Isolation of a chymotrypsinlike enzyme from Treponema denticola

Surface protease of Treponema denticola hydrolyzes C3 and influences function of polymorphonuclear leukocytes

Treponema denticola is a dominant microorganism in human periodontal lesions. One of the major virulence factors of this microorganism is its chymotrypsin-like surface protease, dentilisin. The purpose of this study was to evaluate the effect of dentilisin on human polymorphonuclear leukocytes (PMNs). We used chemiluminescence to assess production of O(-)(2) by PMNs against T. denticola ATCC 35405 and dentilisin-deficient mutant K1. T. denticola ATCC 35405 induced production of O(-)(2), whereas dentilisin-deficient K1 did not. We found that chymostatin, a protease inhibitor, strongly reduced the ability of T. denticola ATCC 35405 to induce production of, O(-)(2), whereas K1 was relatively unaffected. We also used Immunoblot and ELISA to evaluate the activation of complement by this microorganism in relation to PMNs. T. denticola ATCC 35405 hydrolyzed the alpha-chain of C3, producing iC3b. Furthermore, strain ATCC 35405 induced a larger release of MMP-9 from PMNs than strain K1. Dentilisin activated PMNs via complement pathways and may play a role in establishing periodontal lesions.

Inhibition of periodontopathogen-derived proteolytic enzymes by a high-molecular-weight fraction isolated from cranberry

BACKGROUND

Porphyromonas gingivalis, Tannerella forsythia and Treponema denticola are three major aetiological agents of chronic periodontitis. The strong proteolytic activities of these bacteria are critical to their survival since their energy source is obtained from peptides and amino acids derived from proteins. In addition, proteases are important factors contributing to periodontal tissue destruction by a variety of mechanisms, including direct tissue degradation and modulation of host inflammatory responses.

OBJECTIVES

The aim of this study was to investigate the effect of non-dialysable material (NDM) prepared from cranberry juice concentrate on the proteolytic activities of P. gingivalis, T. forsythia and T. denticola.

METHODS

The effect of NDM on gingipain and dipeptidyl peptidase IV (DPP IV) activities of P. gingivalis, trypsin-like activity of T. forsythia and chymotrypsin-like activity of T. denticola was evaluated using synthetic chromogenic peptides. In addition, the capacity of P. gingivalis to degrade fluorescein-labelled type I collagen and fluorescein-labelled transferrin in the presence of NDM was evaluated by fluorometry.

RESULTS

NDM dose-dependently inhibited the proteinases of P. gingivalis, T. forsythia and T. denticola as well as type I collagen and transferrin degradation by P. gingivalis.

CONCLUSIONS

These results suggest that NDM has the potential to reduce either the proliferation of P. gingivalis, T. forsythia and T. denticola in periodontal pockets or their proteinase-mediated destructive process occurring in periodontitis.

Mutagenesis of a novel gene in the prcA-prtP protease locus affects expression of Treponema denticola membrane complexes

A novel gene was identified in the Treponema denticola prcA-prtP protease operon. Strains with mutations in either the prcA-prtP or the msp region showed altered expression of a product(s) of the other locus. Together, these results provide information on the assembly of outer membrane complexes involved in T. denticola interaction with host cells and tissue.

Outer membrane proteins of pathogenic spirochetes

Pathogenic spirochetes are the causative agents of several important diseases including syphilis, Lyme disease, leptospirosis, swine dysentery, periodontal disease and some forms of relapsing fever. Spirochetal bacteria possess two membranes and the proteins present in the outer membrane are at the site of interaction with host tissue and the immune system. This review describes the current knowledge in the field of spirochetal outer membrane protein (OMP) biology. What is known concerning biogenesis and structure of OMPs, with particular regard to the atypical signal peptide cleavage sites observed amongst the spirochetes, is discussed. We examine the functions that have been determined for several spirochetal OMPs including those that have been demonstrated to function as adhesins, porins or to have roles in complement resistance. A detailed description of the role of spirochetal OMPs in immunity, including those that stimulate protective immunity or that are involved in antigenic variation, is given. A final section is included which covers experimental considerations in spirochetal outer membrane biology. This section covers contentious issues concerning cellular localization of putative OMPs, including determination of surface exposure. A more detailed knowledge of spirochetal OMP biology will hopefully lead to the design of new vaccines and a better understanding of spirochetal pathogenesis.

Biochemical model for inflammation of the brain: the effect of iron and transferrin on monocytes and lipid peroxidation

Cerebral inflammation plays a role in diseases such as multiple sclerosis (MS), Alzheimer's disease (AD), and depression. Iron is involved in infection and inflammation through free radical production. Theoretically transferrin should prohibit iron from participating in oxidative reactions, but transferrin has also been found to promote free radical damage. We reported previously that isolation of transferrin from plasma by ion exchange column chromatography produced a broad pink protein band that subsequently separated on a gel filtration column into three proteins containing many metals. In this study some properties of the three proteins were studied in 20 volunteers. Protein 3 (identified as transferrin by nephelometry) contained the most iron while Protein 1 (called "toxiferrin") contained significantly less iron (p < 0.00001). Plasma from volunteers obtained under conditions of infection/inflammation with fever (n = 5) had a significantly increased toxiferrin to transferrin ratio compared to healthy volunteers (n = 15; p < 0.001). In vitro, Protein 2 and transferrin inhibited lipid peroxidation, while toxiferrin (possibly a protease degradation product of transferrin), enhanced lipid peroxidation. Also, toxiferrin (1 mg/mL) caused a significant increase in viability of monocytes as measured by the 3-(4,5-dimethyl-thiazol-2-yl) 2,5-diphenyl tetrazolium bromide (MTT) reduction test, as well as the morphological transformation of monocytes to macrophages.

A 43-kDa protein ofTreponema denticolais essential for dentilisin activity

A protease of Treponema denticola, dentilisin, is thought to be part of a complex with 43- and 38-kDa proteins. A sequence encoding a 43-kDa protein was located in the 3' region of the prcA gene upstream of the dentilisin gene (prtP). The 43-kDa protein was apparently generated from digestion of PrcA. To clarify the function of the protein, we constructed a mutant of the 43-kDa protein following homologous recombination. The mutant lacked detectable dentilisin activity. Immunoblot analysis demonstrated that the dentilisin protein was degraded in the mutant. The results of real-time polymerase chain reaction suggested that prtP mRNA expression in the mutant was somewhat decreased compared with the wild-type strain. These data suggest that the 43-kDa protein is involved in the stabilization of the dentilisin protein.

