The heat shock response in Actinobacillus actinomycetemcomitans, a cap
nophilic Gram-negative bacterial species that is implicated in the dev
elopment of certain forms of periodontitis, was characterized. Differe
nt strains of A. actinomycetemcomitans were grown at 37, 42 and 48 deg
rees C in the presence of S-35-methionine. The bacterial cells were ly
sed, run on SDS-PAGE and subsequently blotted on nitrocellulose paper.
After autoradiography of the blots, several protein bands from the cu
ltures at 42 degrees C showed an increased intensity; major bands were
observed at 90, 70, and 60 kDa, but increased protein synthesis was a
lso detected at 54, 28 and 17 kDa. Nitrocellulose blots were also incu
bated with a panel of monoclonal and polyclonal antibodies directed to
epitopes on different heat shock proteins. Strong reactivity was foun
d with several antibodies at the position corresponding to a molecular
mass of 60 kDa. The protein is probably the GroEL homologue in A. act
inomycetemcomitans, a member of the 'common bacterial antigen' family.