Open AccessCharacterization of human T‐cell leukemia virus type I integrase expressed in Escherichia coli
Author(s) -
Müller Barbara,
Kräusslich HansGeorg
Publication year - 1999
Publication title -
european journal of biochemistry
Language(s) - English
Resource type - Journals
eISSN - 1432-1033
pISSN - 0014-2956
DOI - 10.1046/j.1432-1327.1999.00026.x
Subject(s) - integrase , escherichia coli , biology , cleavage (geology) , microbiology and biotechnology , virus , gene , provirus , virology , biochemistry , genome , paleontology , fracture (geology)
The C‐terminal part of the pol gene of the human T‐cell leukemia virus type I (HTLV‐I) is predicted to encode the integrase (IN) of the virus; however, this protein has not yet been detected in virions or infected cells. We expressed the putative IN from an infectious molecular clone of HTLV‐I in Escherichia coli . Comparison with protein resulting from coexpression of HTLV‐I protease (PR) and Pol in insect cells indicated that the bacterially expressed protein is identical with or very similar to IN released from a PR‐Pol precursor by proteolytic cleavage. HTLV‐I IN was purified from E. coli under native conditions. The protein behaved like a dimer in size‐exclusion chromatography. It carried out activities characteristic of retroviral IN with high efficiency, displaying a strong preference for U5‐derived vs. U3‐derived sequences in the processing and strand‐transfer reactions. In the disintegration reaction, HTLV‐I IN not only accepted the double‐stranded branched substrate corresponding to the product of a strand‐transfer reaction, but was also able to carry out a phosphoryl transfer on a branched molecule with a single‐stranded or a single adenosine overhang.