Two paralogous families of a two-gene subtilisin operon are widely distributed in oral treponemes

Certain oral treponemes express a highly proteolytic phenotype and have been associated with periodontal diseases. The periodontal pathogen Treponema denticola produces dentilisin, a serine protease of the subtilisin family. The two-gene operon prcA-prtP is required for expression of active dentilisin (PrtP), a putative lipoprotein attached to the treponeme's outer membrane or sheath. The purpose of this study was to examine the diversity and structure of treponemal subtilisin-like proteases in order to better understand their distribution and function. The complete sequences of five prcA-prtP operons were determined for Treponema lecithinolyticum, "Treponema vincentii," and two canine species. Partial operon sequences were obtained for T. socranskii subsp. 04 as well as 450- to 1,000-base fragments of prtP genes from four additional treponeme strains. Phylogenetic analysis demonstrated that the sequences fall into two paralogous families. The first family includes the sequence from T. denticola. Treponemes possessing this operon family express chymotrypsin-like protease activity and can cleave the substrate N-succinyl-alanyl-alanyl-prolyl-phenylalanine-p-nitroanilide (SAAPFNA). Treponemes possessing the second paralog family do not possess chymotrypsin-like activity or cleave SAAPFNA. Despite examination of a range of protein and peptide substrates, the specificity of the second protease family remains unknown. Each of the fully sequenced prcA and prtP genes contains a 5' hydrophobic leader sequence with a treponeme lipobox. The two paralogous families of treponeme subtilisins represent a new subgroup within the subtilisin family of proteases and are the only subtilisin lipoprotein family. The present study demonstrated that the subtilisin paralogs comprising a two-gene operon are widely distributed among treponemes.

Enzymatic degradation of collagen-guided tissue regeneration membranes by periodontal bacteria

Bacterial infection in the vicinity of guided tissue regeneration barrier membranes was shown to have a negative effect on the clinical outcomes of this increasingly used technique. Several oral and specifically periodontal bacteria were shown to adhere to such membranes in vivo and in vitro with a higher affinity to membranes constructed from collagen. The present study examined the role of periodontal bacteria and their enzymes in the degradation of commercially used collagen membranes. Degradation of two collagen membranes [Biomend (Calcitek, Colla-Tec Inc., Plainsboro, NJ) and Bio-Gide (Geistlich Biomaterials, Wolhousen, Switzerland)] labeled by fluorescein isothiocyanate was examined by measuring soluble fluorescence. Porphyromonas gingivalis, Treponema denticola and Actinobacillus actinomycetemcomitans and their enzymes were evaluated. Collagenase from Clostridium hystolyticum was used as a positive control. While whole cells of P. gingivalis were able to degrade both types of membranes, T. denticola could degrade Bio-Gide membranes only and A. actinomycetemcomitans whole cells could degrade none of the membranes. Fractionation of P. gingivalis cells revealed that cell membrane associated proteases were responsible for the degradation of the two collagen membranes. In T. denticola, the purified major phenylalanine protease was found to be responsible for the degradation of Bio-Gide membranes. These results suggest that proteolytic bacterial enzymes may take part in the degradation of collagen barrier membranes used for guided tissue regeneration.

Treponema denticola may stimulate both epithelial proliferation and apoptosis through MAP kinase signal pathways

Mitogen-activated protein kinases (MAP kinases) play a key role in the regulation of cell survival and death. Effects of Treponema denticola ATCC 35405 on ERK, p38 and JNK MAP kinases, and cell behavior was studied using non-keratinizing periodontal ligament epithelial cells (PLE) in vitro. Compared to Chinese hamster ovary cells, human cervix adenocarcinoma cells, human osteosacroma cells and human gingival fibroblasts, PLE cells were much more resistant to T. denticola-induced reduction in cell viability, assayed by tetrazolium and crystal violet assays. A low dose of 5 x 10(7) T. denticola cells/ml increased DNA synthesis ([3H]thymidine uptake) in PLE cells but at higher concentrations DNA synthesis was decreased. TUNEL staining analysis showed that about 50% of epithelial cells in onolayers died through apoptosis when exposed to a high dose of 10(11) T. denticola/ml for 24 h. Morphological light and electron microscopic analysis supported the idea that both apoptotic and necrotic cell death took place. Rounding, membrane damage, fragmentation and detachment were observed in selective cells of both mono- and multilayered PLE cultures challenged with T. denticola. Western blot analysis using MAP kinase phosphospecific antibodies showed that T. denticola strongly but transiently activated ERK1 and ERK2, signals mediating cell proliferation, and JNK and p38, kinases mediating apoptosis. While a specific inhibitor of the ERK MAP kinase pathway prevented the T. denticola stimulation of cell proliferation, inhibitor of p38 increased the cell numbers in T. denticola-treated cultures. The results suggest that T. denticola activates epithelial cell MAP kinase signal pathways controlling cell proliferation and cell survival. In addition, T. denticola exerts cytotoxic effects that appear to predominate at higher bacterial concentrations.

Cleavage of Treponema denticola PrcA polypeptide to yield protease complex-associated proteins Prca1 and Prca2 is dependent on PrtP

Analysis of potential virulence factors of oral spirochetes focuses on surface and secreted proteins. The Treponema denticola chymotrypsin-like protease (CTLP) is implicated in degradation of host cell molecules and contributes to tissue invasion. The CTLP complex, composed of the 72-kDa PrtP protein and two auxiliary proteins with molecular masses of approximately 40 and 30 kDa, is also involved in localization and oligomerization of the T. denticola major surface protein (Msp). The larger auxiliary protein was reported to be encoded by an open reading frame (ORF2) directly upstream of prtP. The deduced 39-kDa translation product of ORF2 contains a sequence matching the N-terminal sequence determined from one of the CTLP complex proteins. No proteins with significant homology are known, nor was information available on the third protein of the complex. DNA sequence analysis showed that ORF2 extended an additional 852 bp upstream of the reported sequence. The complete gene, designated prcA, encodes a predicted N-terminally-acylated polypeptide of approximately 70 kDa. Isogenic mutants with mutations in prtP, prcA, and prcA-prtP all lacked CTLP protease activity. The prcA mutant lacked all three CTLP proteins. The prcA-prtP mutant produced only a C-terminally-truncated 62-kDa PrcA protein. The prtP mutant produced a full-length 70-kDa PrcA. Immunoblot analysis of recombinant PrcA constructs confirmed that PrcA is cleaved to yield the two smaller proteins of the CTLP complex, designated PrcA1 and PrcA2. These data indicate that PrtP is required for cleavage of PrcA and suggest that this cleavage may be required for formation or stability of outer membrane complexes.

Role of Treponema denticola in periodontal diseases

Among periodontal anaerobic pathogens, the oral spirochetes, and especially Treponema denticola, have been associated with periodontal diseases such as early-onset periodontitis, necrotizing ulcerative gingivitis, and acute pericoronitis. Basic research as well as clinical evidence suggest that the prevalence of T denticola, together with other proteolytic gram-negative bacteria in high numbers in periodontal pockets, may play an important role in the progression of periodontal disease. The accumulation of these bacteria and their products in the pocket may render the surface lining periodontal cells highly susceptible to lysis and damage. T. denticola has been shown to adhere to fibroblasts and epithelial cells, as well as to extracellular matrix components present in periodontal tissues, and to produce several deleterious factors that may contribute to the virulence of the bacteria. These bacterial components include outer-sheath-associated peptidases, chymotrypsin-like and trypsin-like proteinases, hemolytic and hemagglutinating activities, adhesins that bind to matrix proteins and cells, and an outer-sheath protein with pore-forming properties. The effects of T. denticola whole cells and their products on a variety of host mucosal and immunological cells has been studied extensively (Fig. 1). The clinical data regarding the presence of T. denticola in periodontal health and disease, together with the basic research results involving the role of T. denticola factors and products in relation to periodontal diseases, are reviewed and discussed in this article.

