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Infect. Immun., Mar 1996, 952-958, Vol 64, No. 3
F Chandad, D Mayrand, D Grenier, D Hinode and C Mouton
To further investigate the relationship between fimbriae and the
hemagglutinating adhesin HA-Ag2 of Porphyromonas gingivalis, three
spontaneous mutants of the type strain ATCC 33277 were selected by a
hemadsorption procedure. They were characterized for hemagglutination,
trypsin-like and lectin-binding activities, and hydrophobicity and for the
presence of fimbriae. The presence of the 42-kDa (the fimbrilin subunit)
and the 43- and 49-kDa (the HA-Ag2 components) polypeptides was
investigated by immunoblotting using polyclonal and monoclonal antibodies
directed to fimbriae and to the hemagglutinating adhesin HA- Ag2. Cells
from two of the three mutants (M1 and M2) exhibited no or little
hemagglutination activity and very low trypsin-like activity and did not
show the 43- and 49-kDa polypeptides. Abnormal fimbriation in M1 was
deduced from the following observations of cells grown for 18 h: absence of
the 42-kDa polypeptide and of a 14-kDa polypeptide and no fimbriae visible
on electron micrographs. While the cells of mutant M2, irrespective of the
age of the culture, were found to lack the 43- and 49-kDa polypeptides and
hemagglutination activity, the supernatants of cultures grown for 72 h had
high hemagglutination and trypsin-like activities and revealed the presence
of the 42-, 43-, and 49-kDa polypeptides. This suggests that M2 may be
missing some molecules which anchor the components to the cell surface.
Mutant M3 showed levels of activities similar to those of the parental
strain but lacked the 43- kDa polypeptide. Other pleiotropic effects
observed for the mutants included loss of dark pigmentation and lower
hydrophobicity. The data from this study fuel an emerging consensus whereby
fimbriation, hemagglutination, and proteolytic activities, as well as other
functions in P. gingivalis, are intricate.
Copyright © 1996, American Society for Microbiology
Selection and phenotypic characterization of nonhemagglutinating mutants of Porphyromonas gingivalis
Groupe de Recherche en Ecologie Buccale, Faculte de Medecine Dentaire, Universite Laval, Quebec, Canada.
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