Casein kinase II (CK-II)-mediated stimulation of HIV-1 reverse transcriptase activity and characterization of selective inhibitors in vitro

The physiological significance of the casein kinase II (CK-II)-mediated pho sphorylation of human immunodeficiency virus type 1 (HIV-1) reverse transcr iptase (RT) on its three enzymatic activities [RNA-dependent DNA polymerase (RDDP), DNA-dependent DNA polymerase (DDDP) and ribonuclease Ii (RNase H)] was investigated in vitro. It was found that (i) the purified recombinant RT (rRT) functioned as an effective phosphate acceptor for CK-II; (ii) the RDDP, DDDP and RNase H activity of rRT was stimulated about 2.8-, 4.1- and 3.9-fold, respectively, after full phosphorylation by CK-II; and (iii) this stimulation was selectively inhibited by potent CK-II inhibitors, such as neocarzinostatin-chromophore (NCS-chrom) and three polyphenol-containing an ti-oxidant compounds [quercetin, epigallocatechin gallate (EGCG) and 8-chlo ro-3',4',5,7-tetrahydroxyisoflavone (8C-3',4',5,7-THI)]. These results sugg est that (i) CK-II may be responsible for activation of RT in HIV-1-infecte d cells; and (ii) the selective inhibition of CK-II-mediated activation of HIV-1 RT by potent CK-II inhibitors may be involved in the mechanism of the ir anti-HIV-1 effects at the cellular level.