Expression and purification of soluble HIV-2 viral protein R (Vpr) using a sandwich-fusion protein strategy

Viral accessory proteins of the human immunodeficiency virus (HIV), including virus protein R (Vpr), are crucial for the efficient replication of the virus in the host organism. While functional data are available for HIV-1 Vpr, there is a paucity of data describing the function and structure of HIV-2 Vpr. In this report, the construction of a His6-MBP-intein1-Vpr-intein2-Cyt b5-His6 fusion protein is presented. Unlike previous research efforts where only microgram quantities of HIV-1 Vpr could be produced, this construct enabled soluble milligram yields via an Escherichia coli over-expression system. Straightforward protein purification of HIV-2 Vpr was achieved by standard chromatography routines and autocatalytic intein cleavage. Preliminary structural studies by circular dichroism (CD) and NMR spectroscopy revealed that the protein is stable in the presence of micellar concentrations of the detergent DPC and adopts an α-helix secondary structure.