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Journal of Virology, December 2007, p. 13469-13477, Vol. 81, No. 24
0022-538X/07/$08.00+0 doi:10.1128/JVI.01097-07
Copyright © 2007, American Society for Microbiology. All Rights Reserved.
Proteins with Activated STAT1
Department of Microbiology, Mount Sinai School of Medicine, New York, New York 10029
Received 21 May 2007/ Accepted 24 September 2007
The Zaire ebolavirus protein VP24 was previously demonstrated to inhibit alpha/beta interferon (IFN-
/ß)- and IFN-
-induced nuclear accumulation of tyrosine-phosphorylated STAT1 (PY-STAT1) and to inhibit IFN-
/ß- and IFN-
-induced gene expression. These properties correlated with the ability of VP24 to interact with the nuclear localization signal receptor for PY-STAT1, karyopherin
1. Here, VP24 is demonstrated to interact not only with overexpressed but also with endogenous karyopherin
1. Mutational analysis demonstrated that VP24 binds within the PY-STAT1 binding region located in the C terminus of karyopherin
1. In addition, VP24 was found to inhibit PY-STAT1 binding to both overexpressed and endogenous karyopherin
1. We assessed the binding of both PY-STAT1 and the VP24 proteins from Zaire, mouse-adapted Zaire, and Reston Ebola viruses for interaction with all six members of the human karyopherin
family. We found, in contrast to previous studies, that PY-STAT1 can interact not only with karyopherin
1 but also with karyopherins
5 and
6, which together comprise the NPI-1 subfamily of karyopherin
s. Similarly, all three VP24s bound and inhibited PY-STAT1 interaction with karyopherins
1,
5, and
6. Consistent with their ability to inhibit the karyopherin-PY-STAT1 interaction, Zaire, mouse-adapted Zaire, and Reston Ebola virus VP24s displayed similar capacities to inhibit IFN-ß-induced gene expression in human and mouse cells. These findings suggest that VP24 inhibits interaction of PY-STAT1 with karyopherins
1,
5, or
6 by binding within the PY-STAT1 binding region of the karyopherins and that this function is conserved among the VP24 proteins of different Ebola virus species.
Published ahead of print on 10 October 2007.
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