AEGiS-11IAC: Interaction of HIV-1 integrase with host factor Ini l (integrase interactor-1).

11th International AIDS Conference

Vancouver, British Columbia — July 7-12, 1996

Interaction of HIV-1 integrase with host factor Ini l (integrase interactor-1).

Int Conf AIDS 1996 Jul 7-12; 11:216 (abstract no. Th.A.380)
Morozov A, Cheng G, Marmon S, Kalpana GV; Albert Einstein College of Medicine, Bronx, NY, USA. Fax: 718-430-8778. E-mail: kalpana@ae.com.yu.edu.

OBJECTIVES: To understand the role of host factors in HIV-1 integration. Previously we identified a novel host factor Inil (Integrase interactor-1) that specifically binds to HIV-1 integrase (IN) and stimulates its joining activity. Inil is a human transcription factor involved in reorganizing the chromatin, is part of the mammalian SNF/SWI complex, and also part of RNA Pol II holoenzyme complex. Inil may be involved in targeting integration into open chromatin and may ensure proviral transcription by its association with the holoenzyme complex. To better understand the function of Inil we have begun to i) dissect the structural properties of IN-Inil interaction; and ii) identify the cellular proteins that interact with Inil.

METHODS: Two-hybrid system was used to identify: i) oligomerization of Inil with itself; ii) minimal domain of Inil involved in binding to IN; and iii) cellular proteins that bind to Inil. For all these analyses, full length clones of Inil or IN were fused to LexA DNA binding domain (LexADB), and either a full length Inil or nested deletion libraries of Inil or a human cDNA library were fused to GAL4 activation domain (GAL4AD). Combinations of LexADB and GAL4AC fusion proteins were co-expressed in yeast and their ability to transactivate lacZ reporter gene was determined. Percentages of blue colonies were scored, the plasmids were rescued from positive blue transformants and subjected to sequence analysis. Results and conclusions: We found that Inil is an oligomer like IN. Sequence analysis of Inil deletion clones indicated that a highly conserved stretch of amino acids with one of the two imperfect repeat motif is necessary and sufficient for interaction with IN. Since this region is also important for association with other members of mammalian SNF/SWI complex, we propose that this is a novel protein-protein interaction motif. The fact that HIV-1 IN binds to this highly conserved motif indicates that IN-Inil interaction is functionally significant. We have been able to isolate several cDNA clones that express the proteins that are able to specifically interact with Inil. Sequence analysis will reveal if any of these interacting proteins are part of SNF/SWI complex, part of holoenzyme complex, gene specific activators or any recombination proteins, understanding the function of which will shed light on the role of Inil in HIV-1 integration.

Keywords: AEGIS, HIV Integrase, DNA-Binding Proteins, Carrier Proteins, Transcription Factors, Chromatin, host factors, HIV-1, DNA, DNA, Complementary, integrase interactor 1, Human, ICA11

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ThA380