Motility and chemotaxis in tissue penetration of oral epithelial cell layers by Treponema denticola

The ability to penetrate tissue is an important virulence factor for pathogenic spirochetes. Previous studies have recognized the role of motility in allowing pathogenic spirochetes to invade tissues and migrate to sites favorable for bacterial proliferation. However, the nature of the movements, whether they are random or controlled by chemotaxis systems, has yet to be established. In this study, we addressed the role of motility and chemotaxis in tissue penetration by the periodontal disease-associated oral spirochete Treponema denticola using an oral epithelial cell line-based experimental approach. Wild-type T. denticola ATCC 35405 was found to penetrate the tissue layers effectively, whereas a nonmotile mutant was unable to overcome the tissue barrier. Interestingly, the chemotaxis mutants also showed impaired tissue penetration. A cheA mutant that is motile but lacks the central kinase of the chemotaxis pathway showed only about 2 to 3% of the wild-type penetration rate. The two known chemoreceptors of T. denticola, DmcA and DmcB, also appear to be involved in the invasion process. The dmc mutants were actively motile but exhibited reduced tissue penetration of about 30 and 10% of the wild-type behavior, respectively. These data suggest that not only motility but also chemotaxis is involved in the tissue penetration by T. denticola.

The opdB locus encodes the trypsin-like peptidase activity of Treponema denticola

High levels of Treponema denticola in subgingival dental plaque are associated with severe periodontal disease. T. denticola, along with Porphyromonas gingivalis and Bacteroides forsythus, are the only cultivatable oral microorganisms that produce significant amounts of "trypsin-like" peptidase activity. The ability of subgingival plaque to hydrolyze N-alpha-benzoyl-DL-arginine-2-naphthylamide (BANA) is associated with high levels of one or more of these organisms. The purpose of this study was to identify the gene encoding trypsin-like activity in T. denticola and thus facilitate molecular-level studies of its potential role in disease. Using published peptide sequences of a T. denticola surface-associated oligopeptidase with BANA-hydrolyzing activity, we identified the gene, designated opdB, in an apparently noncoding region of the T. denticola genome unannotated contigs (11/2000; http://www.tigr.org). The opdB gene begins with a TTG start codon and encodes a 685-residue peptide with high homology to the oligopeptidase B family in prokaryotes and eukaryotes. An isogenic T. denticola opdB mutant was constructed by allelic replacement mutagenesis using an ermF/AM gene cassette. The mutant lacked BANA-hydrolyzing activity and had a slightly slower growth rate than the parent strain. This mutant will be used in future studies of interactions of T. denticola with host cells and tissue.

Proteolytic activity among various oral Treponema species and cloning of a prtP-like gene of Treponema socranskii subsp. socranskii

The proteolytic activity of 11 treponemal strains representing different phylogenetic groups was investigated by SDS-polyacrylamide gel electrophoresis with copolymerised casein, gelatin and fibrinogen as substrates. The activity was specified to be trypsin- and chymotrypsin-like by the cleavage of synthetic substrates BAPNA and SAAPFNA, respectively. Nine strains degrade casein and the synthetic substrate BAPNA. Chymotrypsin-like activity specifically inhibited by phenylmethylsulfonyl fluoride was found in four treponemes. Southern blot analysis using a Treponema socranskii subsp. socranskii-specific prtP probe confirmed the presence of prtP homologous genes in these four strains. The internal fragments of the chymotrypsin-like protease genes were cloned and sequenced after PCR amplification. Here we report the cloning of the complete prtP-like gene of T. socranskii subsp. socranskii, an organism shown to possess epidemiologic relevance in periodontitis.

Significance of detection of Porphyromonas gingivalis, Bacteroides forsythus and Treponema denticola in periodontal pockets

The relationship between the detection of Porphyromonas gingivalis, Bacteroides forsythus and Treponema denticola in subgingival plaque samples of periodontal pockets and periodontal status was evaluated using the polymerase chain reaction (PCR). A total of 165 sites in 60 periodontitis patients were examined, and the relationships between the detection of each of the three bacterial species and the pocket depth and bleeding on probing (BOP) were analyzed. The detection ratios of P. gingivalis, B. forsythus, and T. denticola in samples from adult periodontitis lesions were 75.5%, 69.8%, and 72.6%, respectively. It was found that all sites where all three microorganisms were detected were BOP positive and had greater pocket depths than those where only one or two species were found. The detection rate of B. forsythus and T. denticola decreased with age in the sites in which PD was less than 4 mm. The present study indicates that detection of a mixed infection by P. gingivalis, B. forsythus, and T. denticola strongly correlated with adult periodontitis.

Taxonomy and virulence of oral spirochetes

All oral spirochetes are classified in the genus Treponema. This genus is in the family Spirochaetaceae as in Bergey's manual of systematic bacteriology. Other generic members of the family include Spirochaeta, Cristispira and Borrelia. This conventional classification is in accord with phylogenetic analysis of the spirochetes based on 16S rRNA cataloguing. The oral spirochetes fall naturally within the grouping of Treponema. Only four species of Treponema have been cultivated and maintained reliably: Treponema denticola, Treponema pectinovorum, Treponema socranskii and Treponema vincentii. These species have valid names according to the rules of nomenclature except for Treponema vincentii, which only has had effective publication. The virulence factors of the oral spirochetes updated in this mini-review have been discussed within the following broad confines: adherence, cytotoxic effects, iron sequestration and locomotion. T. denticola has been shown to attach to human gingival fibroblasts, basement membrane proteins, as well as other substrates by specific attachment mechanisms. The binding of the spirochete to human gingival fibroblasts resulted in cytotoxicity and cell death due to enzymes and other proteins. Binding of the spirochete to erythrocytes was accompanied by agglutination and lysis. Hemolysis releases hemin, which is sequestered by an outer membrane sheath receptor protein of the spirochete. The ability to locomote through viscous environments enables spirochetes to migrate within gingival crevicular fluid and to penetrate sulcular epithelial linings and gingival connective tissue. The virulence factors of the oral spirochetes proven in vitro underscore the important role they play in the periodontal disease process. This role has been evaluated in vivo by use of a murine model.

Molecular pathogenesis of the cell surface proteins and lipids from Treponema denticola

Treponema denticola, frequently isolated from the human oral cavity, is thought to be a major pathogen of human periodontal disease. Recent developments in molecular analysis have clarified the surface structure of this microorganism and the characteristics of its pathogenic factors. Structural analysis of the outer sheath showed T. denticola to have a new type of outer membrane lipid. Limited exposure of the major outer sheath protein is suggested by electron-microscopic analysis. A protease-deficient mutant has revealed the roles of the protease in the organization of the outer sheath material and in T. denticola pathogenicity. The surface features that contribute to the pathogenicity of T. denticola in periodontal disease are gradually being elucidated, and are reviewed.

