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Infect. Immun., Jul 1996, 2532-2539, Vol 64, No. 7
MA Curtis, J Aduse-Opoku, JM Slaney, M Rangarajan, V Booth, J Cridland and P Shepherd
This study was performed to characterize the antigen(s) recognized by a
panel of monoclonal antibodies (MAbs) produced to be specific for
Porphyromonas gingivalis whole cells which we had previously shown to bind
to epitopes recognized by sera from periodontitis patients. Preliminary
data had suggested that the arginine-specific proteases of P. gingivalis
(ArgI, ArgIA, and ArgIB) contained the antigenic determinants of four of
these antibodies (MAbs 1A1, 2B/H9, 7D5, and 3B1). The location of the
binding sites was examined with purified P. gingivalis enzymes and
recombinant regions of the ArgI polyprotein expressed by subclones of the
prpR1 gene in Escherichia coli XL-1 Blue cells. All four antibodies were
reactive with protein determinants within the beta subunit, a hemagglutinin
and/or adhesin component, of the ArgI dimer. MAb 1A1 strongly inhibited the
agglutination of human erythrocytes by P. gingivalis W50 culture
supernatant, suggesting that the binding site for this antibody contains
residues which are critical for the interaction with the erythrocyte
surface. The determinant for MAb 1A1 was examined further by construction
of a set of truncated forms of the beta component expressed as fusion
proteins with glutathione S-transferase at the N terminus. Analysis of
these constructs mapped the binding site for MAb 1A1 to PrpRI residues
G-907 to T-931, GVSPKVCKDV TVEGSNEFAP VQNLT. Western blot (immunoblot)
analysis of P. gingivalis whole-cell proteins demonstrated that MAb 1A1
reacts with several proteins in the Mr range of 20,000 to 120,000.
Furthermore, an oligonucleotide probe corresponding to the coding sequence
for the region of the ArgI beta component containing the MAb 1A1 binding
site hybridized to multiple bands on genomic digests of P. gingivalis DNA.
These data indicate that the MAb 1A1 epitope may be a component of a
binding domain common to multiple gene products of this organism and may
thus represent a functionally important target of the host's specific
immune response to P. gingivalis in periodontal disease.
Copyright © 1996, American Society for Microbiology
Characterization of an adherence and antigenic determinant of the ArgI protease of Porphyromonas gingivalis which is present on multiple gene products
Department of Oral Microbiology, Medical Research Council Molecular Pathogenesis Group, London, United Kingdom. M. A. Curtis@2mds.qmw.ac.uk
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