We previously reported an association between elevated serum antibody titer
s to the 90-kDa human heat shock protein (Hsp90), periodontal health and co
lonization by Porphyromonas gingivalis. In this study, we examined the cell
ular localization of the Hsp90 homologue of P. gingivalis. Cultures of P. g
ingivalis were heat-stressed (45 degrees C) and examined for localization o
f the Hsp90 homologue. Heat stress induced a 4-5-fold increase in anti-Hsp9
0 antibody reactivity over that of the unstressed controls. Western blot an
alysis revealed two bands (44 and 68 kDa) that reacted with anti-Hsp90 anti
bodies. The 68-kDa band was heat-inducible, while the 44-kDa band was not.
Immunogold staining revealed that the Hsp90 homologue localized principally
to the membrane and extracellular vesicles. Subcellular fractionation conf
irmed that the Hsp90 homologue was primarily membrane-associated. (C) 1999
Federation of European Microbiological Societies. Published by Elsevier Sci
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