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Infection and Immunity, July 1999, p. 3248-3256, Vol. 67, No. 7
Department of Biochemistry, University of
Georgia, Athens, Georgia 30602,1
Department of Arthritis Biology, Novartis Pharmaceuticals,
Summit, New Jersey 07901,3 and Institute
of Molecular Biology, Jagiellonian University, Krakow,
Poland2
Received 29 January 1999/Returned for modification 23 March
1999/Accepted 7 April 1999
The initiation and progression of adult-onset periodontitis has
been associated with infection of the gingival sulcus by
Porphyromonas gingivalis. This organism utilizes a
multitude of virulence factors to evade host defenses as it
establishes itself as one of the predominant pathogens in periodontal
pockets. A feature common to many other oral pathogens is the
production of ammonia due to its protective effect during acidic
cleansing cycles in the mouth. Additionally, ammonia production by
P. gingivalis has been proposed as a virulence factor due
to its negative effects on neutrophil function. In this study, we
describe the first purification of a peptidylarginine
deiminase (PAD) from a prokaryote. PAD exhibits biochemical
characteristics and properties that suggest that it may be a
virulence agent. PAD deiminates the guanidino group of carboxyl-terminal arginine residues on a variety of peptides, including the vasoregulatory peptide-hormone bradykinin, to yield ammonia and a citrulline residue. The soluble protein has an apparent mass of 46 kDa, while the DNA sequence predicts a full-length protein
of 61.7 kDa. PAD is optimally active at 55°C, stable at low pH, and
shows the greatest activity above pH 9.0. Interestingly, in
the presence of stabilizing factors, PAD is resistant to limited proteolysis and retains significant activity after short-term boiling.
We propose that PAD, acting in concert with arginine-specific proteinases from P. gingivalis, promotes the growth of the
pathogen in the periodontal pocket, initially by enhancing its
survivability and then by assisting the organism in its circumvention
of host humoral defenses.
0019-9567/99/$04.00+0
Copyright © 1999, American Society for Microbiology. All rights reserved.
Purification, Characterization, and Sequence Analysis of a
Potential Virulence Factor from Porphyromonas gingivalis,
Peptidylarginine Deiminase
*
Corresponding author. Mailing address: Dept. of
Biochemistry and Molecular Biology, The University of Georgia, Athens,
GA 30602. Phone: (706) 542-1713. Fax: (706) 542-3719. E-mail:
jtravis{at}arches.uga.edu.
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