Multiple forms of the major phenylalanine specific protease in Treponema denticola

The 160, 190 and 270 kDa outer sheath proteases of Treponema denticola ATCC 35404 were found to be multiple forms of the major 91 kDa phenylalanine protease (PAP) by immunoblotting using anti-91 kDa specific antibodies. Multiple forms of the phenylalanine protease were also found in 2 other T. denticola strains studied, ATCC 33520 and the clinical isolate GM-1. Protein, proteolytic and Western blot analyses using antibodies against the PAP and the major outer sheath protein (MSP) indicated that the 190 and 270 kDa proteases were protein complexes formed by the MSP and the PAP. These complexes dissociated by storage in 0.3% or higher SDS concentrations. The purified PAP was found to completely degrade keratin, but was unable to degrade native actin either in its monomeric or polymerized form. The association of the MSP adhesin with a protease capable of degrading host native proteins may benefit the obtention of protein-based nutrients necessary to support the growth of these treponemes. These complexes may also play a role in the structural organization of T. denticola outer sheath.

Treponema denticola outer membrane enhances the phagocytosis of collagen-coated beads by gingival fibroblasts

Human gingival fibroblasts (HGFs) degrade collagen fibrils in physiological processes by phagocytosis. Since Treponema denticola outer membrane (OM) extract perturbs actin filaments, important structures in phagocytosis, we determined whether the OM affects collagen phagocytosis in vitro by HGFs. Phagocytosis was measured by flow cytometric assessment of internalized collagen-coated fluorescent latex beads. Confluent HGFs pretreated with T. denticola ATCC 35405 OM exhibited an increase in the percentage of collagen phagocytic cells (phagocytosis index [PI]) and in the number of beads per phagocytosing cell (phagocytic capacity [PC]) compared with untreated controls. The enhancement was swift (within 15 min) and was still evident after 1 day. PI and PC of HGFs for bovine serum albumin (BSA)-coated beads were also increased, indicating a global increase in phagocytic processes. These results contrasted those for control OM from Veillonella atypica ATCC 17744, which decreased phagocytosis. The T. denticola OM-induced increase in bead uptake was eliminated by heating the OM and by depolymerization of actin filaments by cytochalasin D treatment of HGFs. Fluid-phase accumulation of lucifer yellow was enhanced in a saturable, concentration-dependent, transient manner by the T. denticola OM. Our findings were not due to HGF detachment or cytotoxicity in response to the T. denticola OM treatment since the HGFs exhibited minimal detachment from the substratum; they did not take up propidium iodide; and there was no change in their size, granularity, or content of sub-G1 DNA. We conclude that a heat-sensitive component(s) in T. denticola OM extract stimulates collagen phagocytosis and other endocytic processes such as nonspecific phagocytosis and pinocytosis by HGFs.

Dentilisin activity affects the organization of the outer sheath of Treponema denticola

Prolyl-phenylalanine-specific serine protease (dentilisin) is a major extracellular protease produced by Treponema denticola. The gene, prtP, coding for the protease was recently cloned and sequenced (K. Ishihara, T. Miura, H. K. Kuramitsu, and K. Okuda, Infect. Immun. 64:5178-5186, 1996). In order to determine the role of this protease in the physiology and virulence of T. denticola, a dentilisin-deficient mutant, K1, was constructed following electroporation with a prtP-inactivated DNA fragment. No chymotrypsin-like protease activity was detected in the dentilisin-deficient mutant. In addition, the high-molecular-mass oligomeric protein characteristic of the outer sheath of the organism decreased in the mutant. Furthermore, the hydrophobicity of the mutant was decreased, and coaggregation of the mutant with Fusobacterium nucleatum was enhanced compared to that of the wild-type organism. The results obtained with a mouse abscess model system indicated that the virulence of the mutant was attenuated relative to that of the wild-type organism. These results suggest that dentilisin activity plays a major role in the structural organization of the outer sheath of T. denticola. The loss of dentilsin activity and the structural change in the outer sheath affect the pathogenicity of T. denticola.

Purification and characterization of a protease from Actinobacillus pleuropneumoniae serotype 1, an antigen common to all the serotypes

A high molecular-mass proteolytic enzyme of Actinobacillus pleuropneumoniae serotype 1, was purified from culture supernatants (CSN) by using DEAE-cellulose and sepharose-4B-gelatin chromatography. In 10% SDS-polyacrylamide gels copolymerized with porcine gelatin, the protease showed a single band of activity of > 200 kDa. However, minor molecular-mass proteolytic bands were observed when the protease was electrophoresed in the presence of either 5% beta-mercaptoethanol, 50 mM dithiothreitol, or 0.25 M urea. Furthermore, when the > 200-kDa purified protein was passed through a sucrose gradient, several bands with proteolytic activity were found: 62, 90, 190, and 540 kDa. The proteolytic activity was increased in the presence of calcium or zinc and was not affected after being heated at 90 degrees C for 5 min. Proteolytic activities were also observed in CSN from all A. pleuropneumoniae serotypes and biotypes. The purified protease hydrolyzed porcine IgA and IgG in vitro. In addition, by immunoblot the protease was recognized by serum of naturally infected pigs with serotypes 1 and 5, and by serum of pigs experimentally infected with serotypes 1, 2, 8, or 9. Serum of a pig vaccinated with CSN of a serotype 3 strain also recognized the protease, but not sera of pigs vaccinated with a bacterin (serotype 1). Proteins from CSN of all the serotypes, which were precipitated with 70% (NH4)2SO4, were recognized by a polyclonal antibody raised against the purified protease. Taken together these results indicate that an antigenic protease is produced in vivo by all the serotypes of A. pleuropneumoniae. The results indicate that proteases could have a role in the disease and in the immune response of pigs infected with A. pleuropneumoniae.

Mutagenesis of outer membrane virulence determinants of the oral spirochete Treponema denticola

The pore-forming major surface protein (Msp) and the chymotrypsin-like protease (CTLP) of Treponema denticola ATCC 35405 have been implicated in periodontal pathogenicity. Allelic replacement mutations were constructed at two sites in the msp gene and at one site in the CTLP locus. All mutant strains lacked the Msp hexagonal array outer membrane ultrastructure. Strain CKE, in which the locus encoding CTLP was disrupted, produced no CTLP and had aberrant Msp expression. The msp mutant MHE lacked Msp, and produced increased levels of CTLP. In contrast, msp mutant MPE made small amounts of a truncated Msp, but produced no CTLP. Interactions between Msp and CTLP in transport or assembly of the outer membrane complex are proposed.

