Biomedical subjects

J Potempa

Publications and source records attributed to J Potempa.

At least 19 recordsLinked to original sources

PubMed2006

A new insight into phagocytosis of apoptotic cells: proteolytic enzymes divert the recognition and clearance of polymorphonuclear leukocytes by macrophages.

The recognition of phosphatidylserine (PS) on the surface of any apoptotic cell is considered to be a key event for its clearance. We challenge this concept by showing that pretreatment of neutrophils with either host or bacterial protease affects their uptake by human monocyte-derived macrophages without having an effect on cell-surface PS presentation. Specifically, whereas preincubation of apoptotic neutrophils with cathepsin G or thrombin significantly inhibited their uptake, gingipains R or clostripain enhanced phagocytosis by macrophages. Moreover, bacterial proteinases sensitized healthy neutrophils for uptake by macrophages, whereas endogenous proteinases were unable to elicit this effect. This stimulation was apparently owing to the combined effect of proteolytic cleavage of an antiphagocytic signal (CD31) and the generation of a novel 'eat-me' signal on the neutrophil surface. These results argue that neutrophil recognition and phagocytosis by macrophages is mediated by a protein ligand whose proteolytic modification could affect the local inflammatory process.

Adhesins, Bacterial↗

PubMed2006

The HA2 haemagglutinin domain of the lysine-specific gingipain (Kgp) of Porphyromonas gingivalis promotes micro-oxo bishaem formation from monomeric iron(III) protoporphyrin IX.

The lysine- and arginine-specific gingipains (Kgp, and RgpA and RgpB) are the major proteinases produced by the black-pigmented periodontopathogen Porphyromonas gingivalis. They play a role in degrading host proteins, including haemoglobin, from which is formed the mu-oxo bishaem complex of iron(III) protoporphyrin IX, [Fe(III)PPIX]2O, the major haem component of the black pigment. Kgp and RgpA bind haem and haemoglobin via the haemagglutinin-adhesin 2 (HA2) domain, but the role of this domain in the formation of mu-oxo bishaem-containing pigment is not known. UV-visible spectroscopy was used to examine the interaction of iron(III) protoporphyrin IX monomers [Fe(III)PPIX.OH] with recombinant HA2 and purified HRgpA, Kgp and RgpB gingipains. The HA2 domain reacted with Fe(III)PPIX.OH to form mu-oxo bishaem, the presence of which was confirmed by Fourier transform infrared spectroscopy. Both HRgpA and Kgp, but not RgpB, also mediated mu-oxo bishaem formation and aggregation. It is concluded that the Arg- and Lys-gingipains with HA2 haemagglutinin domains may play a crucial role in haem-pigment formation by converting Fe(III)PPIX.OH monomers into [Fe(III)PPIX]2O and promoting their aggregation.

Adhesins, Bacterial↗

PubMed2006

Inhibition of Porphyromonas gingivalis proteinases (gingipains) by chlorhexidine: synergistic effect of Zn(II).

BACKGROUND/AIMS: Gingipains, proteolytic enzymes produced by the periodontal pathogen Porphyromonas gingivalis, are regarded as virulence factors in the pathogenesis of periodontitis. Inhibition of gingipain activity therefore may have therapeutic potential, and it has been suggested that chlorhexidine may inhibit the activities of these enzymes. The purposes of the present study were to examine systematically the inhibitory effects of chlorhexidine on three purified gingipains and to determine the effect of Zn(II) on chlorhexidine inhibition. METHODS: The activities of lys-gingipain (Kgp) and two forms of arg-gingipain (RgpB and HRgpA) were measured in the presence of varying concentrations of chlorhexidine and with chlorhexidine supplemented with Zn(II). Inhibition constants (K(i)'s) were determined for chlorhexidine alone and in the presence of Zn(II). Fractional inhibitory constant indices were calculated to assess the synergy of the chlorhexidine-Zn(II) inhibition. RESULTS: RgpB, HRgpA, and Kgp were all inhibited by chlorhexidine with K(i)'s in the micromolar range. For RgpB and HRgpA, the inhibitory effects of chlorhexidine were enhanced 3-30-fold by Zn(II). The chlorhexidine-Zn(II) interaction was synergistic for inhibition of HRgpA and RgpB. For Kgp, the effect of Zn(II) on chlorhexidine inhibition was antagonistic. CONCLUSIONS: Chlorhexidine is an effective inhibitor of gingipains, and the inhibition of R-gingipains is enhanced by Zn(II). A mixture of chlorhexidine and Zn(II) may be useful as an adjunct in the treatment of periodontitis and in the post-treatment maintenance of periodontitis patients.

