Substitution mutations of the highly conserved arginine 87 of HIV-1 protease result in loss of proteolytic activity

Abstract

The 297bp gene coding for the HIV-1 protease was chemically synthesized and expressed in E. coli (1). Single amino acid substitutions (Arg 87 -> Lys; Arg 87 -> Glu) were introduced in the C-terminally located conserved region GlyArgAsn of the protease gene in the wild-type clone. The products of the mutant and the wild-type clones were expressed at approximately similar levels at 30 minutes of induction but the mutant protease proteins accumulated as a function of time of induction unlike the wild-type protease which declined after 60 minutes. The mutants were completely devoid of proteolytic activity as determined in assays employing as substrates a synthetic nonapeptide and a gag related recombinant polyprotein.