scholarly journals Dissection of the regulatory mechanism of a heat-shock responsive promoter in Haloarchaea: a new paradigm for general transcription factor directed archaeal gene regulation

2008 ◽  
Vol 36 (9) ◽  
pp. 3031-3042 ◽  
Author(s):  
Q. Lu ◽  
J. Han ◽  
L. Zhou ◽  
J. A. Coker ◽  
P. DasSarma ◽  
...  
2007 ◽  
Vol 104 (11) ◽  
pp. 4630-4635 ◽  
Author(s):  
M. T. Facciotti ◽  
D. J. Reiss ◽  
M. Pan ◽  
A. Kaur ◽  
M. Vuthoori ◽  
...  

1992 ◽  
Vol 117 (6) ◽  
pp. 1151-1159 ◽  
Author(s):  
R Baler ◽  
WJ Welch ◽  
R Voellmy

Heat shock genes encode proteins (hsp's) that play important structural roles under normal circumstances and are essential to the cells' ability to survive environmental insults. Evidence is presented herein that transcriptional regulation of hsp gene expression is linked with the regulation of overall protein synthesis as well as with the accumulation of proteins denatured by stressful events. The factor that connects the three processes appears to be one of the hsp's, presumably a member(s) of the hsp70 family. Biochemical experiments demonstrate that complexes containing hsp70 and heat shock transcription factor, the specific regulator of hsp gene activity, are formed in the cells.


1994 ◽  
Vol 14 (11) ◽  
pp. 7557-7568 ◽  
Author(s):  
J Zuo ◽  
R Baler ◽  
G Dahl ◽  
R Voellmy

Heat stress regulation of human heat shock genes is mediated by human heat shock transcription factor hHSF1, which contains three 4-3 hydrophobic repeats (LZ1 to LZ3). In unstressed human cells (37 degrees C), hHSF1 appears to be in an inactive, monomeric state that may be maintained through intramolecular interactions stabilized by transient interaction with hsp70. Heat stress (39 to 42 degrees C) disrupts these interactions, and hHSF1 homotrimerizes and acquires heat shock element DNA-binding ability. hHSF1 expressed in Xenopus oocytes also assumes a monomeric, non-DNA-binding state and is converted to a trimeric, DNA-binding form upon exposure of the oocytes to heat shock (35 to 37 degrees C in this organism). Because endogenous HSF DNA-binding activity is low and anti-hHSF1 antibody does not recognize Xenopus HSF, we employed this system for mapping regions in hHSF1 that are required for the maintenance of the monomeric state. The results of mutagenesis analyses strongly suggest that the inactive hHSF1 monomer is stabilized by hydrophobic interactions involving all three leucine zippers which may form a triple-stranded coiled coil. Trimerization may enable the DNA-binding function of hHSF1 by facilitating cooperative binding of monomeric DNA-binding domains to the heat shock element motif. This view is supported by observations that several different LexA DNA-binding domain-hHSF1 chimeras bind to a LexA-binding site in a heat-regulated fashion, that single amino acid replacements disrupting the integrity of hydrophobic repeats render these chimeras constitutively trimeric and DNA binding, and that LexA itself binds stably to DNA only as a dimer but not as a monomer in our assays.


2021 ◽  
Vol 49 (7) ◽  
pp. 3856-3875
Author(s):  
Marina Kulik ◽  
Melissa Bothe ◽  
Gözde Kibar ◽  
Alisa Fuchs ◽  
Stefanie Schöne ◽  
...  

Abstract The glucocorticoid (GR) and androgen (AR) receptors execute unique functions in vivo, yet have nearly identical DNA binding specificities. To identify mechanisms that facilitate functional diversification among these transcription factor paralogs, we studied them in an equivalent cellular context. Analysis of chromatin and sequence suggest that divergent binding, and corresponding gene regulation, are driven by different abilities of AR and GR to interact with relatively inaccessible chromatin. Divergent genomic binding patterns can also be the result of subtle differences in DNA binding preference between AR and GR. Furthermore, the sequence composition of large regions (>10 kb) surrounding selectively occupied binding sites differs significantly, indicating a role for the sequence environment in guiding AR and GR to distinct binding sites. The comparison of binding sites that are shared shows that the specificity paradox can also be resolved by differences in the events that occur downstream of receptor binding. Specifically, shared binding sites display receptor-specific enhancer activity, cofactor recruitment and changes in histone modifications. Genomic deletion of shared binding sites demonstrates their contribution to directing receptor-specific gene regulation. Together, these data suggest that differences in genomic occupancy as well as divergence in the events that occur downstream of receptor binding direct functional diversification among transcription factor paralogs.


Genetics ◽  
1999 ◽  
Vol 153 (4) ◽  
pp. 1573-1581 ◽  
Author(s):  
Susanna Chou ◽  
Sukalyan Chatterjee ◽  
Mark Lee ◽  
Kevin Struhl

Abstract The general transcription factor IIA (TFIIA) forms a complex with TFIID at the TATA promoter element, and it inhibits the function of several negative regulators of the TATA-binding protein (TBP) subunit of TFIID. Biochemical experiments suggest that TFIIA is important in the response to transcriptional activators because activation domains can interact with TFIIA, increase recruitment of TFIID and TFIIA to the promoter, and promote isomerization of the TFIID-TFIIA-TATA complex. Here, we describe a double-shut-off approach to deplete yeast cells of Toa1, the large subunit of TFIIA, to <1% of the wild-type level. Interestingly, such TFIIA-depleted cells are essentially unaffected for activation by heat shock factor, Ace1, and Gal4-VP16. However, depletion of TFIIA causes a general two- to threefold decrease of transcription from most yeast promoters and a specific cell-cycle arrest at the G2-M boundary. These results indicate that transcriptional activation in vivo can occur in the absence of TFIIA.


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