INHIBITION OF HUMAN IMMUNODEFICIENCY VIRUS-1 REVERSE-TRANSCRIPTASE ACTIVITY BY RUBROMYCINS - COMPETITIVE INTERACTION AT THE TEMPLATE - PRIMER SITE

Abstract

Rubromycins, a class of quinone antibacterials, were discovered to selectively inhibit human immunodeficiency virus-1 (HIV-1) RNA-directed DNA polymerase (reverse transcriptase) (RT) activity more potently than cellular DNA polymerase .alpha.. .beta.- and .gamma.-rubromycin each inhibited equipotently HIV-1 RT and avian myeloblastosis virus RT, in a concentration-dependent manner, and were significantly weaker as inhibitors of calf thymus DNA polymerase .alpha.. These agents inhibited HIV-1 RT reversibly, were competitive with respect to template.cntdot.primer, and were noncompetitive with respect to TTP. Dixon analyses yielded HIV RT Ki values of 0.27 .+-. 0.014 and 0.13 .+-. 0.012 .mu.M for .beta.- and .gamma.-rubromycin, respectively. Similarly, using DNA polymerase .alpha., the Ki values were 25.1 .+-. 4.3 and 3.9 .+-. 0.6 .mu.M for .beta.- and .gamma.-rubromycin, respectively. Because these agents were toxic to noninfected human T lymphoid cells using concentrations at or above 6 .mu.M, HIV-1 infectivity studies were carried out at 0.8-6 .mu.M. At these concentrations, which are below the range expected to provide protection, no significant antiviral activity was observed. Although .beta.- and .gamma.-rubromycins did not possess sufficient HIV RT inhibitory potency or selectivity versus mammalian DNA polymerase to demonstrate antiviral activities, these studies support the hypothesis that specific molecules containing quinone functional groups can selectivity inhibit viral polymerase activities over cellular polymerase activities. In addition, these studies suggest that rubromycins may be lead structures for the development of more potent and selective agents.