1
|
Taniguchi M, Ochiai A. Characterization and production of multifunctional cationic peptides derived from rice proteins. Biosci Biotechnol Biochem 2017; 81:634-650. [DOI: 10.1080/09168451.2016.1277944] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Abstract
Food proteins have been identified as a source of bioactive peptides. These peptides are inactive within the sequence of the parent protein and must be released during gastrointestinal digestion, fermentation, or food processing. Of bioactive peptides, multifunctional cationic peptides are more useful than other peptides that have specific activity in promotion of health and/or the treatment of diseases. We have identified and characterized cationic peptides from rice enzymes and proteins that possess multiple functions, including antimicrobial, endotoxin-neutralizing, arginine gingipain-inhibitory, and/or angiogenic activities. In particular, we have elucidated the contribution of cationic amino acids (arginine and lysine) in the peptides to their bioactivities. Further, we have discussed the critical parameters, particularly proteinase preparations and fractionation or purification, in the enzymatic hydrolysis process for producing bioactive peptides from food proteins. Using an ampholyte-free isoelectric focusing (autofocusing) technique as a tool for fractionation, we successfully prepared fractions containing cationic peptides with multiple functions.
Collapse
Affiliation(s)
- Masayuki Taniguchi
- Department of Materials Science and Technology, Graduate School of Science and Technology, Niigata University, Niigata, Japan
- Center for Transdisciplinary Research, Niigata University, Niigata, Japan
| | - Akihito Ochiai
- Department of Materials Science and Technology, Graduate School of Science and Technology, Niigata University, Niigata, Japan
| |
Collapse
|
2
|
Dashper SG, Mitchell HL, Seers CA, Gladman SL, Seemann T, Bulach DM, Chandry PS, Cross KJ, Cleal SM, Reynolds EC. Porphyromonas gingivalis Uses Specific Domain Rearrangements and Allelic Exchange to Generate Diversity in Surface Virulence Factors. Front Microbiol 2017; 8:48. [PMID: 28184216 PMCID: PMC5266723 DOI: 10.3389/fmicb.2017.00048] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2016] [Accepted: 01/06/2017] [Indexed: 12/13/2022] Open
Abstract
Porphyromonas gingivalis is a keystone pathogen of chronic periodontitis. The virulence of P. gingivalis is reported to be strain related and there are currently a number of strain typing schemes based on variation in capsular polysaccharide, the major and minor fimbriae and adhesin domains of Lys-gingipain (Kgp), amongst other surface proteins. P. gingivalis can exchange chromosomal DNA between strains by natural competence and conjugation. The aim of this study was to determine the genetic variability of P. gingivalis strains sourced from international locations over a 25-year period and to determine if variability in surface virulence factors has a phylogenetic basis. Whole genome sequencing was performed on 13 strains and comparison made to 10 previously sequenced strains. A single nucleotide polymorphism-based phylogenetic analysis demonstrated a shallow tri-lobed phylogeny. There was a high level of reticulation in the phylogenetic network, demonstrating extensive horizontal gene transfer between the strains. Two highly conserved variants of the catalytic domain of the major virulence factor the Kgp proteinase (KgpcatI and KgpcatII) were found. There were three variants of the fourth Kgp C-terminal cleaved adhesin domain. Specific variants of the cell surface proteins FimA, FimCDE, MfaI, RagAB, Tpr, and PrtT were also identified. The occurrence of all these variants in the P. gingivalis strains formed a mosaic that was not related to the SNP-based phylogeny. In conclusion P. gingivalis uses domain rearrangements and genetic exchange to generate diversity in specific surface virulence factors.
