Localization of heat shock proteins in clinical Actinobacillus actinomycetemcomitans strains and their effects on epithelial cell proliferation

Actinobacillus actinomycetemcomitans is an important pathogen in periodonti tis. In the present study we localized the GroEL- and DnaK-like heat shock proteins (Hsp) in subcellular fractions of 12 A. actiizor??vcetemconlitans strains of various clinical origin and compared their effects on periodonta l epithelial cell proliferation and viability. In all strains, GroEL-like p rotein was found in the membrane, cytoplasm, and periplasm, whereas DnaK-li ke protein was present in the cytoplasm and periplasm. No correlation was o bserved between the Hsp expression and the serotype or origin of A. actinom ycetemocomitans strains. The bacterial membrane fractions that expressed th e GroEL-Iike protein moderately or strongly induced epithelial cell prolife ration more strongly than strains that expressed the protein weakly. The re sults suggest that GroEL-like Hsp may play a role in the virulence of A. ac tinomycetemcomitans by increasing epithelial proliferation. (C) 2000 Federa tion of European Microbiological Societies. Published by Elsevier Science B .V. All rights reserved.