola. Our purpose was to study the peptidases of periodontopathogens and to evaluate the use of unique peptidases for detection and identification of these bacteria.

Bacteria used were BPB, Treponema, Fusobacterium, Capnocytophaga, Actinobacillus (Haemophilus), and Eikenella species. Twenty-five substrates, including mono-, di-, and tri-peptides of β-naphthylamide (β-NA) were employed for examination of peptidase activity. Clinically isolated BPB were obtained from 16 adult periodontitis patients. One hundred and ninety-three BPB strains were identified by conventional identification methods, and the peptidase activity was determined with N-Carbobenzoxy-glycyl-glycyl-L-arginine-β-naphthylamide (N-CBz-Gly-Gly-Arg-β-NA) used as a substrate.

Among tested periodontopathic bacteria, only B. gingivalis and T. denticola could strongly hydrolyze some substrates such as N-CBz-Gly-Gly-Arg-β-NA and N-Benzoyl-L-valyl-glycyl-L-arginine-4-methoxy-(3-naphthylamide (Bz-Val-Gly-Arg-β-NA). In subgingival plaque samples, all patients showed BPB, and eight out of 16 patients possessed B. gingivalis by culture. One hundred and ten strains out of 193 BPB isolated were identified as B. gingivalis. Ninety-nine percent of these B. gingivalis strains identified showed N-CBz-Gly-Gly-Arg-β-NAhydrolyzing activity on a newly developed colorimetric plate assay. However, none of the other strains showed this activity in cultures of subgingival plaque which did not allow growth of spirochetes.

Enzymes, such as N-CBz-Gly-Gly-Arg-peptidase and Bz-Val-Gly-Arg-peptidase, specific for B. gingivalis and T. denticola seem to be useful for rapid detection and identification of these bacteria.

Isolation of a membrane-associated Bacteroides gingivalis glycylprolyl protease

A low-molecular-weight proteolytic enzyme was purified 47-fold from outer membranes of Bacteroides gingivalis ATCC 33277 by preparative polyacrylamide gel electrophoresis. The enzyme was present in all B. gingivalis strains tested but was not found in other species of black-pigmented Bacteroides. The molecular weight, determined by sodium dodecyl sulfate (SDS)-polyacrylamide gel electrophoresis, was 19,500 when the enzyme was heated to 100 degrees C in SDS before electrophoresis and 29,000 when it was mixed with SDS but not heated. The optimum pH, with azocasein as the substrate, was between 6.0 and 6.5. The activity was inhibited by phenylmethylsulfonyl fluoride, N-alpha-p-tosyl-L-lysine chloromethyl ketone, Hg2+, and various reducing agents. The enzyme was active against azocasein, azocoll, proline-rich protein from saliva, and the synthetic peptide glycyl-L-proline-p-nitroanilide. The enzyme did not degrade acid-soluble collagen nor did it hydrolyze various arginine- and lysine-containing synthetic substrates.

Purification and characterization of a thiol-protease from Bacteroides gingivalis strain 381

A protease from the culture supernatant of Bacteroides gingivalis 381, which hydrolyzes the chromogenic substrate Na-benzoyl-DL-arginine-p-nitroanilide (BAPNA), was partially purified by ammonium sulfate precipitation, gel filtration, and anion exchange chromatography. The molecular weight of this protease was determined by SDS-PAGE to be ca. 49,000. The optimum pH was around 7.6. The protease was stable at neutral pH and up to 40 degrees C. The isoelectric point was 4.9. The enzyme activity was enhanced by dithiothreitol, L-cysteine, and 2-mercaptoethanol and inhibited by p-chloromercuribenzoic acid, N-ethylmaleimide, and iodoacetic acid.

Purification and characterization of a protease from Bacteroides gingivalis 381

An intracellular membrane-free, trypsinlike protease was isolated from cells of Bacteroides gingivalis 381. The protease was extracted from the cells by ultrasonic treatment and was purified about 250-fold with a recovery of 2% by sequential procedures. The properties of the protease were as follows: its optimal pH was 8.5; its activity was almost completely lost on incubation at 50 degrees C for 15 min; its activity was inhibited by diisopropylfluorophosphate, p-toluenesulfonyl-L-lysine chloromethyl ketone hydrochloride, leupeptin, Mn2+, Cu2+, and Zn2+; it hydrolyzed casein, azocasein, N-alpha-benzoyl-DL-arginine-p-nitroanilide (BAPNA), bovine serum albumin, azocoll, and gelatin, but not N-alpha-benzoyl-DL-lysine-p-nitroanilide or human serum immunoglobulin A; its molecular weight was estimated as 45,000 by gel filtration and 50,000 by sodium dodecyl sulfate-polyacrylamide gel electrophoresis; and its Km values for azocasein and BAPNA were 1.11% and 0.19 mM, respectively.

Functional characterization of extracellular vesicles produced by Bacteroides gingivalis

Extracellular vesicles of Bacteroides gingivalis (type strain 33277) were isolated, and some of their biological activities were characterized. The vesicles were obtained from a 2-day culture after ammonium sulfate precipitation, differential centrifugation, and dialysis. When viewed by electron microscopy, vesicles of approximately 50 nm predominated. The results indicated that the enriched vesicle fraction had a high proteolytic activity against collagen, Azocoll, and N-alpha-benzoyl-DL-arginine p-nitroanilide. The polypeptide pattern of the vesicles was similar but not identical to that of the outer membrane. The membrane vesicles could also promote bacterial adherence between homologous cells as well as mediate attachment between two noncoaggregating bacterial species. These vesicles could thus play an important role in periodontal diseases by serving as a vehicle for toxins and various proteolytic enzymes, as well as being involved in adherence.