Collapse
Affiliation(s)
- Stuart G Dashper
- Oral Health Cooperative Research Centre, Melbourne Dental School, Bio21 Institute, University of Melbourne VIC, Australia
| | - Helen L Mitchell
- Oral Health Cooperative Research Centre, Melbourne Dental School, Bio21 Institute, University of Melbourne VIC, Australia
| | - Christine A Seers
- Oral Health Cooperative Research Centre, Melbourne Dental School, Bio21 Institute, University of Melbourne VIC, Australia
| | - Simon L Gladman
- Victorian Life Sciences Computation Initiative Carlton, VIC, Australia
| | - Torsten Seemann
- Victorian Life Sciences Computation Initiative Carlton, VIC, Australia
| | - Dieter M Bulach
- Victorian Life Sciences Computation Initiative Carlton, VIC, Australia
| | | | - Keith J Cross
- Oral Health Cooperative Research Centre, Melbourne Dental School, Bio21 Institute, University of Melbourne VIC, Australia
| | - Steven M Cleal
- Oral Health Cooperative Research Centre, Melbourne Dental School, Bio21 Institute, University of Melbourne VIC, Australia
| | - Eric C Reynolds
- Oral Health Cooperative Research Centre, Melbourne Dental School, Bio21 Institute, University of Melbourne VIC, Australia
| |
Collapse
|
3
|
Taniguchi M, Matsuhashi Y, Abe TK, Ishiyama Y, Saitoh E, Kato T, Ochiai A, Tanaka T. Contribution of cationic amino acids toward the inhibition of Arg-specific cysteine proteinase (Arg-gingipain) by the antimicrobial dodecapeptide, CL(14-25), from rice protein. Biopolymers 2016; 102:379-89. [PMID: 25046435 DOI: 10.1002/bip.22525] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2014] [Revised: 06/11/2014] [Accepted: 06/28/2014] [Indexed: 11/11/2022]
Abstract
CL(14-25), a dodecapeptide, exhibits antimicrobial activity against Porphyromonas gingivalis with the 50% growth-inhibitory concentration (IC50 ) value of 145 µM, and arginine-specific gingipain (Rgp)-inhibitory activity. Kinetic analysis revealed that CL(14-25) is a mixed-type inhibitor, with inhibition constants (Ki and Ki ' values) of 1.4 × 10(-6) M and 4.3 × 10(-6) M, respectively. To elucidate the contributions of four cationic amino acid residues at the N- and C-termini of CL(14-25) toward Rgp-inhibitory activity, we investigated the Rgp-inhibitory activities of truncated and alanine-substituted analogs of CL(14-25). Rgp-inhibitory activities significantly decreased by truncated analogs, CL(15-25) and CL(16-25), whereas those of CL(14-24) and CL(14-23) were almost as high as that of CL(14-25). Rgp-inhibitory activities of alanine-substituted analogs, CL(R14A) and CL(R14A, R15A) also significantly decreased, whereas those of CL(K25A) and CL(R24A, K25A) were higher than that of CL(14-25). These results suggest that the arginine residue at position 15 substantially contributes to the Rgp-inhibitory activity and that the arginine residue at position 14 plays important roles in exerting Rgp-inhibitory activity. In this study, we demonstrated that CL(K25A) was a potent, dual function, peptide inhibitor candidate, exhibiting Rgp-inhibitory activity with Ki and Ki ' of 9.6 × 10(-7) M and 1.9 × 10(-6) M, respectively, and antimicrobial activity against P. gingivalis with an IC50 value of 51 µM.
