Characterization of Heat Shock Proteins from Periodontopathogenic Bacteria and Their Virulences

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Recently, considerable attention has been given to the potential roles of heat shock protein (HSP) of in inflammation and autoimmune diseases. In this study, we established the isolation procedure of HSP from periodontopathogenic bacteria and investigated the immunological characterization of them using the specific antibodies.The isolation procedure of HSPs from whole cells of Porphyromonas gingivalis, Actinobacillus actinomycetemcomitans and Bacteroides forsythus was performed by affinity chromatography on adenosine 5'-triphosphate-agarose followed by preparative polyacrylmide gel electrophoresis and could obtain the considerable amount of purified GroEL- and DnaK-like proteins. Also, these proteins could be successfully used to obtain rabbit sera which possessed high titer of antibodies and a very good specificities comparing to the commercial ones.By Western-immunoblotting, it found that the GroEL-like protein from P.gingivalis was localized in cytoplasm and the DnaK-like protein f … More rom P.gingivalis was localized in both cytoplasm and periplasm.Analysis of the N-terminal amino acid sequence of each DnaK-like protein from P.gingivalis and B.forsythus showed a high degree of homology with the DnaK protein from Escherichia coli.However, these two HSPs reacted very weakly with a commercial anti-DnaK polyclonal antibody by dot-blotting.GroEL-like proteins isolated P.gingivalis, A.actinomycetemcomitans and B.forsythus showed a high degree of homology of their N-terminal amino acid sequences. Polyclonal antibodies raised against each GroEL-like protein showed a high level of cross-reactivity. Reactivity of these antibodies against recombinant human HSP60 was weak.Our findings suggest that DnaK- and GroEL-like proteins from periodontopathogens are well conserved and that the GroEL-like protein resemble each other more closely. It is possible to suggest that HSPs from bacteria are important targets of the immune response, however, these anti-infectious immune response may shift from their own protection to pathogenesis by their molecular mimicry. Less