Molecular and Cellular Biology, July 2001, p. 4427-4440, Vol. 21, No. 14
Department of Biochemistry and the Center for
Advanced Molecular Biology and Immunology, School of Medicine and
Biomedical Sciences, State University of New York at Buffalo, Buffalo,
New York 14214-3000
Received 28 March 2001/Accepted 30 April 2001
The general transcription factor IIB (TFIIB) is required for
transcription of class II genes by RNA polymerase II. Previous studies
demonstrated that mutations in the Saccharomyces cerevisiae SUA7 gene, which encodes TFIIB, can alter transcription
initiation patterns in vivo. To further delineate the functional domain
and residues of TFIIB involved in transcription start site utilization, a genetic selection was used to isolate S. cerevisiae TFIIB
mutants exhibiting downstream shifts in transcription initiation in
vivo. Both dominant and recessive mutations conferring downstream
shifts were identified at multiple positions within a highly conserved homology block in the N-terminal region of the protein. The TFIIB mutations conferred downstream shifts in transcription initiation at
the ADH1 and CYC1 promoters, whereas no
significant shifts were observed at the HIS3 promoter.
Analysis of a series of ADH1-HIS3 hybrid promoters and
variant ADH1 and HIS3 promoters containing insertions, deletions, or site-directed base substitutions revealed that the feature that renders a promoter sensitive to TFIIB mutations is the sequence in the immediate vicinity of the normal start sites. We
discuss these results in light of possible models for the mechanism of
start site utilization by S. cerevisiae RNA polymerase II
and the role played by TFIIB.
0270-7306/01/$04.00+0 DOI: 10.1128/MCB.21.14.4427-4440.2001
Copyright © 2001, American Society for Microbiology. All rights reserved.
Promoter-Specific Shifts in Transcription Initiation Conferred
by Yeast TFIIB Mutations Are Determined by the Sequence in the
Immediate Vicinity of the Start Sites
*
Corresponding author. Mailing address: Department of
Biochemistry, School of Medicine and Biomedical Sciences, SUNY Buffalo, 140 Farber Hall, 3435 Main St., Buffalo, NY 14214-3000. Phone: (716)
829-2473. Fax: (716) 829-2725. E-mail:
asp{at}acsu.buffalo.edu.
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