EXCHANGE OF FUNCTIONAL DOMAINS BETWEEN REV PROTEINS OF HIV-1 AND SIVMAC239 RESULTS IN A DOMINANT-NEGATIVE PHENOTYPE

The Rev proteins of primate immunodeficiency viruses are essential tra nsactivators to switch from early to late phase in the viral replicati on cycle. Surprisingly, the Rev protein of HIV-1 is able to substitute those of HIV-2 and, as shown in here, of SIVmac239, but not vice vers a. To understand the underlying mechanism of this incomplete functiona l reciprocity, we constructed a series of chimeric HIV-1/SIVmac239 Rev proteins and tested them for transcomplementation efficacy on Rev-dep endent indicator plasmids. In addition, we analyzed the prokaryoticall y expressed wild type and chimeric proteins for RNA-binding properties in a gel-shift assay in vitro. The functional defect of SIVmac239 on the HIV-1 Rev response element (RRE) is not due to a lack of binding o r multimerization. In cotransfection experiments, SIVmac239 Rev and th e chimeric proteins were tested for potential inhibitory effects on HI V-1 Rev function using the HIV-1 based indicator plasmid. Some of thes e proteins turned out to be transdominant inhibitors almost as potent as the HIV-1 Rev mutant M10 which is localized in the activation domai n and is one of the strongest transdominant inhibitors. Surprisingly, M10 was not able to inhibit the function of either Rev protein on SIVm ac239 RRE, whereas a corresponding SIVmac239 Rev mutant (SIV M10) was a transdominant inhibitor of SIVmac239 Rev function on its homologous RRE. (C) 1994 Academic Press, Inc.