Article
- The EMBO Journal (1997) 16, 163 - 172
- doi:10.1093/emboj/16.1.163
Identification of a transcript release activity acting on ternary transcription complexes containing murine RNA polymerase I
Stephen W. Mason2, Eva E. Sander3 and Ingrid Grummt1
- Division of Molecular Biology of the Cell II, German Cancer Research Center, 69120 Heidelberg, Germany
- Present address: Amgen Institute, 620 University Avenue, Toronto, M5G 2C1, Canada
- Present address: Netherlands Cancer Institute, Division of Cell Biology, 1066CX Amsterdam, The Netherlands
Correspondence to:
Ingrid Grummt,
Received 5 August 1996; Revised 20 September 1996
Abstract
Termination of mammalian ribosomal gene transcription by RNA polymerase I (Pol I) requires binding of the nucleolar factor TTF-I (transcription termination factor for Pol I) to specific rDNA terminator elements. We have used recombinant murine TTF-I in an immobilized tailed template assay to analyze individual steps of the termination reaction. We demonstrate that, besides the TTF-I–DNA complex which stops elongating Pol I, an additional activity is required to release both the nascent transcript and Pol I from the template. Moreover, transcript release, but not TTF-I-directed pausing, depends on upstream sequences directly flanking the terminator element. Together, complete termination of Pol I transcription requires TTF-I bound to the terminator DNA, a stretch of thymidine residues upstream of the TTF-I-mediated pause site and an activity which releases the RNA transcript and Pol I from the DNA template.
Keywords:
- RNA polymerase I,
- transcript release,
- transcription termination,
- TTF-I
