Characterization of the functional properties of the 70-kDa protein of Mycobacterium bovis

A number of mycobacterial proteins have been shown to induce strong humoral and cellular immune responses, including the 70-kDa antigen (p70) of Mycobacterium leprae and Mycobacterium bovis. On the basis of sequence homology and an ATP binding ability, p70 has previously been tentatively allocated to the 70-kDa family of heat shock proteins (hsp70). We have purified the M. bovis p70 antigen and described ATPase and Ca(2+)-dependent autophosphorylating activities. These co-purified with p70 on gel chromatography and were up-regulated by native proteins and down-regulated by peptides. Inhibitory peptides were shown to bind p70. These data imply close functional similarities of mycobacterial p70 to other members of the hsp70 family, the Escherichia coli homologue dnaK in particular.