Arylaminopeptidase activities of oral bacteria

Protease and peptidase enzymes are thought to play a role in the virulence of many oral organisms, especially those associated with periodontal diseases. In order to evaluate the peptidases of periodontopathogens, we compared the arylaminopeptidase activities of Bacteroides gingivalis with those of other oral and non-oral bacteria. Sixty-three bacterial strains representing the prominent cultivable organisms in human periodontal pockets were tested, including representatives of the black-pigmented Bacteroides, Actinobacillus, Actinomyces, Campylobacter, Capnocytophaga, Eikenella, Fusobacterium, Haemophilus, Lactobacillus, Streptococcus, and Veillonella species. Each micro-organism was examined for its ability to hydrolyze 18 synthetic substrates of beta-naphthylamide derivatives of amino acids, dipeptides, and tripeptides. Quantitation of the enzyme activity was accomplished by colorimetric measurement of the amounts of released beta-naphthylamines. N-CBz-glycyl-glycyl-L-arginine-beta-naphthylamide was readily cleaved by B. gingivalis, but slightly or not at all by the other oral strains tested. L-arginine-beta-naphthylamide was cleaved by B. gingivalis, Capnocytophaga species, and Streptococcus species, but not readily by the other Bacteroides strains. Some dipeptide substrates tested, such as glycyl-L-arginine- and glycyl-L-proline-beta-naphthylamide, were strongly cleaved by B. gingivalis and weakly cleaved by other Bacteroides strains. Since high levels of N-CBz-glycyl-glycyl-L-arginyl-aminopeptidase activity are characteristic of B. gingivalis, its measurement may be valuable in the identification of this organism in clinical samples as an aid in diagnosis and monitoring of periodontal infections. Furthermore, this and other aminopeptidases produced by B. gingivalis and other oral organisms may play a role in the tissue destruction seen in periodontal disease.

Isolation and characterization of a peptidase from an oral strain of Corynebacterium matruchotii

From the cell extract of Corynebacterium matruchotii strain ATCC 14266, a peptidase could be isolated and purified, increasing the specific activity 267 times. This enzyme with a molecular weight of 60,000 was completely inactivated by heating at 50 degrees C for 20 min, its optimum pH was found to be pH 7.5 and the isoelectric point was 4.1. The peptidase was inhibited by diisopropylfluorophosphate, phenylmethanesulfonyl fluoride, tosyl-L-lysine chloromethyl ketone, chymostatin and urea. Among various synthetic substrates tested, only benzoyl-L-arginine-p-nitroanilide and benzoyl-L-arginine ethylester were found to be hydrolyzed by this enzyme. Several proteins investigated were not hydrolyzed, but the enzyme inactivated a peptidic staphylococcal bacteriocin.

Effect of a protease derived from the oral bacterium Bacteroides loescheii on the inhibition of calcium-phosphate precipitation by human parotid saliva

A protease from the culture fluid of this microorganism was purified and characterized using DEAE-Sephadex and chromatofocusing and classified as a thiol protease with a mol. wt estimated as 27,500. It abolished the inhibitory activity of parotid saliva on the precipitation of calcium phosphate from supersaturated solutions. Such proteases may contribute to dental calculus formation.

Degradation of the human proteinase inhibitors alpha-1-antitrypsin and alpha-2-macroglobulin by Bacteroides gingivalis

Various strains of black-pigmented Bacteroides species were grown on horse blood agar and suspended in human serum. After various times of incubation the effect of the bacteria on the serum was evaluated by polyacrylamide gel electrophoresis and "rocket" immunoelectrophoresis. The formation of trichloroacetic acid-soluble material in the suspensions and the capacity of the treated sera to inhibit the activity of trypsin were also determined. The two tested strains of Bacteroides gingivalis (W83, H185) degraded most serum proteins, including the plasma proteinase inhibitors alpha-1-antitrypsin and alpha-2-macroglobulin. They did not, however, degrade alpha-1-antichymotrypsin. Bacteroides intermedius NCTC 9336, Bacteroides asaccharolyticus NCTC 9337, and an asaccharolytic oral strain different from B. gingivalis (BN11a-f) did not degrade the plasma proteinase inhibitors. These strains were, however, able to inactivate the capacity of serum to inhibit the activity of trypsin.

Characterization of a trypsin-like protease from the bacterium Bacteroides gingivalis isolated from human dental plaque

A trypsin-like, membrane-bound protease from Bacteroides gingivalis was solubilized by Triton X-100 and partially purified by a combination of DEAE-Sepharose and aminophenylmercuric Sepharose chromatography, by taking advantage of the thiol group on the enzyme. The purified enzyme hydrolysed the synthetic substrates benzoyl-L-arginine-p-nitroanilide (L-BAPA), benzoyl-D,L-arginine-beta-naphthylamide (BANA) and tosyl-L-arginine methyl ester, as well as bovine serum albumin and ovalbumin, but not tosyl-L-lysine methyl ester. The enzyme activity was enhanced by SH-reagents and was inhibited to different degrees by SH-inhibitors, chelators and microbial low-molecular-weight inhibitors such as leupeptin, antipain and chymostatin. These microbial inhibitors could be of practical use as ligands for affinity chromatography for further purification. The possible involvement of the protease in periodontal diseases is also discussed.