Adhesins, Bacterial↗

PubMed2003

Proteolysis of ICAM-1 on human oral epithelial cells by gingipains.

Cysteine proteinases (gingipains) from Porphyromonas gingivalis are considered key virulence factors of severe periodontitis and host immune evasion. Since expression of intercellular adhesion molecule-1 (ICAM-1) on gingival epithelium is indispensable in polymorphonuclear leukocyte (PMN) migration at the site of periodontitis, we examined the effects of gingipains on the expression of ICAM-1 on human oral epithelial cell lines (KB and HSC-2) by flow cytometry and Western blotting. We found that three purified forms of gingipains efficiently reduced ICAM-1 expression on the cells in a time- and dose-dependent manner. Gingipains reduced the expression on fixed cells and degraded the ICAM-1 in the cell membranes, indicating that the reduction resulted from direct proteolysis. They then disturbed the ICAM-1-dependent adhesion of PMNs to the cells. These results indicate that gingipains cleave ICAM-1 on oral epithelial cells, consequently disrupting PMN-oral epithelial cell interaction, and are involved in immune evasion by the bacterium in periodontal tissues.

Adhesins, Bacterial↗

PubMed2001

Inhibition of distant caspase homologues by natural caspase inhibitors.

Caspases play an important role in the ability of animal cells to kill themselves by apoptosis. Caspase activity is regulated in vivo by members of three distinct protease inhibitor families, two of which, baculovirus p35 and members of the inhibitor of apoptosis (IAP) family, are thought to be caspase specific. However, caspases are members of the clan of cysteine proteases designated CD, which also includes animal and plant legumains, and the bacterial proteases clostripain, gingipain-R and gingipain-K. Since these proteases have been proposed to have a common mechanism and evolutionary origin, we hypothesized that the caspase inhibitors may also regulate these other proteases. We tested this hypothesis by examining the effect of the natural caspase inhibitors on other members of protease clan CD. The IAP family proteins were found to have only a slight inhibitory effect on gingipain-R. The cowpox viral cytokine-response modifier A (CrmA) serpin had no effect on any of the proteases tested but a single point mutation of CrmA (Asp-->Lys) resulted in strong inhibition of gingipain-K. More substantial, with respect to the hypothesis, was the strong inhibition of gingipain-K by wild-type p35. The site in p35, required for inhibition of gingipain-K, was mapped to Lys94, seven residues C-terminal to the caspase inhibitory site. Our data indicate that the virally encoded caspase inhibitors have adopted a mechanism that allows them to regulate disparate members of clan CD proteases.

Amino Acid Sequence↗

PubMed2001

Activation of protease-activated receptors by gingipains from Porphyromonas gingivalis leads to platelet aggregation: a new trait in microbial pathogenicity.

The bacterium Porphyromonas gingivalis is a major etiologic agent in the pathogenesis of adult periodontitis in humans. Cysteine proteinases produced by this pathogen, termed gingipains, are considered to be important virulence factors. Among many other potentially deleterious activities, arginine-specific gingipains-R (RgpB and HRgpA) efficiently activate coagulation factors. To further expand knowledge of the interaction between gingipains and the clotting cascade, this study examined their effects on cellular components of the coagulation system. The enzymes induced an increase in intracellular calcium in human platelets at nanomolar concentrations and caused platelet aggregation with efficiency comparable to thrombin. Both effects were dependent on the proteolytic activity of the enzymes. Based on desensitization studies carried out with thrombin and peptide receptor agonists, and immunoinhibition experiments, gingipains-R appeared to be activating the protease-activated receptors, (PAR)-1 and -4, expressed on the surface of platelets. This was confirmed by the finding that HRgpA and RgpB potently activated PAR-1 and PAR-4 in transfected cells stably expressing these receptors. Cumulatively, the results indicate the existence of a novel pathway of host cell activation by bacterial proteinases through PAR cleavage. This mechanism not only represents a new trait in bacterial pathogenicity, but may also explain an emerging link between periodontitis and cardiovascular disease. (Blood. 2001;97:3790-3797)

Adhesins, Bacterial↗

PubMed2001

Loss of clumping factor B fibrinogen binding activity by Staphylococcus aureus involves cessation of transcription, shedding and cleavage by metalloprotease.

