Retroviral integrase functions as a multimer and can turn over catalytically

• Published in: The Journal of biological chemistry Vol. 267; no. 23; pp. 16037 - 16040
• Main Authors: JONES, K. S, COLEMAN, J, MERKEL, G. W, LAUE, T. M, SKALKA, A. M
• Format: Journal Article
• Language: English
• Published: Bethesda, MD American Society for Biochemistry and Molecular Biology 15.08.1992
• Subjects: Analytical, structural and metabolic biochemistry; Animals; Avian Sarcoma Viruses - enzymology; Avian Sarcoma Viruses - genetics; Avian Sarcoma Viruses - isolation & purification; Biological and medical sciences; Cells, Cultured; DNA Nucleotidyltransferases - metabolism; DNA, Viral - genetics; DNA, Viral - metabolism; Enzymes and enzyme inhibitors; Fundamental and applied biological sciences. Psychology; Integrases; Kinetics; Macromolecular Substances; Miscellaneous; Models, Biological; Molecular Weight; Rous sarcoma virus; Virus Integration; Virus; Oncovirinae; Integration; Oligomerization; Enzymatic activity; Enzyme; Type C oncovirus; Retroviridae; Rous sarcoma virus; Kinetics; Sedimentation equilibrium
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1016/S0021-9258(18)41960-6

A number of studies have demonstrated that the retroviral protein integrase (IN) alone is sufficient to carry out two discrete steps required for retroviral integration: the endonucleolytic processing of viral DNA ends and the cleavage and joining of host DNA to the processed viral DNA termini. Little is known about the biochemical and biophysical mechanisms involved in these reactions. Here, we employ in vitro assays of Rous sarcoma virus IN to demonstrate for the first time that IN is capable of multiple turnover in both the processing and joining reactions. The turnover number calculated for the processing reaction is 0.26 cleavages/min/mol of IN. Our steady state kinetic studies indicate that both the processing and joining activities require a multimeric form of IN. Ultracentrifugation analyses reveal a substrate-independent reversible equilibrium among the monomeric, dimeric, and tetrameric forms of this protein. From these results we conclude that the minimal functional unit for both the processing and joining of each viral DNA end is an IN dimer.