Collapse
Affiliation(s)
- Masayuki Taniguchi
- Department of Materials Science and Technology, Graduate School of Science and Technology, Niigata University, Niigata, 950-2181, Japan; Center for Transdisciplinary Research, Niigata University, Niigata, 950-2181, Japan
| | | | | | | | | | | | | | | |
Collapse
|
4
|
Inaba H, Tagashira M, Kanda T, Murakami Y, Amano A, Matsumoto-Nakano M. Apple- and Hop-Polyphenols Inhibit Porphyromonas gingivalis-Mediated Precursor of Matrix Metalloproteinase-9 Activation and Invasion of Oral Squamous Cell Carcinoma Cells. J Periodontol 2016; 87:1103-11. [PMID: 27177287 DOI: 10.1902/jop.2016.160047] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
BACKGROUND Recent epidemiologic studies have revealed a significant association between periodontitis and oral squamous cell carcinoma (OSCC). Furthermore, periodontitis is markedly associated with orodigestive cancer mortality, whereas Porphyromonas gingivalis (Pg) infection has been identified as a specific and potentially independent microbial factor related to increased risk of orodigestive cancer death. The authors previously reported that Pg induced the precursor form of matrix metalloproteinase-9 (proMMP-9) production via proteinase-activated receptor (PAR)-related pathways, after which proMMP-9 was activated by gingipains to enhance cellular invasion of SAS cells. In the present study, effects of selected polyphenols as inhibitors of cellular invasion caused by Pg gingipains in SAS cells are examined. METHODS OSCC cells were infected with Pg strains including gingipain mutants. To evaluate effects of inhibitors: 1) apple polyphenol (AP); 2) hop bract polyphenol (HBP); 3) high-molecular-weight fractions of HBP (HMW-HBP); 4) low-molecular-weight fractions of HBP (LMW-HBP); 5) epigallocatechin gallate (EGCg); 6) KYT-1 (Arg-gingipain inhibitor); and KYT-36 (Lys-gingipain inhibitor) in combination are used. PAR2 and PAR4 mRNA expressions are examined using real-time reverse transcription polymerase chain reaction, and signaling pathways are evaluated by western blotting analysis. RESULTS KYT-1/KYT-36, AP, HBP, and HMW-HBP significantly inhibited PAR2 and PAR4 mRNA expressions, proMMP-9 activation, and cellular invasion. Furthermore, AP, HBP, and HMW-HBP reduced activation of heat shock protein 27 and Ets1 and nuclear translocation of nuclear factor-kappa B, whereas EGCg and LMW-HBP did not. CONCLUSION These results suggest that AP, HBP, HMW-HBP are potent inhibitors of proMMP-9 activation and cellular invasion mediated with Pg in OSCC cells.
Collapse
Affiliation(s)
- Hiroaki Inaba
- Department of Pediatric Dentistry, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama, Japan
| | - Motoyuki Tagashira
- Research and Development-Production Headquarters, Asahi Breweries Limited, Ibaraki, Japan
| | - Tomomasa Kanda
- Research and Development-Production Headquarters, Asahi Breweries Limited, Ibaraki, Japan
| | - Yukitaka Murakami
- Department of Oral Microbiology, Asahi University School of Dentistry, Hozumi, Gifu, Japan
| | - Atsuo Amano
- Department of Preventive Dentistry, Osaka University Graduate School of Dentistry, Suita-Osaka, Japan
| | - Michiyo Matsumoto-Nakano
- Department of Pediatric Dentistry, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama, Japan
| |
Collapse
|
5
|
Olsen I, Potempa J. Strategies for the inhibition of gingipains for the potential treatment of periodontitis and associated systemic diseases. J Oral Microbiol 2014; 6:24800. [PMID: 25206939 PMCID: PMC4138498 DOI: 10.3402/jom.v6.24800] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2014] [Revised: 07/15/2014] [Accepted: 07/15/2014] [Indexed: 12/13/2022] Open
Abstract
Gingipains are the major virulence factors of Porphyromonas gingivalis, the main periodontopathogen. It is expected that inhibition of gingipain activity in vivo could prevent or slow down the progression of adult periodontitis. To date, several classes of gingipain inhibitors have been recognized. These include gingipain N-terminal prodomains, synthetic compounds, inhibitors from natural sources, antibiotics, antiseptics, antibodies, and bacteria. Several synthetic compounds are potent gingipain inhibitors but inhibit a broad spectrum of host proteases and have undesirable side effects. Synthetic compounds with high specificity for gingipains have unknown toxicity effects, making natural inhibitors more promising as therapeutic gingipain blockers. Cranberry and rice extracts interfere with gingipain activity and prevent the growth and biofilm formation of periodontopathogens. Although the ideal gingipain inhibitor has yet to be discovered, gingipain inhibition represents a novel approach to treat and prevent periodontitis. Gingipain inhibitors may also help treat systemic disorders that are associated with periodontitis, including cardiovascular disease, rheumatoid arthritis, aspiration pneumonia, pre-term birth, and low birth weight.