The fibrinogen-binding protein clumping factor B (ClfB) of Staphylococcus aureus is present on the surface of cells from the early exponential phase of growth in greater amounts than on cells from late exponential phase and is barely detectable on cells from stationary phase. Expression of a clfB-lacZ fusion indicated that transcription stopped before the end of exponential phase. Mutations in the global regulators agr and sar had no effect on clfB transcription. The loss of ClfB protein from cells in stationary phase was due to expression ending before cells stopped growing, combined with shedding of some of the protein into the growth medium and dilution of those molecules remaining on the cell surface during the two to three cell division events leading to stationary phase. Two forms of the protein occurred on the cell surface, the smaller of which was generated by loss of a domain from the N terminus. The proportion of the smaller form increased as the cultures grew. The metalloprotease aureolysin was shown to be responsible for cleavage of ClfB. Cleavage was inhibited by EDTA and o-phenanthroline and did not occur in an aureolysin-deficient mutant. Purified aureolysin promoted cleavage of cell surface-located ClfB as well as the recombinant A domain of ClfB. Cleavage was detected at two sites, one located between residues Ser(197) and Leu(198) and the other between Ala(199) and Val(200). The truncated form of ClfB did not bind fibrinogen.

Adhesins, Bacterial↗

PubMed2001

Activation of human prothrombin by arginine-specific cysteine proteinases (Gingipains R) from porphyromonas gingivalis.

The effect of 95- (HRgpA) and 50-kDa gingipain R (RgpB), arginine-specific cysteine proteinases from periodontopathogenic bacterium Porphyromonas gingivalis on human prothrombin activation was investigated. Each enzyme released thrombin from prothrombin in a dose- and time-dependent manner with the former enzyme, containing adhesion domains, being 17-fold more efficient than the single chain RgpB. A close correlation between the generation of fibrinogen clotting activity and amidolytic activity indicated that alpha-thrombin was produced by gingipains R, and this was confirmed by SDS-polyacrylamide gel electrophoresis, thrombin active site labeling, and amino-terminal sequence analysis of prothrombin digestion fragments. Significantly, the catalytic efficiency of HRgpA to generate thrombin (k(cat)/K(m) = 1.2 x 10(6) m(-)1 s(-)1) was 100-fold higher than that of RgpB (k(cat)/K(m) = 1.2 x 10(4) m(-)1 s(-)1). The superior prothrombinase activity of HRgpA over RgpB correlates with the fact that only the former enzyme was able to clot plasma, and kinetic data indicate that prothrombin activation can occur in vivo. At P. gingivalis-infected periodontitis sites HRgpA may be involved in the direct production of thrombin and, therefore, in the generation of prostaglandins and interleukin-1, both have been found to be associated with the development and progression of the disease. Furthermore, by taking into account that the P. gingivalis bacterium has been immunolocalized in carotid atherosclerotic plaques at thrombus formation sites (Chiu, B. (1999) Am. Heart J. 138, S534-S536), our results indicate that bacterial proteinases may potentially participate in the pathogenesis of cardiovascular disease associated with periodontitis.

Adhesins, Bacterial↗

PubMed2001

Activation of blood coagulation factor IX by gingipains R, arginine-specific cysteine proteinases from Porphyromonas gingivalis.

The effect of two arginine-specific cysteine proteinases (gingipains R) from Porphyromonas gingivalis, an aetiological factor of adult periodontitis, on the activation of human factor IX was investigated in the presence of ethylene glycol, an activity enhancer of activated factor IX (factor IXa), with the use of a fluorogenic oligopeptide substrate. Each gingipain R rapidly activated factor IX but the 95 kDa proteinase complex (HRgpA) that contains both haemagglutinin/adhesion and catalytic domains was 2.4-fold more efficient than the single-chain 50 kDa gingipain R (RgpB), which has only a catalytic domain. SDS/PAGE and N-terminal sequence analysis of factor IX digestion fragments indicated that, like all endogenous activators, gingipains R also produce factor IXabeta via an IXa intermediate. Significantly, phospholipids augmented the activation of factor IX by HRgpA but not by RgpB in a Ca(2+)-dependent manner. In the presence of both cofactors the kinetic efficiency of HRgpA to activate factor IX (k(cat)/K(m)=1.9x10(6) M(-1).s(-1)) was 8.5-fold higher than that of RgpB (k(cat)/K(m)=2.3x10(5) M(-1).s(-1)) and double that of the factor VIIa-tissue factor complex, but 8-fold lower than that for factor XIa. A comparison of the relative activation rates of factor IX, factor X and prothrombin directly in plasma by HRgpA suggests a significant contribution for factor IX conversion in blood coagulation induced by gingipains R. Taken together, gingipains R are the first-reported activators of factor IX of bacterial origin. By this effect they could be involved in the production of thrombin as well as the subsequent generation of prostaglandins and interleukin 1, all of which have been found to be associated with the development and progression of periodontitis.

