CATALYTIC ACTIVITIES OF THE HUMAN T-CELL LEUKEMIA-VIRUS TYPE-II INTEGRASE

Despite the widespread nature of HTLV-II in New World populations and intravenous drug users, the enzymatic activities of the pol genes have not been reported. To ascertain the activity of the HTLV-IIG12 integr ase (IN), the coding region was isolated and the encoded protein was p urified, using nickel-affinity chromatography, to greater than 90% hom ogeneity. HTLV-IIG12 IN proved active on HTLV-IIG12 and HIV-1 integrat ion and disintegration substrates. Distinct differences in requirement s for enzyme concentration for 3'-processing, strand-transfer, and dis integration reactions were observed. Catalysis of integration reaction s occurred in the presence of either Mn2+ or Mg2+, although strand-tra nsfer activity preferred Mn2+ In comparison, HTLV-IIG12 IN catalyzed d isintegration reactions with almost 10-fold less protein, was not sele ctive for Mn2+ or Mg2+, and tolerated higher NaCl concentrations than integration. HTLV-IIG12 IN was unable to catalyze the ''splicing'' rea ction, which suggests that this may not be an activity ubiquitous to a ll retroviral integrases. (C) 1996 Academic Press, Inc.