Recruitment and dynamics of proteasome association with rhTRIM5α cytoplasmic complexes during HIV-1 infection.

A variety of proteins have been identified that restrict infection by different viruses. One such restriction factor is the rhesus macaque variant of TRIM5α (rhTRIM5α), which potently blocks infection by HIV-1. The block to infection mediated by rhTRIM5α occurs early after entry into the host cell, generally prior to reverse transcription. However, proteasome inhibitors reveal an intermediate step of restriction in which virus can complete reverse transcription, but still fails to infect the cell. While proteasome inhibitors have been a useful tool in understanding how restriction takes place, the role of the proteasome itself during restriction has not yet been examined. Here, we characterize the interaction of rhTRIM5α and incoming virions with the proteasome. We show that proteasomes localize to rhTRIM5α cytoplasmic bodies, and this localization is more evident when the activity of the proteasome is inhibited pharmacologically. We also show that restricted virus associates with complexes of proteasomes and rhTRIM5α, suggesting that rhTRIM5α utilizes the proteasome during restriction. Finally, live cell imaging experiments reveal that virus associates with proteasomes, and proteasome inhibition affects the duration of association. Taken together, these studies implicate the proteasome as playing a functional role during rhTRIM5α restriction of incoming virions.