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Open Access Research

Human immunodeficiency virus type 1 Vpr: oligomerization is an essential feature for its incorporation into virus particles

Narasimhan J Venkatachari1, Leah A Walker1, Oznur Tastan2, Thien Le1, Timothy M Dempsey1, Yaming Li1, Naveena Yanamala3, Alagarsamy Srinivasan4, Judith Klein-Seetharaman23, Ronald C Montelaro5 and Velpandi Ayyavoo1*

Author Affiliations

1 Department of Infectious Diseases and Microbiology, Graduate School of Public Health, University of Pittsburgh, Pittsburgh, PA, USA

2 School of Computer Science, Carnegie Mellon University, Pittsburgh, PA, USA

3 Department of Structural Biology, University of Pittsburgh, Pittsburgh, PA, USA

4 NanoBio Diagnostics, West Chester, PA, USA

5 Vaccine Research Center, University of Pittsburgh, Pittsburgh, PA, USA

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Virology Journal 2010, 7:119  doi:10.1186/1743-422X-7-119

Published: 7 June 2010

Abstract

HIV-1 Vpr, a nonstructural viral protein associated with virus particles, has a positive role in the efficient transport of PIC into the nucleus of non-dividing target cells and enhances virus replication in primary T cells. Vpr is a 96 amino acid protein and the structure by NMR shows three helical domains. Vpr has been shown to exist as dimers and higher order oligomers. Considering the multifunctional nature of Vpr, the contribution of distinct helical domains to the dimer/oligomer structure of Vpr and the relevance of this feature to its functions are not clear. To address this, we have utilized molecular modeling approaches to identify putative models of oligomerization. The predicted interface residues were subjected to site-directed mutagenesis and evaluated their role in intermolecular interaction and virion incorporation. The interaction between Vpr molecules was monitored by Bimolecular Fluorescence complementation (BiFC) method. The results show that Vpr forms oligomers in live cells and residues in helical domains play critical roles in oligomerization. Interestingly, Vpr molecules defective in oligomerization also fail to incorporate into the virus particles. Based on the data, we suggest that oligomerization of Vpr is essential for virion incorporation property and may also have a role in the events associated with virus infection.