Collapse
Affiliation(s)
- Ingar Olsen
- Department of Oral Biology, Faculty of Dentistry, University of Oslo, Oslo, Norway
| | - Jan Potempa
- Department of Microbiology, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, Krakow, Poland ; Department of Oral Immunology and Infectious Disease, School of Dentistry, University of Louisville, Louisville, Kentucky, USA
| |
Collapse
|
6
|
Huq NL, Seers CA, Toh ECY, Dashper SG, Slakeski N, Zhang L, Ward BR, Meuric V, Chen D, Cross KJ, Reynolds EC. Propeptide-mediated inhibition of cognate gingipain proteinases. PLoS One 2013; 8:e65447. [PMID: 23762374 PMCID: PMC3677877 DOI: 10.1371/journal.pone.0065447] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2012] [Accepted: 04/24/2013] [Indexed: 12/31/2022] Open
Abstract
Porphyromonas gingivalis is a major pathogen associated with chronic periodontitis. The organism’s cell-surface cysteine proteinases, the Arg-specific proteinases (RgpA, RgpB) and the Lys-specific proteinase (Kgp), which are known as gingipains have been implicated as major virulence factors. All three gingipain precursors contain a propeptide of around 200 amino acids in length that is removed during maturation. The aim of this study was to characterize the inhibitory potential of the Kgp and RgpB propeptides against the mature cognate enzymes. Mature Kgp was obtained from P. gingivalis mutant ECR368, which produces a recombinant Kgp with an ABM1 motif deleted from the catalytic domain (rKgp) that enables the otherwise membrane bound enzyme to dissociate from adhesins and be released. Mature RgpB was obtained from P. gingivalis HG66. Recombinant propeptides of Kgp and RgpB were produced in Escherichia coli and purified using nickel-affinity chromatography. The Kgp and RgpB propeptides displayed non-competitive inhibition kinetics with Ki values of 2.04 µM and 12 nM, respectively. Both propeptides exhibited selectivity towards their cognate proteinase. The specificity of both propeptides was demonstrated by their inability to inhibit caspase-3, a closely related cysteine protease, and papain that also has a relatively long propeptide. Both propeptides at 100 mg/L caused a 50% reduction of P. gingivalis growth in a protein-based medium. In summary, this study demonstrates that gingipain propeptides are capable of inhibiting their mature cognate proteinases.
Collapse
Affiliation(s)
- N. Laila Huq
- Oral Health Cooperative Research Centre, Melbourne Dental School, Bio21 Institute of Molecular Science and Biotechnology, The University of Melbourne, Victoria, Australia
| | - Christine A. Seers
- Oral Health Cooperative Research Centre, Melbourne Dental School, Bio21 Institute of Molecular Science and Biotechnology, The University of Melbourne, Victoria, Australia
| | - Elena C. Y. Toh
- Oral Health Cooperative Research Centre, Melbourne Dental School, Bio21 Institute of Molecular Science and Biotechnology, The University of Melbourne, Victoria, Australia
| | - Stuart G. Dashper
- Oral Health Cooperative Research Centre, Melbourne Dental School, Bio21 Institute of Molecular Science and Biotechnology, The University of Melbourne, Victoria, Australia
| | - Nada Slakeski
- Oral Health Cooperative Research Centre, Melbourne Dental School, Bio21 Institute of Molecular Science and Biotechnology, The University of Melbourne, Victoria, Australia
| | - Lianyi Zhang
- Oral Health Cooperative Research Centre, Melbourne Dental School, Bio21 Institute of Molecular Science and Biotechnology, The University of Melbourne, Victoria, Australia
