Irreversible inhibition of human immunodeficiency virus type 1 integrase by dicaffeoylquinic acids

Human immunodeficiency virus type 1 (HIV-1) and other retroviruses require integration of a double-stranded DNA copy of the RNA genome into the host c ell chromosome for productive infection. The viral enzyme, integrase, catal yzes the integration of retroviral DNA and represents an attractive target for developing antiretroviral agents. We identified several derivatives of dicaffeoylquinic acids (DCQAs) that inhibit HIV-1 replication in tissue cul ture and catalytic activities of HIV-1 integrase in vitro. The specific ste p at which DCQAs inhibit the integration in vitro and the mechanism of inhi bition were examined in the present study. Titration experiments with diffe rent concentrations of HIV-1 integrase or DNA substrate found that the effe ct of DCQAs was exerted on the enzyme and not the DNA. In addition to HIV-1 , DCQAs also inhibited the in vitro activities of MLV integrase and truncat ed variants of feline immunodeficiency virus integrase, suggesting that the se compounds interacted with the central core domain of integrase. The inhi bition on retroviral integrases was relatively specific, and DCQAs had no e ffect on several other DNA-modifying enzymes and phosphoryltransferases. Ki netic analysis and dialysis experiments showed that the inhibition of integ rase by DCQAs was irreversible. The inhibition did not require the presence of a divalent cation and was unaffected by preassembling integrase onto vi ral DNA. The results suggest that the irreversible inhibition by DCQAs on i ntegrase is directed toward conserved amino acid residues in the central co re domain during catalysis.