HIV-1 RT ENHANCES THE ACTIVITY OF A TETHERED DIMER OF HIV-1 PROTEINASE

HIV-1 reverse transcriptase (RT) can specifically enhance HIV-1 protei nase activity in vitro and in eukaryotic cells (1). To determine if th e effect of RT on proteinase activity was due to changes in the equili brium dimerization constant of the proteinase or the stability of the proteinase dimer, we studied the effect of RT on a genetically enginee red covalent dimer (tethered dimer) of the proteinase. RT was found to increase the activity of the tethered dimer independent of pH and ion ic strength. The effect of RT on the kinetic constants (K-M and k(cat) ) of the wild type HIV-1 proteinase and its tethered dimer were also d etermined. These results show that RT can increase the enzymatic catal ytic efficiency and substrate affinity of the proteinase, by a mechani sm independent of promoting dimer formation. (C) 1996 Academic Press, Inc.