2nd National Conference Human Retroviruses and Related Infections Washington, DC - January 29 - February 2, 1995

Natl Conf Hum Retrovir Relat Infect 1995 Jan 29-Feb 2;2: (abstract no. 30)

Mahalingam S¹, Khan SA², Jabbar MA³, Monken C¹, Collman R⁴, Srinivasan A^1
1Thomas Jefferson University, Philadelphia. ²Infinity Biotech, Philadelphia, PA; ³The Cleveland Clinic Foundation, Cleveland, OH; ⁴University of Pennsylvania, Philadelphia, PA

HIV-1 vpr encodes a 96 amino acid protein and shares homology with vpr and vpx of HIV-2/SIV. The structural features of HIV-1 Vpr include an acidic N-terminal domain containing a putative amphipathic alpha helix(17-34), a middle region with potential to form a beta sheet (36-87), a conserved cysteine residue(76) and a C-terminus rich in basic residues. To identify the domains of Vpr essential for incorporation into virus particles and its role in HIV-1 replication, site-specific mutagenesis of Vpr was carried out. Mutations that disrupt the potential helical structure of Vpr eliminated the virion incorporation function and alterations in the cysteine(76) and other conserved residues (65,87 and 95) did not impair the incorporation of Vpr into the virus-like particle directed by HIV-1 gag. We also constructed Chimeric Vpr involving HIV-1 Vpr and Vpx of HIV- 2 to identify the domains involved in virion incorporation. The conserved Cys residue was chosen as the site of fusion. Chimeric constructs containing N-terminal HIV-1 Vpr and C- terminal HIV-2 Vpr/Vpx exhibited incorporation function. The constructs containing 5' HIV-2 Vpr/Vpx and C-terminal HIV-1 Vpr did not show incorporation, indicating that N-terminus of HIV-1 Vpr confers specificity with respect to incorporation into virus-like particles. The role of Vpr in HIV-1 replication was also investigated using primary macrophages. Alteration at the Cys residue in Vpr, despite exhibiting virion incorporation function, showed a biological phenotype similar to Vpr-virus. These studies provide evidence for the presence of distinct functional domains in Vpr controlling different biological properties.

Keywords: Cell Nucleus, Genes, gag, Genes, vpr, HIV, HIV Long Terminal Repeat, HIV Protease, HIV-1, HIV-2, Mutagenesis, Site-Directed, Mutation, Virion, genetics

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1995-01-29
30

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