title: HIV-1 RT enhances the activity of a tethered dimer of HIV-1 proteinase.
abstract: HIV-1 reverse transcriptase (RT) can specifically enhance HIV-1 proteinase activity in vitro and in eukaryotic cells (1). To determine if the effect of RT on proteinase activity was due to changes in the equilibrium dimerization constant of the proteinase or the stability of the proteinase dimer, we studied the effect of RT on a genetically engineered covalent dimer (tethered dimer) of the proteinase. RT was found to increase the activity of the tethered dimer independent of pH and ionic strength. The effect of RT on the kinetic constants (Km and kcat) of the wild type HIV-1 proteinase and its tethered dimer were also determined. These results show that RT can increase the enzymatic catalytic efficiency and substrate affinity of the proteinase, by a mechanism independent of promoting dimer formation.
authors.affiliation: Microbiology and Tumorbiology Center, MTC, Karolinska Institute, Stockholm, Sweden.
authors.forename: L
authors.initials: L
authors.lastname: Goobar-Larsson
authors.forename: P T
authors.initials: PT
authors.lastname: Larsson
authors.forename: C
authors.initials: C
authors.lastname: Debouck
authors.forename: E M
authors.initials: EM
authors.lastname: Towler
mesh_terms: D000595:Amino Acid Sequence; D016333:HIV Protease / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D054303:HIV Reverse Transcriptase; D015497:HIV-1 / Q000201:enzymology*; D006863:Hydrogen-Ion Concentration; D066298:In Vitro Techniques; D007700:Kinetics; D008969:Molecular Sequence Data; D009842:Oligopeptides / Q000737:chemistry; D009994:Osmolar Concentration; D011487:Protein Conformation; D015202:Protein Engineering; D012194:RNA-Directed DNA Polymerase / Q000378:metabolism*; D013379:Substrate Specificity
chemical_list: D009842:Oligopeptides; C092837:seryl-glutaminyl-asparaginyl-tyrosyl-prolyl-isoleucyl-valyl-glutamine; D054303:HIV Reverse Transcriptase; D012194:RNA-Directed DNA Polymerase; D016333:HIV Protease