Heat shock response in Actinobacillus actinomycetemcomitans

Abstract The heat shock response in Actinobacillus actinomycetemcomitans , a capnophilic Gram-negative bacterial species that is implicated in the development of certain forms of periodontitis, was characterized. Different strains of A. actinomycetemcomitans were grown at 37, 42 and 48°C in the presence of ³⁵S-methionine. The bacterial cells were lysed, run on SDS-PAGE and subsequently blotted on nitrocellulose paper. After autoradiography of the blots, several protein bands from the cultures at 42°C showed an increased intensity; major bands were observed at 90, 70, and 60 kDa, but increased protein synthesis was also detected at 54, 28 and 17 kDa. Nitrocellulose blots were also incubated with a panel of monoclonal and polyclonal antibodies directed to epitopes on different heat shock proteins. Strong reactivity was found with several antibodies at the position corresponding to a molecular mass of 60 kDa. The protein is probably the GroEL homologue in A. actinomycetemcomitans , a member of the ‘common bacterial antigen’ family.