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Journal of Virology, July 1999, p. 5388-5401, Vol. 73, No. 7
Departments of
Microbiology1 and
Medicine,2 College of Physicians and
Surgeons, Columbia University, New York, New York 10032
Received 25 January 1999/Accepted 26 March 1999
Human immunodeficiency virus type 1 (HIV-1) gag-encoded
proteins play key functions at almost all stages of the viral life cycle. Since these functions may require association with cellular factors, the HIV-1 matrix protein (MA) was used as bait in a yeast two-hybrid screen to identify MA-interacting proteins. MA was found to
interact with elongation factor 1-alpha (EF1
0022-538X/99/$04.00+0
Copyright © 1999, American Society for Microbiology. All rights reserved.
Translation Elongation Factor 1-Alpha Interacts
Specifically with the Human Immunodeficiency Virus Type 1 Gag
Polyprotein
), an essential component of the translation machinery that delivers aminoacyl-tRNA to
ribosomes. EF1
was then shown to bind the entire HIV-1 Gag polyprotein. This interaction is mediated not only by MA, but also by
the nucleocapsid domain, which provides a second, independent EF1
-binding site on the Gag polyprotein. EF1
is incorporated within HIV-1 virion membranes, where it is cleaved by the viral protease and protected from digestion by exogenously added subtilisin. The specificity of the interaction is demonstrated by the fact that
EF1
does not bind to nonlentiviral MAs and does not associate with
Moloney murine leukemia virus virions. The Gag-EF1
interaction appears to be mediated by RNA, in that basic residues in MA and NC are
required for binding to EF1
, RNase disrupts the interaction, and a
Gag mutant with undetectable EF1
-binding activity is impaired in its
ability to associate with tRNA in cells. Finally, the interaction between MA and EF1
impairs translation in vitro, a result consistent with a previously proposed model in which inhibition of translation by
the accumulation of Gag serves to release viral RNA from polysomes, permitting the RNA to be packaged into nascent virions.
*
Corresponding author. Mailing address: Departments of
Microbiology and Medicine, College of Physicians and Surgeons, Columbia University, 701 West 168th St., New York, NY 10032. Phone: (212) 305-8706. Fax: (212) 305-0333. E-mail:
Luban{at}cuccfa.ccc.columbia.edu.
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