Certain retrovirus and retrotransposons display strong biases in the selection of host DNA sites for integration. To probe the possibility that simple tethering of the retroelement integrase protein to a target DNA site is sufficient to direct integration, the activities of a hybrid composed of human immunodeficiency virus 1 integrase and λ repressor were analyzed. In in vitro reactions containing several target DNAs, the λ repressor-integrase hybrid was found to direct integration selectively to targets containing λ operators. Addition of λ repressor blocked selective integration, indicating that binding to the operators was required. The λ repressor-integrase hybrid protein directed integration primarily to sites near the operators on the same face of the B-DNA helix, indicating that target DNA was probably captured by looping out the intervening sequences. Such hybrid integrase proteins may be useful for directing retroviral integration to specific sequences in vivo.
Bushman, F. D. (1994). Tethering human immunodeficiency virus 1 integrase to a DNA site directs integration to nearby sequences. Proceedings of the National Academy of Sciences of the United States of America, 91(20), 9233–9237. https://doi.org/10.1073/pnas.91.20.9233