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J Virol, August 1998, p. 6752-6757, Vol. 72, No. 8
Department of Molecular Genetics and
Biochemistry, University of Pittsburgh School of Medicine,
Pittsburgh, Pennsylvania 15261
Received 19 March 1998/Accepted 8 May 1998
ICP4 is an activator of herpes simplex virus early and late gene
transcription during infection and in vitro can efficiently activate
the transcription of a core promoter template containing only a TATA
box and an initiator element. In this study, we noted that the extent
of activation by ICP4 in vitro was highly dependent on the purity of
TFIID when recombinant TFIIB, TFIIE, and TFIIF were used as sources of
these factors. ICP4 efficiently activated transcription with a crude
TFIID fraction. However, when immunoaffinity-purified TFIID was used in
place of the less pure TFIID, ICP4 activated transcription to a
significantly lesser extent. This finding indicated that the crude
TFIID fraction may contain additional factors that serve as
coactivators of ICP4. To test this hypothesis, the crude TFIID
preparation was further fractionated by gel filtration chromatography. The TFIID that eluted from the column lacked the hypothesized coactivator activity. A fraction well separated from TFIID contained an
activity that when added with the TFIID fraction resulted in higher
levels of transcription in the presence ICP4. Further purification of
the coactivator-containing fraction resulted in the isolation of a
single 30-kDa polypeptide (p30). p30 was also shown to serve as a
coactivator of ICP4 with immunoaffinity-purified TFIID; however, p30
had no effect on basal transcription. Amino acid sequence analysis
revealed that p30 was the high mobility group protein 1, which has been
shown to facilitate the formation of higher-order DNA-protein
complexes.
0022-538X/98/$04.00+0
Copyright © 1998, American Society for Microbiology. All rights reserved.
The High Mobility Group Protein 1 Is a Coactivator
of Herpes Simplex Virus ICP4 In Vitro
*
Corresponding author. Mailing address: E1257 Biomedical
Science Tower, Department of Molecular Genetics and Biochemistry, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261. Phone: (412) 648-9947. Fax: (412) 624-1401. E-mail:
neal{at}hoffman.mgen.pitt.edu.
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