Western blotting analysis of heat shock proteins of Rickettsiales and other eubacteria

Heat shock proteins (Hsp) of four Rickettsia species, three Bartonella species, two Ehrlichia species, Orientia tsutsugamushi and seventeen other eubacterial species were characterized by the enhanced chemiluminescence Western blotting (WB) technique with antibodies raised against recombinant Hsp from Escherichia coli and purified GroES from R. typhi. Although E. coli DnaK and GroEL have epitopes that are highly conserved among the homologous proteins found in Rickettsia, Ehrlichia, O. tsutsugamushi, Bartonella and other Proteobacteria, anti-E. coli DnaK and GroEL monoclonal antibodies (Dasch et al. (1990) Ann. N.Y. Acad. Sci. 590, 352–369) recognize less conserved epitopes. In contrast, epitopes on E. coli DnaJ, GrpE and GroES are much less conserved since anti-E. coli DnaJ, GrpE and GroES polyclonal antibodies did not recognize DnaJ, GrpE or GroES homologues in Rickettsia, Bartonella, Orientia, Ehrlichia and Legionella. Polyclonal antiserum prepared against GroES from R. typhi reacted strongly with purified 10 kDa GroES peptide from Rickettsia and Bartonella, and strongly bound to proteins of varying electrophoretic mobility from Wolbachia, Legionella, Proteus and Shigella flexneri and more weakly to other GroES homologues including that found in E. coli. Consequently, commercially available anti-DnaJ, anti-GrpE and anti-GroES polyclonal antibodies and anti-DnaK monoclonal antibody raised against their respective recombinant E. coli Hsp are not suitable for detection and identification of homologues of these proteins in a wide range of eubacteria.