Purification and characterization of human T-cell leukemia virus type I protease produced in Escherichia coli.

Human T-cell leukemia virus type I (HTLV-I) protease has been purified to homogeneity from a strain of recombinant Escherichia coli. The protease was expressed as a larger precursor, which was autoprocessed to form a mature protease. Protein chemical analyses revealed the coding sequence of mature protease, which agreed with the putative sequence predicted from the sequence of bovine leukemia virus protease. The purified protease processed the natural substrate gag precursor (p53) to form gag p19 and gag p24. The protease activity was inhibited by pepstatin A. These results provide direct evidence that this protease belongs to the aspartic protease family and has an activity consistent with the protease in HTLV-I virion.