Fig. 3

Cloning of PSF in bacterial expression system vector and in vitro IN activity assay. a The amplified PSF PCR product was digested with Kpn1 and Sac1 restriction enzyme and ligated with pPROEX-HTC bacterial expression vector. b Purified fractions of PSF by Nickel-NTA affinity chromatography. c 3′ processing assay was performed using IN (250 nM) and PSF and 0.5 pmol of radiolabeled oligos. PSF concentration varied from 0.1, 0.2, 0.5, 1 µM in the lanes and incubated for 30 min. Lane 1 contains only IN and oligos. d Strand transfer activity was done using oligos mentioned in method section. The lanes contains IN (250 nM) and PSF from 0.1 to 1 µM but incubated at 1 and 2 h respectively. Lane 1 contains only IN (250 nM) and oligos. The reaction products were analyzed by electrophoresis on 15% polyacrylamide gels with 8 M urea in Tris borate—EDTA, pH 7.6, and autoradiographed