Heat shock transcription factor δ32 is targeted for degradation via an ubiquitin-like protein ThiS in Escherichia coli

2015 ◽  
Vol 459 (2) ◽  
pp. 240-245 ◽  
Author(s):  
Xibing Xu ◽  
Yulong Niu ◽  
Ke Liang ◽  
Jianmei Wang ◽  
Xufeng Li ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Transcription Factor ◽  
Heat Shock ◽  
Heat Shock Transcription Factor

scholarly journals Conserved Region 2.1 of Escherichia coli Heat Shock Transcription Factor σ32 Is Required for Modulating both Metabolic Stability and Transcriptional Activity

2004 ◽  
Vol 186 (22) ◽  
pp. 7474-7480 ◽  
Author(s):  
Mina Horikoshi ◽  
Takashi Yura ◽  
Sachie Tsuchimoto ◽  
Yoshihiro Fukumori ◽  
Masaaki Kanemori
Keyword(s):  
Escherichia Coli ◽  
Transcription Factor ◽  
Heat Shock ◽  
Transcriptional Activity ◽  
Heat Shock Transcription Factor ◽  
Metabolic Stability ◽  
Wild Type ◽  
Shock Proteins ◽  
Insight Into

ABSTRACT Escherichia coli heat shock transcription factor σ32 is rapidly degraded in vivo, with a half-life of about 1 min. A set of proteins that includes the DnaK chaperone team (DnaK, DnaJ, GrpE) and ATP-dependent proteases (FtsH, HslUV, etc.) are involved in degradation of σ32. To gain further insight into the regulation of σ32 stability, we isolated σ32 mutants that were markedly stabilized. Many of the mutants had amino acid substitutions in the N-terminal half (residues 47 to 55) of region 2.1, a region highly conserved among bacterial σ factors. The half-lives ranged from about 2-fold to more than 10-fold longer than that of the wild-type protein. Besides greater stability, the levels of heat shock proteins, such as DnaK and GroEL, increased in cells producing stable σ32. Detailed analysis showed that some stable σ32 mutants have higher transcriptional activity than the wild type. These results indicate that the N-terminal half of region 2.1 is required for modulating both metabolic stability and the activity of σ32. The evidence suggests that σ32 stabilization does not result from an elevated affinity for core RNA polymerase. Region 2.1 may, therefore, be involved in interactions with the proteolytic machinery, including molecular chaperones.

scholarly journals Activation of the DNA-binding ability of human heat shock transcription factor 1 may involve the transition from an intramolecular to an intermolecular triple-stranded coiled-coil structure.

1994 ◽  
Vol 14 (11) ◽  
pp. 7557-7568 ◽  
Author(s):  
J Zuo ◽  
R Baler ◽  
G Dahl ◽  
R Voellmy
Keyword(s):  
Transcription Factor ◽  
Heat Stress ◽  
Heat Shock ◽  
Dna Binding ◽  
Hydrophobic Interactions ◽  
Coiled Coil ◽  
Heat Shock Transcription Factor ◽  
Single Amino Acid ◽  
Binding Ability ◽  
Heat Shock Element

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.

Biochemical and Biophysical Characterization of the Trimerization Domain from the Heat Shock Transcription Factor†

Biochemistry ◽  
1999 ◽  
Vol 38 (12) ◽  
pp. 3559-3569 ◽  
Author(s):  
Ralph Peteranderl ◽  
Mark Rabenstein ◽  
Yeon-Kyun Shin ◽  
Corey W. Liu ◽  
David E. Wemmer ◽  
...  
Keyword(s):  
Transcription Factor ◽  
Heat Shock ◽  
Heat Shock Transcription Factor ◽  
Biophysical Characterization
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