ESCAPE MUTANTS OF HIV-1 PROTEINASE - ENZYMATIC EFFICIENCY AND SUSCEPTIBILITY TO INHIBITION

Genes encoding a number of mutants of HIV-1 proteinase were sub-cloned and expressed in E. coli. The proteinases containing mutations of sin gle residues (e.g., G48V, V82F, I84V and L90M) were purified and their catalytic efficiencies relative to that of wild-type proteinase were examined using a polyprotein (recombinant HIV-1 gag) substrate and sev eral series of synthetic peptides based on the -Hydrophobic Hydrophob ic-, -Aromatic Pro- and pseudo-symmetrical types of cleavage junction . The L90M proteinase showed only small changes, whereas the activity of the other mutant enzymes was compromised more severely, particularl y towards substrates of the -Aromatic Pro- and pseudo-symmetrical typ es The susceptibility of the mutants and the wild-type proteinase to i nhibition by eleven different compounds was compared. The L90M protein ase again showed only marginal changes in its susceptibility to all ex cept one of the inhibitors examined. The K-i values determined for one inhibitor (Ro31-8959) showed that its potency towards the V82F, L90M, I84V and G48V mutant proteinases respectively was 2-, 3-, 17- and 27- fold less than against the wild-type proteinase. Several of the other inhibitors examined form a systematic series with Ro31-8959. The inhib ition constants derived with these and a number of other inhibitors, i ncluding ABT-538 and L-735,524, are used in conjunction with the data on enzymic efficiency to assess whether each mutation in the proteinas e confers an advantage for viral replication in the presence of any gi ven inhibitor.