Ubiquitin is part of the retrovirus budding machinery
- *Department of Microbiology and Immunology and †Department of Cellular and Molecular Physiology, The Pennsylvania State University College of Medicine, 500 University Drive, P.O. Box 850, Hershey, PA 17033
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Edited by John M. Coffin, Tufts University School of Medicine, Boston, MA, and approved September 1, 2000 (received for review June 30, 2000)
Abstract
Retroviruses contain relatively large amounts of ubiquitin, but the significance of this finding has been unknown. Here, we show that drugs that are known to reduce the level of free ubiquitin in the cell dramatically reduced the release of Rous sarcoma virus, an avian retrovirus. This effect was suppressed by overexpressing ubiquitin and also by directly fusing ubiquitin to the C terminus of Gag, the viral protein that directs budding and particle release. The block to budding was found to be at the plasma membrane, and electron microscopy revealed that the reduced level of ubiquitin results in a failure of mature virus particles to separate from each other and from the plasma membrane during budding. These data indicate that ubiquitin is actually part of the budding machinery.
Footnotes
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↵ ‡ To whom reprint requests should be addressed. E-mail: jwills{at}psu.edu.
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This paper was submitted directly (Track II) to the PNAS office.
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See commentary on page 12945.
- Abbreviations:
- Ub,
- ubiquitin;
- RSV,
- Rous sarcoma virus;
- L domain,
- late domain;
- GFP,
- green fluorescent protein;
- AP,
- adaptor protein
- Copyright © 2000, The National Academy of Sciences
