Biochemical characterization of recombinant HIV-1 reverse transcriptase (rRT) as a glycyrrhizin-binding protein and the CK-II-mediated stimulation ofrRT activity potently inhibited by glycyrrhetinic acid derivative

By means of successive Mono Q and glycyrrhizin (CL)-affinity column chromat ograph (HPLC), recombinant HIV-1 RT (rRT) was purified to apparent homogene ity from the Superdex 200 pg fraction of the crude protein extract of E. co li BL21 transfected with pET 21a(S)/HIV-1 PR-RT, It was found that (i) rRT functioned as an effective phosphate acceptor for recombinant human casein kinase II (rhCK-II) in vitro; (ii) this phosphorylation was inhibited by an ti-HIV-1 substances [a glycyrrhetinic acid derivative (oGA) and quercetin] and a high dose (100 mu M) Of GL; (iii) RNA-dependent DNA polymerase (RDDP) activity was stimulated about 2.5-fold after full phosphorylation of rRT b y rhCK-II; and (iv) oGA as well as NCS-chromophore effectively prevented th e CK-II-mediated stimulation of RDDP activity. These results suggest that t he anti-HIV-1 effect of oGA may be involved in the selective inhibition of the CK-II-mediated stimulation of HIV-1 RT at the cellular level.