Cytopathic effects of the major surface protein and the chymotrypsinlike protease of Treponema denticola

Prominent antigens of Treponema denticola have been suggested to be mediators of the cytopathic effects typically seen in periodontal disease. In the present study of the T. denticola major surface protein (Msp) and the surface-expressed chymotrypsinlike protease complex (CTLP), we characterized the ability of these proteins to adhere to and lyse epithelial cells. Msp and CTLP were closely associated in spirochete outer membranes. Purified Msp, both native and recombinant, and CTLP bound to glutaraldehyde-fixed periodontal ligament epithelial cells. Adherence of Msp was partially blocked by specific antibodies. Adherence of CTLP was partially blocked by serine protease inhibitors and was further inhibited by specific antibodies. Both native Msp and CTLP were cytotoxic toward periodontal ligament epithelial cells, and their cytotoxicity was inhibited by the same treatments that inhibited adherence. Msp, but not CTLP, lysed erythrocytes. Msp complex (partially purified outer membranes free of protease activity) was cytotoxic toward a variety of different cell types. Pore-forming activities of recombinant Msp in black lipid model membrane assays and in HeLa cell membranes were similar to those reported for the native protein, supporting the hypothesis that Msp cytotoxicity was due to its pore-forming activity.

Filamentous actin disruption and diminished inositol phosphate response in gingival fibroblasts caused by Treponema denticola

Previous reports have shown that Treponema denticola causes rearrangement of filamentous actin (F-actin) in human gingival fibroblasts (HGF). The purpose of this investigation was to determine the effect of T. denticola on the generation of inositol phosphates (IPs) in relation to a time course for F-actin disruption in HGF. Cultured HGF were exposed to washed cells of T. denticola ATCC 35405 for 140 min. Changes in the fluorescence intensity of rhodamine-phalloidin-labeled F-actin in serial optical sections of single HGF were quantified by confocal microscopy image analysis. The percentage of cells with stress fiber disruption was also determined by fluorescence microscopy. Challenge with T. denticola caused a significant reduction in F-actin within the first hour, especially at the expense of F-actin in the ventral third of the cells, and a significant increase in the percentage of HGF with altered stress fiber patterns. Significant concentration-dependent disruption of stress fibers was also caused by HGF exposure to a Triton X-100 extract of T. denticola outer membrane (OM). IPs were measured by a radiotracer assay based on the incorporation of myo-[3H]inositol into IPs in HGF incubated with LiCl to inhibit endogenous phosphatases. HGF challenge with several strains of T. denticola and the OM extract of T. denticola ATCC 35405 resulted in a diminished accumulation of radiolabeled IPs relative to both 15 and 1% fetal bovine serum, which served as strongly positive and background control agonists, respectively. The significantly diminished IP response to T. denticola ATCC 35405 occurred within 60 min, concomitant with significant reduction of total F-actin and disruption of stress fibers. Pretreatment with the proteinase inhibitor phenylmethylsulfonyl fluoride, which had previously been found to block T. denticola's degradation of endogenous fibronectin and detachment of HGF from the extracellular matrix, had little effect on F-actin stress fiber disruption and the IP response. Therefore, in addition to its major surface chymotrypsin-like properties, T. denticola expresses cytopathogenic activities that diminish the generation of IPs during the time course associated with significant cytoskeletal disruption in fibroblasts.

Virulence characteristics of oral treponemes in a murine model

This study was designed to investigate the virulence characteristics of Treponema denticola, T. socranskii, T. pectinovorum, and T. vincentii following challenge infection of mice. These microorganisms induced well-demarcated, dose-dependent, raised subcutaneous (s.c.) abscesses which were similar in time of onset, lesion progression, and duration of healing. Only viable cells were capable of inducing these characteristic s.c. abscesses. Histological examination of the skin lesion 3 and 5 days postinfection revealed abscess formation in the s.c. tissues, and abundant spiral organisms were demonstrated to be present in the abscess. Host resistance modulation by dexamethasone (neutrophil alteration) and cyclophosphamide (neutrophil depletion) pretreatment had a minimal effect on the virulence expression by any of these treponemes. The T. denticola isolates demonstrated significant trypsin-like protease (TLPase) activity, while both T. socranskii and T. vincentii were devoid of this activity. Interestingly, T. pectinovorum strains were heterogeneous with respect to TLPase as high producers, low producers, and nonproducers. However, no differences in lesion formation were noted regardless of whether the species expressed this proteolytic activity or whether treatment with N alpha-p-tosyl-L-lysine chloromethyl ketone (TLCK) and dithiothreitol was performed. These results showed that (i) a murine model may be used to evaluate virulence expression by oral treponemes; (ii) while TLPase activity varies among the oral treponemes, this protease does not appear to participate in abscess induction in the mouse model; and (iii) T. pectinovorum strains show variation in TLPase activity.

An inexpensive solid medium for obtaining colony-forming units of oral spirochetes

A method for the enumeration of colony-forming units of oral anaerobic spirochetes in new oral spirochete agarose (NOS-A) medium was described recently. However, the high cost of agarose limits the extent to which large assays can be carried out. Accordingly, a search for an inexpensive gelling agent that remains molten at 37 degrees C and gels at 25 degrees C was undertaken. Varying amounts of Noble agar or Bacto agar (0.5 to 1.5%, w/v) were mixed with varying amounts of gelatin (0.5 to 1.0%, w/v) in NOS medium. NOS medium containing 0.5% gelatin-0.5% Noble agar (NOS-GN) or 0.5% gelatin-0.5% Bacto agar (NOS-GB) met the above criteria. NOS-GN and NOS-GB media yielded higher colony-forming units with Treponema denticola than NOS-A medium in that order. However, all three media, NOS-GN, NOS-GB and NOS-A, performed equally well in the recovery of viable counts of T. vincentii. The NOS-GN medium was not liquefied by subgingival bacteria or two gelatinase-producing species of bacteria, Bacillus subtilis and Staphylococcus aureus. Thus NOS-GN medium is the recommended medium both in cost and performance for obtaining colony counts of spirochetes.

Cloning, expression, and sequencing of a protease gene from Bacteroides forsythus ATCC 43037 in Escherichia coli

We have isolated and characterized an N-benzoyl-Val-Gly-Arg-p-nitroanilide-specific protease gene, designated prtH, from Bacteroides forsythus ATCC 43037. Nucleotide sequencing of the DNA insert from the clone (hereafter referred to as clone FST) revealed that the protease activity corresponded to an open reading frame consisting of 1,272 bp coding for a 47.8-kDa protein. When plasmid pFST was used as a probe in Southern hybridization, Sau3AI-digested chromosomal DNA of B. forsythus ATCC 43037 as well as the chromosomal DNAs of the isolated strains Ta4, TR5, and YG2 showed 0.6- and 0.8-kb hybridizing bands. The cell-free extracts of clone FST showed hemolytic activity on human blood cells. The hydrolytic activity of cell extracts of the pFST clone was inhibited by p-toluenesulfonyl-L-lysine chloromethyl ketone hydrochloride, leupeptin, N-ethylmaleimide, iodoacetic acid, iodoaceteamide, and EDTA.

