Subsite specificity of the proteinase from myeloblastosis associated virus

• Published in: FEBS letters 1991-04, Vol.282 (1), p.73-76
• Main Authors: Konvalinka, Jan, Blaha, Ivo, Skrabana, Rostislav, Sedlacek, Juraj, Pichova, Iva, Kapralek, Frantisek, Kostka, Vladimir, Strop, Petr
• Format: Article
• Language: English
• Subjects: 4-nitrophenylalanine. The amino acid residues surrounding the cleaved bond are depicted according to Schechter and Berger , i.e. P4-P3-P2-P1 ★ P1′-P2′-P3′-P4′ the scissile bond being indicated by an asterisk; AIDS/HIV; Amino Acid Sequence; Analytical, structural and metabolic biochemistry; Aspartic Acid Endopeptidases - metabolism; Avian Myeloblastosis Virus - enzymology; Biological and medical sciences; Chromogenic substrate; E t; Enzymes and enzyme inhibitors; Fundamental and applied biological sciences. Psychology; HIV-1 proteinase; Hydrogen-Ion Concentration; Hydrolases; k cat; Kinetics; MAV; Michaelis-Menten parameters; Molecular Sequence Data; myeloblastosis-associated virus; Nle; norleucine; Nph; phenylstatine; PheSta; proteinase; rate constant according to equation V max = k cat · E t; Retroviral proteinase; Spectrum Analysis; Subsite specificity; Substrate Specificity; total enzyme concentration
• ISSN: 0014-5793; 1873-3468
• DOI: 10.1016/0014-5793(91)80447-B

The subsite requirements of the aspartic proteinase from the mycloblastosis-associated virus (MAV) for the cleavage of peptide substrates were studied with a series of synthetic peptides of general structure Ala-Thr-P4-P3-P2-P1 ★ Nph-Val-Arg-Lys-Ala. The residues in positions P4, P3, P2 and P1 were varied and the kinetic parameters for the cleavage of substrates in 2.0 M NaCl were spectrophotometrically determined at pH 6.0 and 37°C. The acceptance of amino acid residues in particular subsites is similar to that observed with the human immunodeficiency virus type 1 (HIV-1) proteinase in our earlier studies on the same substrate series: hydrophobic or aromatic residues are preferable in P1 position, a broad variety of residues are acceptable in P3 whereas the residues occupying P2 plays the decisive role in the substrate cleavage as evidenced by its dramatic influence on both k cat and K m values. The most remarkable difference between the two enzymes was found in P3 and P4 subsites. In P3, the introduction of negatively charged glutamate increases the substrate binding by the MAV proteinase 12-fold and decreases binding by the HIV-1 proteinase. In P4, Pro in this series is a favourable residue for the MAV proteinase and is strongly inacceptable for HIV-1 the proteinase. The pH profile of the cleavage was studied with a chromogenic substrate and differences between HIV-1 and MAV proteinases are discussed.