HIV-1 Rev oligomerization is not obligatory in the presence of an extra basic domain

BACKGROUND: The HIV-1 Rev regulatory protein binds as an oligomeric complex to viral RNA mediating nuclear export of incompletely spliced and non-spliced viral mRNAs encoding the viral structural proteins. However, the biological significance of the obligatory complex formation of Rev upon the viral RNA is unclear. RESULTS: The activity of various fusion proteins based on the negative oligomerization-defect Rev mutant M4 was tested using Rev dependent reporter constructs. An artificial M4 mutant dimer and an M4 mutant containing an extra basic domain from the HTLV-I Rex protein exhibited nearly full activity when compared to wild type Rev. CONCLUSION: Rev dimerization appears to be required to expose free basic domains whilst the Rev oligomeric complex remains bound to viral RNA via other basic domains.