Activation of the interleukin-1beta precursor by Treponema denticola: a potential role in chronic inflammatory periodontal diseases

There are several indications suggesting that interleukin-1beta (IL-1beta) may play an important role in inflammatory periodontal diseases. We hypothesized that periodontal sites would represent a unique combination of both cellular sources of IL-1beta precursor (pro-IL-1beta) and microbial proteases and proposed that Treponema denticola, a suspected periodontal pathogen, would play a critical role in the inflammatory nature of adult chronic periodontitis by activating pro-IL-1beta. The aim of this study was thus to demonstrate the proteolytic cleavage and activation of the inactive precursor pro-IL-1beta by T. denticola. After incubation of bacterial cells with recombinant pro-IL-1beta, proteolytic cleavage was monitored by Western immunoblotting, and the biological activity of the digestion products was tested in a bioassay. We report here that T. denticola can cleave pro-IL-1beta to yield two fragments with molecular masses of 18 and 19 kDa. Cleavage products showed a dose-dependent biological activity in the thymocyte proliferation bioassay, and this activity was inhibited by anti-IL-1beta neutralizing antibodies. These results suggest that T. denticola may have a proinflammatory role in periodontal diseases.

Characterization of protease activities in Capnocytophaga spp., Porphyromonas gingivalis, Prevotella spp., Treponema denticola and Actinobacillus actinomycetemcomitans

Protease activities in cell sonicates of defined bacterial strains were examined using peptide substrates and class-specific inhibitors. Capnocytophaga spp. all produced serine dipeptidyl peptidase activity and arginine/lysine, elastase- and chymotrypsin-like enzymes with some metalloprotease characteristics. The elastase-like activity was strongest in Capnocytophaga sputigena, but the others were greatest in Capnocytophaga gingivalis. The latter also had a separate arginine-specific enzyme which appeared not to be present in the other two species. Porphyromonas gingivalis showed serine dipeptidyl peptidase activity and very strong arginine and lysine cysteine protease activities. Prevotella spp. had inhibitor-resistant dipeptidyl peptidase activity and arginine cysteine protease activity that was much weaker but biochemically similar to P. gingivalis. Treponema denticola possessed a strong trypsin-like serine protease activity as well as very weak dipeptidyl peptidase and chymotrypsin-like activities that were sensitive to some cysteine protease reagents. Actinobacillus actinomycetemcomitans showed a novel alanine- and lysine-specific activity, but its nature was unclear.

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.

Membrane components of Treponema denticola trigger proteinase release from human polymorphonuclear leukocytes

Tissue destruction during periodontitis is believed to be primarily brought about by leukocyte proteinases. We postulate that oral spirochetes cause discharge of polymorphonuclear leukocyte (PMN) lysosomal enzymes. Effects of Treponema denticola 53-kDa outer membrane protein, lipopolysaccharide (LPS), and peptidoglycan on degranulation of matrix metalloproteinases (MMP)-8 (collagenase) and -9 (gelatinase), cathepsin G, and elastase by human peripheral blood PMNs were studied by specific enzyme assays and Western blot analysis. T. denticola 53-kDa kDa outer membrane protein was found to be a particularly efficient inducer of MMP-8 release. The induction was comparable with that of phorbol myristate acetate, a known inducer of PMN specific granule discharge. All of the treponemal substances, most notably the 53-kDa protein and LPS, induced release of MMP-9, a component of C-type granules. Both collagenase and gelatinase released from PMNs were mostly in active forms. Release of cathepsin G and elastase was also observed with the 53-kDa protein treatment. The other T. denticola substances did not induce release of these serine proteinases. Lactate dehydrogenase was not released from PMNs by the treatments, indicating that the degranulation was specific and not caused by toxic effects of the substances. This was confirmed by transmission electron microscopy of PMNs treated with the 53-kDa protein that showed rapid vacuole formation and cell shape changes but no disintegration of the cells. Thus, T. denticola may participate in the PMN-dependent extracellular matrix degradation during the course of periodontal inflammation by triggering the secretion and activation of matrix metalloproteinases.

Characterization of the Treponema denticola prtP gene encoding a prolyl-phenylalanine-specific protease (dentilisin)

A chymotrypsin-like protease from Treponema denticola ATCC 35405 was purified by chromatographic techniques. The purified enzyme consisted of three polypeptides (38, 43, and 72 kDa). The protease exhibited specificity for peptide bonds containing phenylalanine and proline at the P1 and P2 positions, respectively, and was classified as a serine protease on the basis of inhibition studies. Naturally occurring protease inhibitors such as alpha1-antitrypsin and alpha1-antichymotrypsin had no effect on enzymatic activity. The enzyme degraded fibronectin, alpha1-antitrypsin, and gelatin while weakly degrading the immunoglobulin G heavy chain and type IV collagen. N-terminal amino acid sequences were determined for the 43- and 72-kDa proteins. On the basis of these sequences, the genes coding for the 43- and 72-kDa proteins were isolated and sequenced. The open reading frame which codes for the 72-kDa protein was designated prtP. This gene consists of 2,169 bp and codes for a protein with an Mr of 77,471. The protein appeared to be composed of a signal peptide region followed by a prosequence and the mature protein domain. The deduced amino acid sequence exhibited similarity with that of the Bacillus subtilis serine protease subtilisin. The deduced properties of the sequence suggest that the 72-kDa protein is a chymotrypsin-like protease. However, the nature and function of the 43-kDa protein have not yet been determined.

The major surface protein complex of Treponema denticola depolarizes and induces ion channels in HeLa cell membranes

The oral spirochete Treponema denticola is closely associated with periodontal diseases in humans. The 53-kDa major surface protein (Msp) located in the outer membrane of T. denticola serovar a (ATCC 35405) has both pore-forming activity and adhesin activity. We have used standard patch clamp recording methods to study the effects of a partially purified outer membrane complex containing Msp on HeLa cells. The Msp complex was free of the chymotrypsin-like proteinase also found in the outer membrane of T. denticola. Msp bound to several HeLa cell proteins, including a 65-kDa surface protein and a 96-kDa cytoplasmic protein. The Msp complex depolarized and increased the conductance of the HeLa cell membrane in a manner which was not strongly selective for Na+, K+, Ca2+, and Cl- ions. Cell-attached patches of HeLa cell membrane exposed to Msp complex exhibited short-lived channels with a slope conductance of 0.4 nS in physiologically normal saline. These studies show that Msp binds both a putative epithelial cell surface receptor and cytoplasmic proteins and that the Msp complex can form large conductance ion channels in the cytoplasmic membrane of epithelial cells. These properties may contribute to the cytopathic effects of T. denticola on host epithelial cells.

