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Poly(ADP-Ribose) Polymerase Enhances Activator-Dependent Transcription in vitro
Michael Meisterernst, Gertraud Stelzer and Robert G. Roeder
Proceedings of the National Academy of Sciences of the United States of America
Vol. 94, No. 6 (Mar. 18, 1997), pp. 2261-2265
Published by: National Academy of Sciences
Stable URL: http://www.jstor.org/stable/41625
Page Count: 5
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Mammalian cells contain activities that amplify the effects of activators on class II gene transcription in vitro. The molecular identity of several of these cofactor activities is still unknown. Here we identify poly(ADP-ribose) polymerase (PARP) as one functional component of the positive cofactor 1 activity. PARP enhances transcription by acting during preinitiation complex formation, but at a step after binding of transcription factor IID. This transcriptional activation requires the amino-terminal DNA-binding domain, but not the carboxyl-terminal catalytic region. In purified systems, coactivator function requires a large molar excess of PARP over the number of templates, as reported for other DNA-binding cofactors such as topoisomerase I. PARP effects on supercoiled templates are DNA concentration-dependent and do not depend on damaged DNA. The PARP coactivator function is suppressed by NAD+, probably as a result of auto-ADP-ribosylation. These observations provide another example of the potentiation of transcription by certain DNA-binding cofactors and may point to interactions of PARP with RNA polymerase II-associated factors in special situations.
Proceedings of the National Academy of Sciences of the United States of America © 1997 National Academy of Sciences