Adhesins, Bacterial↗

PubMed2001

Functional characteristics of antibodies induced by Arg-gingipain (HRgpA) and Lys-gingipain (Kgp) from Porphyromonas gingivalis.

Arginine-specific gingipain (HRgpA) and lysine-specific gingipain (Kgp), enzymes produced by Porphyromonas gingivalis, may be candidates for an anti-P. gingivalis vaccine. The purpose of our study was to determine whether HRgpA and Kgp have opsonic target sites and whether these sites are available and accessible on intact P. gingivalis cells. Rabbits were used to generate polyclonal antibodies to both proteins. Animals were immunized and immunoglobulin G (IgG) fractions were isolated from preimmune and immune sera. Functional characteristics of the antibodies were assessed by determining antibody titers by enzyme-linked immunosorbent assay (ELISA), generating Western immunoblots, and measuring antibody enhancement of P. gingivalis opsonization, phagocytosis and killing by polymorphonuclear leukocytes (PMN) of intact cells of strains of P. gingivalis representative of the four serotypes. Strains studied included 33277 (serotype A), A7A1-28 (serotype B), W50 (serotype C) and 381 (serotype D). Both HRgpA and Kgp induced high titers of IgG antibody. Anti-HRgpA and anti-Kgp bound to both HRgpA and Kgp demonstrating a large proportion of shared antigenic epitopes. The two antibodies bound equally well to all four P. gingivalis serotypes with titers ranging from 77 to 205 ELISA units when compared to preimmune IgG set at 1 ELISA unit. The immunoblot patterns of binding of the two antibodies to HRgpA and Kgp and to sonicates of the four P. gingivalis serotypes were virtually identical. Both antibodies detected components in HRgpA at 27, 35 and 45 kDa and in Kgp at 27, 32, 35, 40 and 55 kDa. The antibodies also detected components at or near these same positions in addition to multiple high molecular mass components in the cell sonicates of P. gingivalis. Both proteins induced antibodies that significantly enhanced opsonization as assessed by chemiluminescence, with values ranging from 130 mV to 375 mV for anti-HRgpA IgG and from 240 mV to 475 mV for anti-Kgp IgG. Both antibodies significantly enhanced PMN-mediated bacterial killing of the four P. gingivalis serotypes, although the percentage of killing varied among the serotypes (24-81% for anti-HRgpA and 37-89% for anti-Kgp). Thus, both HRgpA and Kgp express opsonic target sites and induce high titers of antibodies that opsonize and enhance killing of all four serotypes of P. gingivalis. These two proteins appear to be potential candidate antigens for an anti-P. gingivalis vaccine.

Adhesins, Bacterial↗

PubMed2001

Inhibition of trypsin-like cysteine proteinases (gingipains) from Porphyromonas gingivalis by tetracycline and its analogues.

Extracellular cysteine proteinases, referred to as gingipains, are considered important virulence factors for Porphyromonas gingivalis, a bacterium recognized as a major etiologic agent of chronic periodontitis. We investigated the effect of tetracycline and its analogues, doxycycline and minocycline, on the enzymatic activities of gingipains. Tetracyclines at 100 microM totally inhibited the amidolytic activity of arginine-specific gingipains (HRgpA and RgpB). In contrast, inhibition of Kgp was less efficient and required a somewhat higher concentration of the antibiotic to achieve the same effect. Among tetracycline derivatives, the most potent gingipain inhibitor was doxycycline, followed by tetracycline and minocycline. RgpB was inhibited by doxycycline in an uncompetitive and reversible manner with a 50% inhibitory concentration of 3 microM. Significantly, inhibition was unaffected by calcium, excluding the chelating activity of tetracyclines as the mechanism of gingipain inactivation. In contrast, the inhibitory activities of the tetracyclines were reduced by cysteine, a reducing agent, suggesting an interference of the drug at the oxidative region with the catalytic system of the enzyme. Doxycycline, at 10 microM, significantly inhibited the RgpB-mediated production of vascular permeability-enhancing activity from human plasma, thus proving an effective inhibition of gingipain in vivo. These results indicate a new activity of tetracyclines as cysteine proteinase inhibitors and may explain the therapeutic efficiency of these antibiotics in the treatment of periodontitis.

