MCB
Home Help [Feedback] [For Subscribers] [Archive] [Search] [Contents]
This Article
Right arrow Full Text
Right arrow Full Text (PDF)
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrowReprints and Permissions
Right arrow Copyright Information
Right arrow Books from ASM Press
Right arrow MicrobeWorld
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Garber, M. E.
Right arrow Articles by Jones, K. A.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Garber, M. E.
Right arrow Articles by Jones, K. A.

 Previous Article  |  Next Article 

Molecular and Cellular Biology, September 2000, p. 6958-6969, Vol. 20, No. 18
0270-7306/00/$04.00+0
Copyright © 2000, American Society for Microbiology. All rights reserved.

CDK9 Autophosphorylation Regulates High-Affinity Binding of the Human Immunodeficiency Virus Type 1 Tat-P-TEFb Complex to TAR RNA

Mitchell E. Garber,1 Timothy P. Mayall,1 Eric M. Suess,1 Jill Meisenhelder,2 Nancy E. Thompson,3 and Katherine A. Jones1,*

Regulatory Biology Laboratory1 and Molecular Biology and Virology Laboratory,2 The Salk Institute for Biological Studies, La Jolla, California 92037, and McArdle Laboratory for Cancer Research, University of Wisconsin, Madison, Wisconsin 537063

Received 7 February 2000/Returned for modification 31 March 2000/Accepted 19 June 2000

Human immunodeficiency virus type 1 (HIV-1) Tat interacts with cyclin T1 (CycT1), a regulatory partner of CDK9 in the positive transcription elongation factor (P-TEFb) complex, and binds cooperatively with CycT1 to TAR RNA to recruit P-TEFb and promote transcription elongation. We show here that Tat also stimulates phosphorylation of affinity-purified core RNA polymerase II and glutathione S-transferase-C-terminal-domain substrates by CycT1-CDK9, but not CycH-CDK7, in vitro. Interestingly, incubation of recombinant Tat-P-TEFb complexes with ATP enhanced binding to TAR RNA dramatically, and the C-terminal half of CycT1 masked binding of Tat to TAR RNA in the absence of ATP. ATP incubation lead to autophosphorylation of CDK9 at multiple C-terminal Ser and Thr residues, and full-length CycT1 (amino acids 728) [CycT1(1-728)], but not truncated CycT1(1-303), was also phosphorylated by CDK9. P-TEFb complexes containing a catalytically inactive CDK9 mutant (D167N) bound TAR RNA weakly and independently of ATP, as did a C-terminal truncated CDK9 mutant that was catalytically active but unable to undergo autophosphorylation. Analysis of different Tat proteins revealed that the 101-amino-acid SF2 HIV-1 Tat was unable to bind TAR with CycT1(1-303) in the absence of phosphorylated CDK9, whereas unphosphorylated CDK9 strongly blocked binding of HIV-2 Tat to TAR RNA in a manner that was reversed upon autophosphorylation. Replacement of CDK9 phosphorylation sites with negatively charged residues restored binding of CycT1(1-303)-D167N-Tat, and rendered D167N a more potent inhibitor of transcription in vitro. Taken together, these results demonstrate that CDK9 phosphorylation is required for high-affinity binding of Tat-P-TEFb to TAR RNA and that the state of P-TEFb phosphorylation may regulate Tat transactivation in vivo.

* Corresponding author. Mailing address: Regulatory Biology Laboratory, The Salk Institute for Biological Studies, 10010 N. Torrey Pines Rd., La Jolla, CA 92037. Phone: (858) 452-1122. Fax: (858) 535-8194. E-mail: jones{at}salk.edu.

Molecular and Cellular Biology, September 2000, p. 6958-6969, Vol. 20, No. 18
0270-7306/00/$04.00+0
Copyright © 2000, American Society for Microbiology. All rights reserved.


This article has been cited by other articles:



Home Help [Feedback] [For Subscribers] [Archive] [Search] [Contents]
J. Bacteriol. J. Virol. Eukaryot. Cell
Microbiol. Mol. Biol. Rev. Clin. Vaccine Immunol. All ASM Journals

Copyright © 2000 by the American Society for Microbiology. All rights reserved.