Hyaluronan, a possible ligand mediating Treponema denticola binding to periodontal tissue

Binding of Treponema denticola ATCC 35405 to glycosaminoglycans, fibrinogen, type I collagen and porcine periodontal ligament epithelial cells was studied using an enzyme-linked immunosorbent assay. T. denticola bound to hyaluronan (hyaluronic acid) and its hexameric fragments. whereas little or no binding was detected to chondroitin-4-sulfate or dermatan sulfate proteoglycan. Binding of T. denticola to hyaluronan gradually increased during the 2-h incubation time. In contrast, binding to fibrinogen and type I collagen was more rapid, peaking within 5 min. T. denticola also bound to microbeads coated with hyaluronan and formed visible aggregates in solution. Pretreatment of the bacteria with hyaluronan or fibrinogen inhibited binding to hyaluronan. Gelatin, bovine serum albumin, chondroitin-4-sulfate, chondroitin-6-sulfate, heparin, dermatan sulfate, glucuronic acid, N-acetylglucosamine and N-acetyl-galactosamine did not inhibit binding. Binding was also inhibited by heating T. denticola and by pretreatment of the spirochetes with sodium periodate, phenylmethylsulfonyl fluoride, and p-chloromercurybenzoic acid. All these treatments also inhibited the chymotrypsin-like activity of T. denticola. Hyaluronan strongly inhibited binding of T. denticola to epithelial cells, whereas the other glycosaminoglycans and N-acetyl-glucosamine did not. The results show that T. denticola binds to hyaluronan, possibly by a mechanism involving the chymotrypsin-like surface protein of T. denticola.

Sequence analysis, expression, and binding activity of recombinant major outer sheath protein (Msp) of Treponema denticola

The gene encoding the major outer sheath protein (Msp) of the oral spirochete Treponema denticola ATCC 35405 was cloned, sequenced, and expressed in Escherichia coli. Preliminary sequence analysis showed that the 5' end of the msp gene was not present on the 5.5-kb cloned fragment described in a recent study (M. Haapasalo, K. H. Müller, V. J. Uitto, W. K. Leung, and B. C. McBride, Infect. Immun. 60:2058-2065,1992). The 5' end of msp was obtained by PCR amplification from a T. denticola genomic library, and an open reading frame of 1,629 bp was identified as the coding region for Msp by combining overlapping sequences. The deduced peptide consisted of 543 amino acids and had a molecular mass of 58,233 Da. The peptide had a typical prokaryotic signal sequence with a potential cleavage site for signal peptidase 1. Northern (RNA) blot analysis showing the msp transcript to be approximately 1.7 kb was consistent with the identification of a promoter consensus sequence located optimally upstream of msp and a transcription termination signal found downstream of the stop codon. The entire msp sequence was amplified from T. denticola genomic DNA and cloned in E. coli by using a tightly regulated T7 RNA polymerase vector system. Expression of Msp was toxic to E. coli when the entire msp gene was present. High levels of Msp were produced as inclusion bodies when the putative signal peptide sequence was deleted and replaced by a vector-encoded T7 peptide sequence. Recombinant Msp purified to homogeneity from a clone containing the full-length msp gene adhered to immobilized laminin and fibronectin but not to bovine serum albumin. Attachment of recombinant Msp was decreased in the presence of soluble substrate. Attachment of T. denticola to immobilized laminin and fibronectin was increased by pretreatment of the substrate with recombinant Msp. These studies lend further support to the hypothesis that Msp mediates the extracellular matrix binding activity of T. denticola.

Degradation of host protease inhibitors and activation of plasminogen by proteolytic enzymes from Porphyromonas gingivalis and Treponema denticola

Bacterial proteases may participate in the pathogenesis of periodontal diseases through their action on host proteins. In the present study, the ability of selected periodontopathogens, as well as two proteases isolated from Porphyromonas gingivalis and Treponema denticola, to degrade host protease inhibitors was evaluated. The activation of human plasminogen by the two bacterial proteases was also investigated. Proteolytic breakdown of host protease inhibitors (alpha-1-antitrypsin, antichymotrypsin, alpha 2-macroglobulin, antithrombin III, antiplasmin and cystatin C) was evaluated by SDS-PAGE. The 80 kDa trypsin-like protease of P. gingivalis completely digested the six protease inhibitors under investigation, whereas the 95 kDa chymotrypsin-like protease of T. denticola was slightly less active, more particularly on alpha 2-macroglobulin and cystatin C. When whole cells from a number of oral bacterial species were tested, the most significant degradation was obtained with P. gingivalis, T. denticola, Prevotella intermedia, Prevotella nigrescens and Capnocytophaga spp. Peptostreptococcus micros and Propionibacterium acnes had only some degradative activity on selected inhibitors, whereas three bacterial species, Actinobacillus actinomycetemcomitans, Bacteroides forsythus and Fusobacterium nucleatum, had no effect on the protease inhibitors. The 80 kDa protease of P. gingivalis demonstrated strong plasminogen activation, whereas no such activity was associated with the 95 kDa protease of T. denticola. This study indicates the high potential of some periodontal pathogens to destroy protease inhibitors and activate plasminogen. This may result in an uncontrolled degradation of periodontal tissues and a rapid progression of the disease.

Proteolytic artifacts in SDS-PAGE analysis of selected periodontal pathogens

The aim of the study was to examine whether proteolytic artifacts, which result in a loss and poor resolution of protein bands, occur during sodium dodecyl sulfate (SDS)-polyacrylamide gel electrophoresis analysis of cellular proteins from selected proteolytic (Porphyromonas gingivalis, Prevotella nigrescens and Treponema denticola) and non-proteolytic (Fusobacterium nucleatum) bacteria. Conditions to limit or prevent proteolysis were also investigated. Bacterial cells were incubated in solubilizing buffer (SDS+ beta mercaptoethanol) at room temperature for various periods of time before boiling. A control assay consisted of trichloroacetic acid-treated bacterial cells. Cellular proteins were separated by electrophoresis and stained with Coomassie blue. Proteolysis occurred very rapidly in the case of P. gingivalis (< 30 s), whereas a longer incubation time (> 1 h) was required to observe similar effects in P. nigrescens and T. denticola. No proteolysis was observed for F. nucleatum. In all cases, heat (100 degrees C) and low pH (< 4) treatments of bacterial cells could avoid production of proteolytic artifacts. Incorporation of specific protease inhibitors before solubilization of bacteria could also prevent proteolysis. More particularly, N-alpha-p-tosyl-L-lysine chloromethyl ketone (TLCK), iodoacetamide and diisopropylfluorophosphate (50 mM) were highly efficient for P. gingivalis, P. nigrescens and T. denticola, respectively. When outer membranes of P. gingivalis were prepared in the presence of TLCK, numerous additional protein brands, not seen in the absence of TLCK, were detected. The present study suggests that specific protease inhibitors, effective in preventing proteolysis, should be identified and added during cell fractionation and protein purification procedures.