Adhesins, Bacterial↗

PubMed2001

Mechanisms mediating Porphyromonas gingivalis gingipain RgpA-induced oral mucosa inflammation in vivo.

Suffusion of gingipain RgpA (GRgpA) elicited a significant concentration-dependent increase in the clearance of macromolecules from in situ hamster cheek pouch which was attenuated by NPC 17647, a selective bradykinin B(2) receptor antagonist. Leupeptin and a mixture of proteinase inhibitors also attenuated GRgpA-induced responses. These data indicate that GRgpA elicits plasma exudation from in situ oral mucosa in a catalytic site-dependent fashion by elaborating bradykinin.

Adhesins, Bacterial↗

PubMed2001

Salivary histatin 5 is an inhibitor of both host and bacterial enzymes implicated in periodontal disease.

One of the salient features of periodontitis and gingivitis is the increase in the levels of bacterial and host-derived proteolytic enzymes in oral inflammatory exudates. This study evaluated the potential of histatin 5, a 24-residue histidine-rich salivary antimicrobial protein, to inhibit these enzymes. Using biotinylated gelatin as a substrate, histatin 5 was found to inhibit the activity of the host matrix metalloproteinases MMP-2 and MMP-9 with 50% inhibitory concentrations (IC50s) of 0.57 and 0.25 microM, respectively. To localize the domain responsible for this inhibition, three peptides containing different regions of histatin 5 were synthesized and tested as inhibitors of MMP-9. Peptides comprising residues 1 to 14 and residues 4 to 15 of histatin 5 showed much lower inhibitory activities (IC50, 21.4 and 20.5 microM, respectively), while a peptide comprising residues 9 to 22 showed identical activity to histatin 5 against MMP-9. These results point to a functional domain localized in the C-terminal part of histatin 5. To evaluate the effect of histatin 5 on bacterial proteases, a detailed characterization of histatin 5 inhibition of gingipains from Porphyromonas gingivalis was carried out using purified Arg- and Lys-specific enzymes. Kinetic analysis of the inhibition of the Arg-gingipain revealed that histatin 5 is a competitive inhibitor, affecting only the Km with a K(i) of 15 microM. In contrast, inhibition of Lys-gingipain affected both the Km and Vmax, suggesting that both competitive and noncompetitive competitive processes underlie this inhibition. The inhibitory activity of histatin 5 against host and bacterial proteases at physiological concentrations points to a new potential biological function of histatin in the oral cavity.

Adhesins, Bacterial↗

PubMed2001

Arginine-specific protease from Porphyromonas gingivalis activates protease-activated receptors on human oral epithelial cells and induces interleukin-6 secretion.

Periodontitis is a chronic inflammatory disease affecting oral tissues. Oral epithelial cells represent the primary barrier against bacteria causing the disease. We examined the responses of such cells to an arginine-specific cysteine proteinase (RgpB) produced by a causative agent of periodontal disease, Porphyromonas gingivalis. This protease caused an intracellular calcium transient in an oral epithelial cell line (KB), which was dependent on its enzymatic activity. Since protease-activated receptors (PARs) might mediate such signaling, reverse transcription-PCR was used to characterize the range of these receptors expressed in the KB cells. The cells were found to express PAR-1, PAR-2, and PAR-3, but not PAR-4. In immunohistochemical studies, human gingival epithelial cells were found to express PAR-1, PAR-2, and PAR-3 on their surface, but not PAR-4, indicating that the cell line was an effective model for the in vivo situation. PAR-1 and PAR-2 expression was confirmed in intracellular calcium mobilization assays by treatment of the cells with the relevant receptor agonist peptides. Desensitization experiments strongly indicated that signaling of the effects of RgpB was occurring through PAR-1 and PAR-2. Studies with cells individually transfected with each of these two receptors confirmed that they were both activated by RgpB. Finally, it was shown that, in the oral epithelial cell line, PAR activation by the bacterial protease-stimulated secretion of interleukin-6. This induction of a powerful proinflammatory cytokine suggests a mechanism whereby cysteine proteases from P. gingivalis might mediate inflammatory events associated with periodontal disease on first contact with a primary barrier of cells.

Adhesins, Bacterial↗

PubMed2001

Degradation of host heme proteins by lysine- and arginine-specific cysteine proteinases (gingipains) of Porphyromonas gingivalis.

