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Journal of Virology, September 2007, p. 10037-10046, Vol. 81, No. 18
0022-538X/07/$08.00+0     doi:10.1128/JVI.00519-07
Copyright © 2007, American Society for Microbiology. All Rights Reserved.

Molecular Mechanisms by Which Human Immunodeficiency Virus Type 1 Integrase Stimulates the Early Steps of Reverse Transcription{triangledown}

Charles W. Dobard, Marisa S. Briones, and Samson A. Chow*

Department of Molecular and Medical Pharmacology, Molecular Biology Institute, and UCLA AIDS Institute, UCLA School of Medicine, Los Angeles, California 90095

Received 12 March 2007/ Accepted 29 June 2007

Reverse transcriptase (RT) and integrase (IN) are two essential enzymes that play a critical role in synthesis and integration of the retroviral cDNA, respectively. For human immunodeficiency virus type 1 (HIV-1), RT and IN physically interact and certain mutations and deletions of IN result in viruses defective in early steps of reverse transcription. However, the mechanism by which IN affects reverse transcription is not understood. We used a cell-free reverse transcription assay with different primers and compositions of deoxynucleoside triphosphates to differentially monitor the effect of IN on the initiation and elongation modes of reverse transcription. During the initiation mode, addition of IN stimulated RT-catalyzed reverse transcription by fourfold. The stimulation was specific to IN and could not be detected when the full-length IN was replaced with truncated IN derivatives. The IN-stimulated initiation was also restricted to the template-primer complex formed using tRNA3Lys or short RNA oligonucleotides as the primer and not those formed using DNA oligonucleotides as the primer. Addition of IN also produced a threefold stimulation during the elongation mode, which was not primer dependent. The stimulation of both initiation and elongation by IN was retained in the presence of an RT trap. Furthermore, IN had no effect on steps at or before template-primer annealing, including packaging of viral genomic RNA and tRNA3Lys. Taken together, our results showed that IN acts at early steps of reverse transcription by increasing the processivity of RT and suppressing the formation of the pause products.

* Corresponding author. Mailing address: Department of Molecular and Medical Pharmacology, UCLA School of Medicine, Los Angeles, CA 90095. Phone: (310) 825-9600. Fax: (310) 825-6267. E-mail: schow{at}mednet.ucla.edu

{triangledown} Published ahead of print on 11 July 2007.

Journal of Virology, September 2007, p. 10037-10046, Vol. 81, No. 18
0022-538X/07/$08.00+0     doi:10.1128/JVI.00519-07
Copyright © 2007, American Society for Microbiology. All Rights Reserved.



This article has been cited by other articles:

  • Wilkinson, T. A., Januszyk, K., Phillips, M. L., Tekeste, S. S., Zhang, M., Miller, J. T., Le Grice, S. F. J., Clubb, R. T., Chow, S. A. (2009). Identifying and Characterizing a Functional HIV-1 Reverse Transcriptase-binding Site on Integrase. J. Biol. Chem. 284: 7931-7939 [Abstract] [Full Text]  


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