Proteases of Treponema denticola outer sheath and extracellular vesicles

Electron microscopical observations of the oral periodontopathogen Treponema denticola show the presence of extracellular vesicles bound to the bacterial surface or free in the surrounding medium. Extracellular vesicles from T. denticola ATCC 35404, 50 to 100 nm in diameter, were isolated and further characterized. Protein and proteolytic patterns of the vesicles were found to be very similar to those of isolated T. denticola outer sheaths. They were enriched with the major outer sheath polypeptides (molecular sizes, 113 to 234 kDa) and with outer sheath proteases of 91, 153, 173, and 228 kDa. These findings indicate that treponemal outer sheath vesicles contain the necessary adhesins and proteolytic arsenal for adherence to and damage of eucaryotic cells and mammalian matrix proteins. The major outer sheath- and vesicle-associated protease of T. denticola ATCC 35404 was purified and characterized. The purified enzyme had a molecular size of 91 kDa, and it dissociated into three polypeptides of 72, 38, and 35 kDa upon heating in the presence of sodium dodecyl sulfate with or without a reducing agent. The activity of the enzyme could be inhibited by diisopropylfluorophosphate, phenylmethylsulfonyl fluoride, and phenylboronic acid. The value of the second-order rate constant of the protease inactivation by phenylmethylsulfonyl fluoride was 0.48 x 10(4) M(-1) min-1. Inhibition of the enzyme by phenylboronic acid was rapid (< 1 min) and pH dependent. These data strongly suggest that this major surface proteolytic activity belongs to a family of serine proteases.

Cytopathic effects of Treponema denticola chymotrypsin-like proteinase on migrating and stratified epithelial cells

The effects of Treponema denticola and its outer membrane-bound chymotrypsin-like proteinase on periodontal ligament epithelial cell cultures at different stages of maturity were studied. In sparse cultures with migrating epithelial cells, large intracellular vacuoles were formed rapidly following exposure to live T. denticola. Treponemes showing structural damage were seen occasionally inside membrane-bound vesicles. Intensive membrane blebbing occurred in infected cells and continued for up to 48 h before the cell died. Blebbing could also be induced by a purified chymotrypsin-like proteinase of T. denticola. Cortical actin and alpha-actinin of the bacterium-treated cells showed disorganization, and pericellular fibronectin was degraded by both whole T. denticola and the isolated proteinase. Epithelial cells with well-formed lateral cell contacts appeared to be more resistant to the effects of T. denticola than migrating isolated cells. In multilayer epithelial cultures, adhesion of T. denticola and membrane blebbing were observed infrequently. There was no evidence of invasion of T. denticola into epithelial multilayers. However, immunogold electron microscopy showed rapid transport of T. denticola chymotrypsin-like proteinase into newly formed large intracellular vacuoles within the epithelial layers. These vacuoles were lined by membranes studded with ribosomes. T. denticola-treated epithelial multilayers had loose cell contacts, collapsed intercellular spaces, and increased permeability. Through its capacity to cause these unique cytopathic effects, the chymotrypsin-like proteinase of T. denticola has the potential to contribute to the initiation of periodontal disease.

Role of the chymotrypsin-like membrane-associated proteinase from Treponema denticola ATCC 35405 in inactivation of bioactive peptides

The ability of washed whole cells of Treponema denticola ATCC 35405 to hydrolyze (inactivate) substance P, bradykinin, and angiotensin I was studied. Substance P was attacked primarily at the Phe-8-Gly-9 bond by a chymotrypsin-like proteinase (CTLP), at Pro-4-Gln-5 by an endo-acting prolyl oligopeptidase (POPase), and at Gln-5-Gln-6 by an endopeptidase (FALGPA-peptidase). Bradykinin was cleaved at Phe-5-Ser-6 by the FALGPA-peptidase and at Pro-7-Phe-8 by the POPase. Angiotensin I was rapidly converted to angiotensin II by the CTLP, and both angiotensin I and angiotensin II were further hydrolyzed at Pro-7-Phe-8 by the POPase. All these enzymes were assumed to be cell associated and were easily extracted with a mild (0.05 to 0.1%) Triton X-100 treatment. Because it was conceivable that the hydrolysis of substance P at the Phe-8-Gly-9 bond was catalyzed by a CTLP described earlier (V.-J. Uitto, D. Grenier, E. C. S. Chan, and B. C. McBride, Infect. Immun. 56:2717-2722, 1988), the enzyme was purified to homogeneity by means of conventional fast protein liquid chromatography procedures. For kinetic studies, Phe-8(4-nitro)-substance P (NSP) (absorption maximum at 309.2 nm, epsilon = 545 M-1 cm-1) was synthesized to replace substance P as a substrate in kinetic studies. In reversed-phase chromatography, both NSP and substance P gave identical results with both whole cells and the purified enzyme. The CTLP has a mass of 95 kDa, and its activity is suggested to be based on an active seryl residue, on an active imidazole group, and on an active carboxyl group but not on metal cations. The enzyme hydrolyzes N-succinyl-L-Ala-L-Ala-L-Pro-L-Phe-p-nitroaniline (SAAPFNA, a typical chymotrypsin substrate) at a high rate and several proteins, such as calf thymus histone, human plasma fibrinogen, milk caseins, and gelatin. Among the substrates tested, substance P showed the highest affinity (Km = 0.22 mM) for the purified enzyme. Depending on conditions, clinically applicable chlorhexidine levels (3.2 mmol/liter, or 0.2%) strongly activated (up to fourfold) the hydrolysis of SAAPFNA by whole cells and the purified CTLP. The hydrolysis of NSP by whole cells and purified CTLP was slightly inhibited by chlorhexidine. The results demonstrated the versatility and the effectiveness of the outer membrane of T. denticola in occasioning a rapid breakdown and inactivation of human bioactive peptides and other peptidolytic catalyses.(ABSTRACT TRUNCATED AT 400 WORDS)

Physical map of the Treponema denticola circular chromosome

A physical map of the Treponema denticola ATCC 33520 genome was constructed by pulsed-field gel electrophoresis and DNA hybridization. The organism possesses a single, circular chromosome of approximately 3.0 Mbp and a 2.6-kbp circular plasmid, pTD1. The physical map of the A+T-rich genome was constructed with the rare-cutting restriction enzymes AscI, NotI, and SrfI, which have 8-bp G+C-rich recognition sites. The genes flgE, tdpA, and prtB encoding the flagellar hook protein, a 53-kDa immunogenic protein, and chymotrypsinlike protease, respectively, were located on the map. This treponeme was found to have two copies of each of the rRNA genes, as has been found to be the case for both Treponema phagedenis and Treponema pallidum.

Cloning and expression of a neutral phosphatase gene from Treponema denticola

We have isolated and characterized a neutral phosphatase gene, phoN, from Treponema denticola ATCC 35405. The gene was isolated from a T. denticola clone bank constructed in the medium-copy-number plasmid vector pMCL19. Subcloning and nucleotide sequencing of the DNA insert from one phosphatase clone, pTph14, revealed that the activity corresponded to an open reading frame consisting of 1,027 bp coding for a 37.9-kDa protein. Hydrophobicity analysis indicated that the protein exhibits some hydrophobic regions. Indeed, partial purification of the phosphatase suggested that the enzyme was membrane associated both in T. denticola and in the Escherichia coli clone. The pH optimum of the enzyme, approximately pH 6.4, indicated that it corresponded to a neutral phosphatase activity from T. denticola. An examination of possible natural substrates for the enzyme suggested that this enzyme hydrolyzes nucleoside di- and triphosphates. Northern (RNA) blot analysis revealed that this phosphatase gene is not likely to be present in an operon structure.