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  • Title: Regulation of autoproteolysis of the HIV-1 and HIV-2 proteases with engineered amino acid substitutions.
    Author: Rosé JR, Salto R, Craik CS.
    Journal: J Biol Chem; 1993 Jun 05; 268(16):11939-45. PubMed ID: 8505318.
    Abstract:
    Autoproteolysis of the retroviral aspartyl proteases is a major obstacle to purification and analysis of these enzymes. A mutagenic approach to rendering autolytic cleavage sites less labile was applied to the primary cleavage site between Leu5 and Trp6 in human immunodeficiency virus-1 (HIV-1) protease. From predictions based on known substrates it was concluded that amino acids Lys or Ser in place of Gln at position 7 would prevent cleavage at the Leu5-Trp6 peptide bond, therefore stabilizing the protein. Autoproteolytic stability was enhanced at least 100-fold by these mutations. At longer time points the protease was degraded at secondary sites which contained adequate substrate sequences but were conformationally restricted. Conversely, a mutation in HIV-2 protease which changed Lys7 to Gln rendered the protein 3-fold less stable and shifted the position of the initial autoproteolytic cleavage from Phe3-Ser4 to Leu5-Trp6. The effects of these mutations demonstrate that small changes in protein sequence can have a major impact on their autoproteolytic stability. The work described here suggests a general method for stabilizing proteases and perhaps other recombinantly produced proteins to autolysis.
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