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J. Virol., 05 1995, 3125-3133, Vol 69, No. 5
J Katahira, T Ishizaki, H Sakai, A Adachi, K Yamamoto and H Shida
The viral transactivator proteins Rex and Rev are necessary for the
expression of structural proteins of human T-cell leukemia virus type I and
human immunodeficiency virus type 1, respectively. Although the interaction
of Rex/Rev with a cellular cofactor(s) has been thought to be required for
Rex/Rev action, there is no suitable system to search for the cofactor(s)
in mammalian cells. We found that a Rex mutant, TAgRex, which contains a
simian virus 40 nuclear localization signal in place of the N-terminal 19
amino acids of Rex, could dominantly inhibit wild-type Rex/Rev functions.
The inhibition did not require either Rev response element/Rex response
element binding or the oligomerization ability of the mutant, but it did
require a region around amino acid 90 of the Rex protein, suggesting that
TAgRex sequestered the cellular cofactor. Complementation with the
eukaryotic translation initiation factor 5A (eIF-5A) in this system could
restore the impaired Rex function. These results indicate that eIF-5A is
the cofactor indispensable for Rex function. Additionally, by using a
two-hybrid system, the homo-oligomer formation of Rex was found to be
mediated by the region around amino acid 90 in addition to Tyr-64 and
Trp-65 of Rex protein. Thus, eIF-5A may play a part in the formation of the
Rex homo- oligomer.
Copyright © 1995, American Society for Microbiology
Effects of translation initiation factor eIF-5A on the functioning of human T-cell leukemia virus type I Rex and human immunodeficiency virus Rev inhibited trans dominantly by a Rex mutant deficient in RNA binding
Institute for Virus Research, Kyoto University, Japan.
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