| | - Brent R. Ward
- Oral Health Cooperative Research Centre, Melbourne Dental School, Bio21 Institute of Molecular Science and Biotechnology, The University of Melbourne, Victoria, Australia
| | - Vincent Meuric
- Oral Health Cooperative Research Centre, Melbourne Dental School, Bio21 Institute of Molecular Science and Biotechnology, The University of Melbourne, Victoria, Australia
| | - Dina Chen
- Oral Health Cooperative Research Centre, Melbourne Dental School, Bio21 Institute of Molecular Science and Biotechnology, The University of Melbourne, Victoria, Australia
| | - Keith J. Cross
- Oral Health Cooperative Research Centre, Melbourne Dental School, Bio21 Institute of Molecular Science and Biotechnology, The University of Melbourne, Victoria, Australia
| | - Eric C. Reynolds
- Oral Health Cooperative Research Centre, Melbourne Dental School, Bio21 Institute of Molecular Science and Biotechnology, The University of Melbourne, Victoria, Australia
- * E-mail:
| |
Collapse
|
7
|
Streptococcus mutans biofilm disruption by κ-casein glycopeptide. J Dent 2013; 41:521-7. [DOI: 10.1016/j.jdent.2013.03.010] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2012] [Revised: 03/13/2013] [Accepted: 03/26/2013] [Indexed: 11/19/2022] Open
|
8
|
Toh EC, Dashper SG, Huq NL, Attard TJ, Cross KJ, Stanton DP, Reynolds EC. Inhibition of proteolytic activity of periodontal pathogens by casein-derived peptides. Int Dairy J 2012. [DOI: 10.1016/j.idairyj.2011.12.009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/14/2022]
|
9
|
Lactoferrin inhibits Porphyromonas gingivalis proteinases and has sustained biofilm inhibitory activity. Antimicrob Agents Chemother 2012; 56:1548-56. [PMID: 22214780 DOI: 10.1128/aac.05100-11] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Porphyromonas gingivalis is a bacterial pathogen associated with chronic periodontitis that results in destruction of the tooth's supporting tissues. The major virulence determinants of P. gingivalis are its cell surface Arg- and Lys-specific cysteine proteinases, RgpA/B and Kgp. Lactoferrin (LF), an 80-kDa iron-binding glycoprotein found in saliva and gingival crevicular fluid, is believed to play an important role in innate immunity. In this study, bovine milk LF displayed proteinase inhibitory activity against P. gingivalis whole cells, significantly inhibiting both Arg- and Lys-specific proteolytic activities. LF inhibited the Arg-specific activity of purified RgpB, which lacks adhesin domains, and also inhibited the same activity of the RgpA/Kgp proteinase-adhesin complexes in a time-dependent manner, with a first-order inactivation rate constant (k(inact)) of 0.023 min(-1) and an inhibitor affinity constant (K(I)) of 5.02 μM. LF inhibited P. gingivalis biofilm formation by >80% at concentrations above 0.625 μM. LF was relatively resistant to hydrolysis by P. gingivalis cells but was cleaved into two major polypeptides (53 and 33 kDa) at R(284) to S(285), as determined by in-source decay mass spectrometry; however, these polypeptides remained associated with each other and retained inhibitory activity. The biofilm inhibitory activity of LF against P. gingivalis was not attributed to direct antibacterial activity, as LF displayed little growth inhibitory activity against planktonic cells. As the known RgpA/B and Kgp inhibitor N-α-p-tosyl-l-lysine chloromethylketone also inhibited P. gingivalis biofilm formation, the antibiofilm effect of LF may at least in part be attributable to its antiproteinase activity.
