Manipulation of P-TEFb control machinery by HIV: recruitment of P-TEFb from the large form by Tat and binding of HEXIM1 to TAR

Stanley C Sedore; Sarah A Byers; Sebastian Biglione; Jason P Price; Wendy J Maury; David H Price

doi:10.1093/nar/gkm443

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Manipulation of P-TEFb control machinery by HIV: recruitment of P-TEFb from the large form by Tat and binding of HEXIM1 to TAR

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Manipulation of P-TEFb control machinery by HIV: recruitment of P-TEFb from the large form by Tat and binding of HEXIM1 to TAR

Stanley C Sedore, Sarah A Byers, Sebastian Biglione, Jason P Price, Wendy J Maury and David H Price

Nucleic acids research, Vol.35(13), pp.4347-4358

07/2007

DOI: 10.1093/nar/gkm443

PMCID: PMC1935001

PMID: 17576689

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Abstract

Basal transcription of the HIV LTR is highly repressed and requires Tat to recruit the positive transcription elongation factor, P-TEFb, which functions to promote the transition of RNA polymerase II from abortive to productive elongation. P-TEFb is found in two forms in cells, a free, active form and a large, inactive complex that also contains 7SK RNA and HEXIM1 or HEXIM2. Here we show that HIV infection of cells led to the release of P-TEFb from the large form. Consistent with Tat being the cause of this effect, transfection of a FLAG-tagged Tat in 293T cells caused a dramatic shift of P-TEFb out of the large form to a smaller form containing Tat. In vitro , Tat competed with HEXIM1 for binding to 7SK, blocked the formation of the P-TEFb–HEXIM1–7SK complex, and caused the release P-TEFb from a pre-formed P-TEFb–HEXIM1–7SK complex. These findings indicate that Tat can acquire P-TEFb from the large form. In addition, we found that HEXIM1 binds tightly to the HIV 5′ UTR containing TAR and recruits and inhibits P-TEFb activity. This suggests that in the absence of Tat, HEXIM1 may bind to TAR and repress transcription elongation of the HIV LTR.

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Title: Subtitle: Manipulation of P-TEFb control machinery by HIV: recruitment of P-TEFb from the large form by Tat and binding of HEXIM1 to TAR
Creators: Stanley C Sedore - Department of Biochemistry
Sarah A Byers - Department of Biochemistry
Sebastian Biglione - Department of Biochemistry
Jason P Price - Department of Biochemistry
Wendy J Maury - Department of Biochemistry
David H Price - Department of Biochemistry
Resource Type: Journal article
Publication Details: Nucleic acids research, Vol.35(13), pp.4347-4358
Publisher: Oxford University Press
DOI: 10.1093/nar/gkm443
PMID: 17576689
PMCID: PMC1935001
ISSN: 0305-1048
eISSN: 1362-4962
Language: English
Date published: 07/2007
Academic Unit: Microbiology and Immunology; Biochemistry and Molecular Biology
Record Identifier: 9984024420502771

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