Special Article

The Topology of Transcription by Immobilized Polymerases

FRANCISCO J. IBORRA, ANA POMBO, JOHN MCMANUS, DEAN A. JACKSON, AND PETER R. COOK
CRC Nuclear Structure and Function Research Group, Sir William Dunn School of Pathology, University of Oxford South Parks Road, Oxford OX1 3RE, United Kingdom

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Abstract
Current models for RNA synthesis involve an RNA polymerase that tracks along a static template. However, research on chromatin loops suggests that the template slides past a polymerase immobilized in a large transcription factory. The evidence for immobilized polymerases is reviewed, and a model for transcription by such fixed enzymes is presented. According to the model, gene activation would involve reducing gene-factory distance and increasing the affinity of a promoter for a factory. Locus controlling regions and enhancers would attach to a factory and increase the chances that a promoter could bind to a polymerase; after transcriptional termination, the gene would detach from the factory. As some RNA processing occurs cotranscriptionally, processing sites are also likely to be associated with the factory.

EXPERIMENTAL CELL RESEARCH 229
167-173 (1996)
ARTICLE NO. 0355
Copyright © 1996 Academic Press, Inc.