Role of ESCRT-I in retroviral budding.
Retroviral late-budding (L) domains are required for the efficient release of nascent virions. The three known types of L domain, designated according to essential tetrapeptide motifs (PTAP, PPXY, or YPDL), each bind distinct cellular cofactors. We and others have demonstrated that recruitment of an ESCRT-I subunit, Tsg101, a component of ... the class E vacuolar protein sorting (VPS) machinery, is required for the budding of viruses, such as human immunodeficiency virus type 1 (HIV-1) and Ebola virus, that encode a PTAP-type L domain, but subsequent events remain undefined. In this study, we demonstrate that VPS28, a second component of ESCRT-I, binds to a sequence close to the Tsg101 C terminus and is therefore recruited to the plasma membrane by HIV-1 Gag. In addition, we show that Tsg101 exhibits a multimerization activity. Using a complementation assay in which Tsg101 is artificially recruited to sites of HIV-1 assembly, we demonstrate that the integrity of the VPS28 binding site within Tsg101 is required for particle budding. In addition, mutation of a putative leucine zipper or residues important for Tsg101 multimerization also impairs the ability of Tsg101 to support HIV-1 budding. A minimal multimerizing Tsg101 domain is a dominant negative inhibitor of PTAP-mediated HIV-1 budding but does not inhibit YPDL-type or PPXY-type L-domain function. Nevertheless, YDPL-type L-domain activity is inhibited by expression of a catalytically inactive mutant of the class E VPS ATPase VPS4. These results indicate that all three classes of retroviral L domains require a functioning class E VPS pathway in order to effect budding. However, the PTAP-type L domain appears to be unique in its requirement for an intact, or nearly intact, ESCRT-I complex.
Mesh Terms:
Amino Acid Sequence, Animals, Binding Sites, Carrier Proteins, Cell Line, DNA-Binding Proteins, Dimerization, Endosomal Sorting Complexes Required for Transport, HIV-1, Humans, Leucine Zippers, Leukemia Virus, Murine, Mice, Molecular Sequence Data, Saccharomyces cerevisiae Proteins, Transcription Factors, Two-Hybrid System Techniques, Vesicular Transport Proteins, Virion
Amino Acid Sequence, Animals, Binding Sites, Carrier Proteins, Cell Line, DNA-Binding Proteins, Dimerization, Endosomal Sorting Complexes Required for Transport, HIV-1, Humans, Leucine Zippers, Leukemia Virus, Murine, Mice, Molecular Sequence Data, Saccharomyces cerevisiae Proteins, Transcription Factors, Two-Hybrid System Techniques, Vesicular Transport Proteins, Virion
J. Virol.
Date: Apr. 01, 2003
PubMed ID: 12663786
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