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Molecular and Cellular Biology, November 1998, p. 6340-6352, Vol. 18, No. 11
Department of Biological Chemistry, The
University of Michigan Medical School, Ann Arbor, Michigan
48109-0606
Received 16 June 1998/Accepted 27 July 1998
The baker's yeast Saccharomyces cerevisiae possesses a
single gene encoding heat shock transcription factor (HSF), which is required for the activation of genes that participate in stress protection as well as normal growth and viability. Yeast HSF (yHSF) contains two distinct transcriptional activation regions located at the
amino and carboxyl termini. Activation of the yeast metallothionein gene, CUP1, depends on a nonconsensus heat shock element
(HSE), occurs at higher temperatures than other heat shock-responsive genes, and is highly dependent on the carboxyl-terminal transactivation domain (CTA) of yHSF. The results described here show that the noncanonical (or gapped) spacing of GAA units in the CUP1
HSE (HSE1) functions to limit the magnitude of CUP1
transcriptional activation in response to heat and oxidative stress.
The spacing in HSE1 modulates the dependence for transcriptional
activation by both stresses on the yHSF CTA. Furthermore, a previously
uncharacterized HSE in the CUP1 promoter, HSE2, modulates
the magnitude of the transcriptional activation of CUP1,
via HSE1, in response to stress. In vitro DNase I footprinting
experiments suggest that the occupation of HSE2 by yHSF strongly
influences the manner in which yHSF occupies HSE1. Limited
proteolysis assays show that HSF adopts a distinct protease-sensitive conformation when bound to the CUP1
HSE1, providing evidence that the HSE influences DNA-bound HSF
conformation. Together, these results suggest that CUP1
regulation is distinct from that of other classic heat shock genes
through the interaction of yHSF with two nonconsensus HSEs. Consistent
with this view, we have identified other gene targets of yHSF
containing HSEs with sequence and spacing features similar to those of
CUP1 HSE1 and show a correlation between the spacing of the
GAA units and the relative dependence on the yHSF CTA.
0270-7306/98/$04.00+0
Copyright © 1998, American Society for Microbiology. All rights reserved.
Heat Shock Element Architecture Is an Important Determinant in
the Temperature and Transactivation Domain Requirements for Heat
Shock Transcription Factor
and
*
Corresponding author. Mailing address: Department of
Biological Chemistry, The University of Michigan Medical School, Ann Arbor, MI 48109-0606. Phone: (734) 763-5717. Fax: (734) 763-4581. E-mail: dthiele{at}umich.edu.
Present address: MediCity Research Laboratory, University of Turku,
20520 Turku, Finland.
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