Biochemical characterization of recombinant equine infectious anemia virus integrase.

The integrase from equine infectious anemia virus (ELAV) was expressed in Escherichia coli as a polyhistidine fusion protein. The protein was purified under native and denaturing conditions using one-step nickel-affinity chromatography. The purified denatured protein was refolded in the presence of detergent. In vitro 3' processing and DNA strand transfer activities were analyzed under Mg(2+)- and Mn(2+)-dependent reaction conditions. Both protein preparations were similarly active. Only one viral DNA end was efficiently integrated during Mn(2+)-and Mg(2+)-dependent DNA strand transfer. Water was the predominant nucleophile for Mg(2+)- and Mn(2+)-dependent 3' processing activity. The results underscore functional similarities between EIAV integrase and the previously characterized HIV-1 enzyme.