Tsg101 and the vacuolar protein sorting pathway are essential for HIV-1 budding

Like other enveloped viruses, HIV-1 uses cellular machinery to bud from inf ected cells. We now show that Tsg101 protein, which functions in vacuolar p rotein sorting (Vps), is required for HIV-1 budding. The UEV domain of Tsg1 01 binds to an essential tetrapeptide (PTAP) motif within the p6 domain of the structural Gag protein and also to ubiquitin. Depletion of cellular Tsg 101 by small interfering RNA arrests HIV-1 budding at a late stage, and bud ding is rescued by reintroduction of Tsg101. Dominant negative mutant Vps4 proteins that inhibit vacuolar protein sorting also arrest HIV-1 and MLV bu dding. These observations suggest that retroviruses bud by appropriating ce llular machinery normally used in the Vps pathway to form multivesicular bo dies.