Control of RNA Polymerase II Elongation Potential by a Novel Carboxyl-terminal Domain Kinase

doi:10.1074/jbc.271.43.27176

Control of RNA Polymerase II Elongation Potential by a Novel Carboxyl-terminal Domain Kinase*

From the Department of Biochemistry, University of Iowa, Iowa City, Iowa 52242

^‡ To whom correspondence should be addressed. Tel.: 319-335-7910; Fax: 319-335-9570; E-mail: david-price{at}uiowa.edu

Abstract

The entry of RNA polymerase II into a productive mode of elongation is controlled, in part, by the postinitiation activity of positive transcription elongation factor b (P-TEFb) (Marshall, N. F., and Price, D. H. (1995) J. Biol. Chem. 270, 12335-12338). We report here that removal of the carboxyl-terminal domain (CTD) of the large subunit of RNA polymerase II abolishes productive elongation. Correspondingly, we found that P-TEFb can phosphorylate the CTD of pure RNA polymerase II. Furthermore, P-TEFb can phosphorylate the CTD of RNA polymerase II when the polymerase is in an early elongation complex. Both the function and kinase activity of P-TEFb are blocked by the drugs 5,6-dichloro-1-β-D-ribofuranosylbenzimidazole (DRB) and H-8. P-TEFb is distinct from transcription factor IIH (TFIIH) because the two factors have no subunits in common, P-TEFb is more sensitive to DRB than is TFIIH, and most importantly, TFIIH cannot substitute functionally for P-TEFb. We propose that phosphorylation of the CTD by P-TEFb controls the transition from abortive into productive elongation mode.

Footnotes

↵* This work was supported by National Institutes of Health Grant GM35500. The costs of publication of this article were defrayed in part by the payment of page charges. The article must therefore be hereby marked “advertisement” in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.
↵¹ The abbreviations used are:

HIV

human immunodeficiency virus

P-TEF

positive transcription elongation factor

N-TEF

negative transcription elongation factor

TFIIH

transcription factor IIH

CTD

carboxyl-terminal domain

PAGE

polyacrylamide gel electrophoresis

K_cN

K_cN cell nuclear extract.
↵² D. Chafin, J. Peng, and D. Price, manuscript in preparation.
- Received June 5, 1996.
- Revision received July 19, 1996.