UMMS Affiliation

Howard Hughes Medical Institute; Program in Molecular Medicine; Program in Gene Function and Expression

Date

2-19-2005

Document Type

Article

Subjects

Animals; Gene Products, tat; Globins; HIV-1; Hela Cells; Humans; Promoter Regions (Genetics); Recombinant Proteins; TATA-Binding Protein Associated Factors; TATA-Box Binding Protein; *Transcription, Genetic; Transfection; tat Gene Products, Human Immunodeficiency Virus

Disciplines

Life Sciences | Medicine and Health Sciences

Abstract

The human immunodeficiency virus type I (HIV-1) transactivator protein Tat is an unusual transcriptional activator that is thought to act solely by promoting RNA polymerase II processivity. Here we study the mechanism of Tat action by analyzing transcription complex (TC) assembly in vivo using chromatin immunoprecipitation assays. We find, unexpectedly, that like typical activators Tat dramatically stimulates TC assembly. Surprisingly, however, the TC formed on the HIV-1 long terminal repeat is atypical and contains TATA-box-binding protein (TBP) but not TBP-associated factors (TAFs). Tat function involves direct interaction with the cellular cofactor positive transcription elongation factor b (P-TEFb). Artificial tethering of P-TEFb subunits to HIV-1 promoter DNA or nascent RNA indicates that P-TEFb is responsible for directing assembly of a TC containing TBP but not TAFs. On the basis of this finding, we identify P-TEFb-dependent cellular promoters that also recruit TBP in the absence of TAFs. Thus, in mammalian cells transcription of protein-coding genes involves alternative TCs that differ by the presence or absence of TAFs.

Rights and Permissions

Citation: PLoS Biol. 2005 Feb;3(2):e44. Epub 2005 Feb 8. Link to article on publisher's site

Related Resources

Link to Article in PubMed

PubMed ID

15719058

 
 

To view the content in your browser, please download Adobe Reader or, alternately,
you may Download the file to your hard drive.

NOTE: The latest versions of Adobe Reader do not support viewing PDF files within Firefox on Mac OS and if you are using a modern (Intel) Mac, there is no official plugin for viewing PDF files within the browser window.