Protein-Protein Interactions of HIV-1 Integrase

Project: Research project

Project Details


The long-term goal of our project is to understand the complex and dynamic interplay between the host
and the virus, specifically focusing on HIV-1 integrase (IN) protein-protein interactions. Virally encoded IN
enzyme is required for insertion of viral DNA into host chromosomal DNA. Several host factors, including
INI1/hSNF5, directly bind to HIV-1 IN. INI1/hSNF5 plays multiple roles during HIV-1 replication. It is selectively
encapsidated into HIV-1 virions by its association with IN. Dominant negative mutants of INI1 selectively inhibit
HIV-1 particle production. INI1/hSNF5 in the producer cells and that encapsidated in the virions are required
for HIV-1 replication. One report using RNA interference analysis indicated that INI1/hSNF5 present in the
target cells is inhibitory to HIV-1 replication. INI1 is also required for Tat-mediated transactivation. Our
hypothesis is that multiple INI1-mediated effects are due to its varied functions resulting from its ability to
associate with many functionally distinct multi-protein complexes. INI1 is a component of the ATP-dependent
human chromatin remodeling SWI/SNF complex. Furthermore, our recent studies indicate that INI1 and IN
directly bind to SAP18 (Sin3a-associated protein 18kDa), a component of the Sin3a-HDAC(Histone
deacetylase)1 complex. Components of Sin3a-HDAC1 but NOT that of SWI/SNF complex are specifically
incorporated into HIV-1 virions and are required for early post-entry reverse transcription events in the target
cells. Based on these results we hypothesize that virion associated IN-INI1-SAP18-HDAC1 complex is
required for reverse transcription in the target cells during HIV-1 replication. The goal of this proposal is
to dissect the interplay between INI1-SAP18-IN interactions and determine the influence of HDAC1 complex
during HIV-1 replication, especially at reverse transcription. In Aim I, we will segregate proviral and antiviral
functions of INI1 by dissecting the role of multiple INI1-mediated associated complexes during HIV-1
replication. By targeting specificity subunits and using catalytic inactive subunits of SWI/SNF and HDAC1
complexes, we will determine how different complexes affect different functions of INI1 during HIV-1. In Aim II,
we will carry out genetic and functional analyses to probe INI1-SAP18 and IN-INI1 interactions by: (i) isolating
and functionally characterizing SAP18-interaction-defective mutants of INI1;(ii) functionally characterizing
panel of IN mutants defective for INI1 interaction and test the recruitment of HDAC1 complex, infectivity and
effect on reverse transcription. In Aim III, we will determine the mechanism by which virion-associated HDAC1
complex regulate RT function, by testing the hypothesis that deacetylation of IN or (another substrate) by
virion-associated HDAC1 is required for efficient reverse transcription in target cells;and determine the
relationship of IN mutants blocked for RT function and recruitment of HDAC1 complex. We hope that our
tudies will provide hitherto unanticipated role of HDAC1 complex in HIV-1 replication and shed light on
ntricate host-virus dynamic interactions, providing new avenues for anti-HIV-1 strategies.
Effective start/end date4/1/103/31/12


  • National Institute of Allergy and Infectious Diseases: $410,855.00


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