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Infection and Immunity, August 2003, p. 4742-4748, Vol. 71, No. 8
0019-9567/03/$08.00+0     DOI: 10.1128/IAI.71.8.4742-4748.2003
Copyright © 2003, American Society for Microbiology. All Rights Reserved.

Effect of Inactivation of the Arg- and/or Lys-Gingipain Gene on Selected Virulence and Physiological Properties of Porphyromonas gingivalis

Daniel Grenier,1* Sophie Roy,1 Fatiha Chandad,1 Pascale Plamondon,1 Masami Yoshioka,2 Koji Nakayama,3 and Denis Mayrand4

Groupe de Recherche en Écologie Buccale, Faculté de Médecine Dentaire,1 Faculté des Sciences et de Génie, Université Laval, Quebec City, Quebec, Canada,4 Department of Preventive Dentistry, School of Dentistry, The University of Tokushima, Tokushima,2 Department of Microbiology, School of Dentistry, Nagasaki University, Nagasaki, Japan3

Received 7 November 2002/ Returned for modification 29 January 2003/ Accepted 1 May 2003

Proteolytic enzymes produced by Porphyromonas gingivalis are thought to play critical roles in the pathogenesis of periodontitis. The aim of this study was to investigate the effect of gingipain cysteine proteinase gene inactivation on selected pathological and physiological functions of P. gingivalis. Our results showed that Arg- and Lys-gingipain activities are critical components for the efficient growth of P. gingivalis in human serum. However, when the serum was supplemented with peptides provided as pancreatic casein hydrolysate, the gingipains did not appear to be essential for growth. The effect of gingipain gene inactivation on the susceptibility of P. gingivalis to serum bactericidal activity was investigated using standardized human serum. The wild-type strain, P. gingivalis ATCC 33277, was largely unaffected by the bactericidal activity of human serum complement. On the other hand, mutants lacking Arg-gingipain A, Arg-gingipain B, or Lys-gingipain activity were susceptible to complement. Since gingipains are mostly located on the outer membrane of P. gingivalis, inactivation of the genes for these enzymes may modify cell surface properties. We showed that gingipain-deficient mutants differed in their capacities to assimilate radiolabeled amino acids, cause hemolysis, express adhesins, hemagglutinate, and form biofilms. Lastly, the gingipains, more specifically Arg-gingipains, were responsible for causing major cell damage to human gingival fibroblasts. In conclusion, our study indicated that, in addition to being critical in the pathogenic process, gingipains may play a variety of physiological roles in P. gingivalis, including controlling the expression and/or processing of virulence factors. Mutations in gingipain genes thus give rise to pleiotropic effects.


* Corresponding author. Mailing address: Groupe de Recherche en Écologie Buccale, Université Laval, Quebec City, Quebec, Canada G1K 7P4. Phone: (418) 656-7341. Fax: (418) 656-2861. E-mail: Daniel.Grenier{at}greb.ulaval.ca.

Editor: V. J. DiRita


Infection and Immunity, August 2003, p. 4742-4748, Vol. 71, No. 8
0019-9567/03/$08.00+0     DOI: 10.1128/IAI.71.8.4742-4748.2003
Copyright © 2003, American Society for Microbiology. All Rights Reserved.




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