Processing protease and reverse transcriptase from human immunodeficiency virus type I polyprotein in Escherichia coli

Expression of the human immunodeficiency virus type I pol open reading frame in Escherichia coli led to several protease-mediated processing steps of the pol precursor polyprotein. Accumulation of two polypeptides with molecular sizes of 64 and 52 kilodaltons, with which reverse transcriptase activity is associated, was observed. The protease moiety of the precursor polyprotein accumulated as a 10-kilodalton species as a result of two specific cleavages. Furthermore, a single-amino-acid substitution in the putative active site of protease totally abolished processing of the precursor polyprotein.