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Journal of Virology, May 1999, p. 3930-3940, Vol. 73, No. 5
Department of Microbiology and Kaplan
Comprehensive Cancer Center, New York University Medical Center,
New York, New York 10016
Received 23 October 1998/Accepted 21 January 1999
Herpes simplex virus infection is initiated by VP16, a viral
transcription factor that activates the viral immediate-early (IE)
genes. VP16 does not recognize the IE gene promoters directly but
instead forms a multiprotein complex with Oct-1 and HCF-1, a ubiquitous
nuclear protein required for progression through the G1
phase of the cell cycle. The functional significance of recruiting
HCF-1 to the VP16-induced complex is not understood. Here we describe
the identification of a second HCF-like protein, designated HCF-2.
HCF-2 is smaller than HCF-1 but shares three regions of strong amino
acid sequence homology, including the
0022-538X/99/$04.00+0
Copyright © 1999, American Society for Microbiology. All rights reserved.
Herpes Simplex Virus Transactivator VP16
Discriminates between HCF-1 and a Novel Family Member, HCF-2

-propeller domain required for
association with VP16. HCF-2 is expressed in many tissues, especially
the testis, and shows a more dynamic pattern of subcellular
localization than HCF-1. Although HCF-2 associates with VP16 and can
support complex assembly with Oct-1 and DNA, it is significantly less
efficient than HCF-1. A similar preference is shown by LZIP, a cellular
counterpart of VP16. Analysis of chimeric proteins showed that
differences between the fifth and sixth kelch repeats of the
-propeller domains from HCF-1 and HCF-2 dictate this selectivity.
These results reveal an unexpected level of specificity in the
recruitment of HCF-1 to the VP16-induced complex, paralleling the
preferential selection of Oct-1 rather than the closely related POU
domain protein Oct-2. Implications for regulation of the viral life
cycle are discussed.
*
Corresponding author. Mailing address: Department of
Microbiology, 550 First Ave., New York, NY 10016. Phone: (212)
263-0206. Fax: (212) 263-8276. E-mail:
wilsoa02{at}popmail.med.nyu.edu.
Present address: UCLA ACCESS, Molecular Biology Institute, Los
Angeles, CA 90024.
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