Porphyromonas gingivalis can use hemoglobin bound to haptoglobin and heme complexed to hemopexin as heme sources; however, the mechanism by which hemin is released from these proteins has not been defined. In the present study, using a variety of analytical methods, we demonstrate that lysine-specific cysteine proteinase of P. gingivalis (gingipain K, Kgp) can efficiently cleave hemoglobin, hemopexin, haptoglobin, and transferrin. Degradation of hemopexin and transferrin in human serum by Kgp was also detected; however, we did not observe extensive degradation of hemoglobin in serum by Kgp. Likewise the beta-chain of haptoglobin was partially protected from degradation by Kgp in a haptoglobin-hemoglobin complex. Arginine-specific gingipains (gingipains R) were also found to degrade hemopexin and transferrin in serum; however, this was observed only at relatively high concentrations of these enzymes. Growth of P. gingivalis strain A7436 in a minimal media with normal human serum as a source of heme correlated not only with the ability of the organism to degrade hemoglobin, haptoglobin, hemopexin, and transferrin but also with an increase in gingipain K and gingipain R activity. The ability of gingipain K to cleave hemoglobin, haptoglobin, and hemopexin may provide P. gingivalis with a usable source of heme for growth and may contribute to the proliferation of P. gingivalis within periodontal pockets in which erythrocytes are abundant.

Adhesins, Bacterial↗

PubMed2001

pH-regulated secretion of a glyceraldehyde-3-phosphate dehydrogenase from Streptococcus gordonii FSS2: purification, characterization, and cloning of the gene encoding this enzyme.

Streptococcus gordonii and other viridans streptococci (VS) are primary etiologic agents of infective endocarditis, despite being part of the normal oral microflora. Recently, a surface-bound glyceraldehyde-3-phosphate dehydrogenase (GAPDH) has been found on the cells of all tested streptococcal species, where it has been implicated as a virulence factor. In contrast, we observed that a soluble extracellular GAPDH was the major secreted protein from S. gordonii FSS2, an endocarditis strain. The biochemical properties and gene sequence of S. gordonii GAPDH are almost identical to those of other streptococcal GAPDHs. Growth at defined pHs showed that secretion of GAPDH is regulated by environmental pH. GAPDH was primarily surface-associated at growth pH 6.5 and shifted to > 90% secreted at growth pH 7.5. Others have identified S. gordonii promoters that are up-regulated by a pH shift similar to that experienced by organisms entering the blood stream (neutral) from the oral cavity (slightly acid). Analysis of our results suggests that secretion of GAPDH may be a similar adaptation by S. gordonii.

Adaptation, Physiological↗

PubMed2001

Arginine-specific cysteine proteinase from porphyromonas gingivalis as a convenient tool in protein chemistry.

RgpB, a cysteine proteinase produced by Porphyromonas gingivalis, exhibits proteolytic activity selectively directed against peptide bonds containing an arginine residue in the P1 position. Here we show that this enzyme can be used for very efficient and specific protein cleavage. RgpB is highly active even at high concentrations of denaturing agents, including urea (up to 6 M) and SDS (0.1%), both of them being commonly used for solubilization of insoluble proteins and peptides. Moreover, RgpB is able to digest polypeptide chains in buffers supplemented with 1% Triton X-100, 1% octyl or decylpyranoside, detergents employed for the enzymatic digestion of proteins transferred onto nitrocellulose membranes. These features render RgpB a suitable tool for use in protein chemistry.

Amino Acid Sequence↗

PubMed2000

Porphyromonas gingivalis DPP-7 represents a novel type of dipeptidylpeptidase.

A novel dipeptidylpeptidase (DPP-7) was purified from the membrane fraction of Porphyromonas gingivalis. This enzyme, with an apparent molecular mass of 76 kDa, has the specificity for both aliphatic and aromatic residues in the P1 position. Although it belongs to the serine class of peptidases, it does not resemble other known dipeptidylpeptidases. Interestingly, the amino acid sequence around the putative active site serine residue shows significant similarity to the C-terminal region of the Staphylococcus aureus V-8 endopeptidase. The genes encoding homologues of DPP-7 were found in genomes of Xylella fastidiosa, Shewanella putrefaciens, and P. gingivalis. It is likely that at least in P. gingivalis, DPP-7 and its homologue, in concert with other di- and tripeptidases, serve nutritional functions by providing dipeptides to this asaccharolytic bacterium.

Amino Acid Sequence↗