Collapse
|
10
|
Vincents B, Guentsch A, Kostolowska D, von Pawel-Rammingen U, Eick S, Potempa J, Abrahamson M. Cleavage of IgG1 and IgG3 by gingipain K from Porphyromonas gingivalis may compromise host defense in progressive periodontitis. FASEB J 2011; 25:3741-50. [PMID: 21768393 PMCID: PMC3177567 DOI: 10.1096/fj.11-187799] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2011] [Accepted: 07/01/2011] [Indexed: 01/08/2023]
Abstract
Degradation of immunoglobulins is an effective strategy of bacteria to evade the immune system. We have tested whether human IgG is a substrate for gingipain K of Porphyromonas gingivalis and found that the enzyme can hydrolyze subclass 1 and 3 of human IgG. The heavy chain of IgG(1) was cleaved at a single site within the hinge region, generating Fab and Fc fragments. IgG(3) was also cleaved within the heavy chain, but at several sites around the CH2 region. Investigation of the enzyme kinetics of IgG proteolysis by gingipain K, using FPLC- and isothermal titration calorimetry-based assays followed by Hill plots, revealed non-Michaelis-Menten kinetics involving a mechanism of positive cooperativity. In ex vivo studies, it was shown that gingipain K retained its IgG hydrolyzing activity in human plasma despite the high content of natural protease inhibitors; that IgG(1) cleavage products were detected in gingival crevicular fluid samples from patients with severe periodontitis; and that gingipain K treatment of serum samples from patients with high antibody titers against P. gingivalis significantly hindered opsonin-dependent phagocytosis of clinical isolates of P. gingivalis by neutrophils. Altogether, these findings underline a biological function of gingipain K as an IgG protease of pathophysiological importance.
Collapse
Affiliation(s)
- Bjarne Vincents
- Department of Laboratory Medicine, Division of Clinical Chemistry and Pharmacology, Lund University, University Hospital, Lund, Sweden
| | - Arndt Guentsch
- Department of Conservative Dentistry, University Hospital of Jena, Jena, Germany
| | - Dominika Kostolowska
- Department of Microbiology, Faculty of Biochemistry, Biophysics, and Biotechnology, Jagiellonian University, Kraków, Poland
| | | | - Sigrun Eick
- Department of Periodontology, Laboratory of Oral Microbiology, University of Bern, Bern, Switzerland; and
| | - Jan Potempa
- Department of Microbiology, Faculty of Biochemistry, Biophysics, and Biotechnology, Jagiellonian University, Kraków, Poland
- University of Louisville Dental School, Center for Oral Health and Systemic Diseases, Louisville, Kentucky, USA
| | - Magnus Abrahamson
- Department of Laboratory Medicine, Division of Clinical Chemistry and Pharmacology, Lund University, University Hospital, Lund, Sweden
| |
Collapse
|
11
|
Skottrup PD, Leonard P, Kaczmarek JZ, Veillard F, Enghild JJ, O'Kennedy R, Sroka A, Clausen RP, Potempa J, Riise E. Diagnostic evaluation of a nanobody with picomolar affinity toward the protease RgpB from Porphyromonas gingivalis. Anal Biochem 2011; 415:158-67. [PMID: 21569755 DOI: 10.1016/j.ab.2011.04.015] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2011] [Revised: 04/05/2011] [Accepted: 04/11/2011] [Indexed: 12/23/2022]
Abstract
Porphyromonas gingivalis is one of the major periodontitis-causing pathogens. P. gingivalis secretes a group of proteases termed gingipains, and in this study we have used the RgpB gingipain as a biomarker for P. gingivalis. We constructed a naive camel nanobody library and used phage display to select one nanobody toward RgpB with picomolar affinity. The nanobody was used in an inhibition assay for detection of RgpB in buffer as well as in saliva. The nanobody was highly specific for RgpB given that it did not bind to the homologous gingipain HRgpA. This indicated the presence of a binding epitope within the immunoglobulin-like domain of RgpB. A subtractive inhibition assay was used to demonstrate that the nanobody could bind native RgpB in the context of intact cells. The nanobody bound exclusively to the P. gingivalis membrane-bound RgpB isoform (mt-RgpB) and to secreted soluble RgpB. Further cross-reactivity studies with P. gingivalis gingipain deletion mutants showed that the nanobody could discriminate between native RgpB and native Kgp and RgpA in complex bacterial samples. This study demonstrates that RgpB can be used as a specific biomarker for P. gingivalis detection and that the presented nanobody-based assay could supplement existing methods for P. gingivalis detection.
Collapse
Affiliation(s)
- Peter Durand Skottrup
- Department of Pharmacology and Pharmacotherapy, Faculty of Pharmaceutical Sciences, University of Copenhagen, DK-2100 Copenhagen, Denmark.
| | | | | | | | | | | | | | | | | | | |
Collapse
|