Article
- The EMBO Journal (2004) 23, 2608 - 2619
- doi:10.1038/sj.emboj.7600275
Published online: 17 June 2004
Subject Categories:
Binding of the 7SK snRNA turns the HEXIM1 protein into a P-TEFb (CDK9/cyclin T) inhibitor
Annemieke A Michels1,a, Alessandro Fraldi2,a, Qintong Li3,a, Todd E Adamson3, François Bonnet1, Van Trung Nguyen1, Stanley C Sedore4, Jason P Price3, David H Price3, Luigi Lania2 and Olivier Bensaude1
- UMR 8541 CNRS, Ecole Normale Supérieure, Régulation de l'Expression Génétique, Paris, France
- Dipartimento di Genetica, Biologia Generale e Molecolare, Università di Napoli 'Federico II', Napoli, Italy
- Department of Biochemistry, University of Iowa, Iowa City, IA, USA
- Medical Scientist Training Program, University of Iowa, Iowa City, IA, USA
Correspondence to:
Olivier Bensaude, Laboratoire de Régulation de l'Expression Génétique, UMR 8541 CNRS, Ecole Normale Supérieure, 46, rue d Ulm, 75230 Paris Cedex 05, France. Tel.: +33 1 4432 3410; Fax: +33 1 4432 3941; E-mail: bensaude@wotan.ens.fr
aThese authors contributed equally to this work
Received 28 November 2003; Accepted 24 May 2004
Abstract
The positive transcription elongation factor b (P-TEFb) plays a pivotal role in productive elongation of nascent RNA molecules by RNA polymerase II. Core active P-TEFb is composed of CDK9 and cyclin T. In addition, mammalian cell extracts contain an inactive P-TEFb complex composed of four components, CDK9, cyclin T, the 7SK snRNA and the MAQ1/HEXIM1 protein. We now report an in vitro reconstitution of 7SK-dependent HEXIM1 association to purified P-TEFb and subsequent CDK9 inhibition. Yeast three-hybrid tests and gel-shift assays indicated that HEXIM1 binds 7SK snRNA directly and a 7SK snRNA-recognition motif was identified in the central part of HEXIM1 (amino acids (aa) 152–155). Data from yeast two-hybrid and pull-down assay on GST fusion proteins converge to a direct binding of P-TEFb to the HEXIM1 C-terminal domain (aa 181–359). Consistently, point mutations in an evolutionarily conserved motif (aa 202–205) were found to suppress P-TEFb binding and inhibition without affecting 7SK recognition. We propose that the RNA-binding domain of HEXIM1 mediates its association with 7SK and that P-TEFb then enters the complex through association with HEXIM1.
Keywords:
- HEXIM1,
- MAQ1,
- P-TEFb,
- RNA polymerase II,
- transcription
MORE ARTICLES LIKE THIS
These links to content published by NPG are automatically generated
REVIEWS
Pathogenesis of parkinson's disease: dopamine, vesicles and α-synuclein
Nature Reviews Neuroscience Review (01 Dec 2002)
NEWS AND VIEWS
Nuclear coupling: RNA processing reaches back to transcription
Nature Structural Biology News and Views (01 Nov 2002)
Nature Medicine News and Views (01 Feb 2003)
RESEARCH
A protein linkage map of Escherichia coli bacteriophage T7
Nature Genetics Article (01 Jan 1996)
The EMBO Journal Article (01 Jul 1998)
