scholarly journals The Helicobacter pylori Heat-Shock Repressor HspR: Definition of Its Direct Regulon and Characterization of the Cooperative DNA-Binding Mechanism on Its Own Promoter

2018 ◽  
Vol 9 ◽  
Author(s):  
Simona Pepe ◽  
Eva Pinatel ◽  
Elisabetta Fiore ◽  
Simone Puccio ◽  
Clelia Peano ◽  
...  
Keyword(s):  
Helicobacter Pylori ◽  
Heat Shock ◽  
Dna Binding ◽  
Binding Mechanism ◽  
Definition Of

scholarly journals Cloning and characterization of two mouse heat shock factors with distinct inducible and constitutive DNA-binding ability.

1991 ◽  
Vol 5 (10) ◽  
pp. 1902-1911 ◽  
Author(s):  
K D Sarge ◽  
V Zimarino ◽  
K Holm ◽  
C Wu ◽  
R I Morimoto
Keyword(s):  
Heat Shock ◽  
Dna Binding ◽  
Heat Shock Factors ◽  
Binding Ability

scholarly journals Helicobacter pylori Stress-Response: Definition of the HrcA Regulon

2019 ◽  
Vol 7 (10) ◽  
pp. 436 ◽  
Author(s):  
Davide Roncarati ◽  
Eva Pinatel ◽  
Elisabetta Fiore ◽  
Clelia Peano ◽  
Stefany Loibman ◽  
...  
Keyword(s):  
Helicobacter Pylori ◽  
Heat Shock ◽  
Molecular Chaperones ◽  
Transcriptional Control ◽  
Protective Mechanism ◽  
Sudden Increase ◽  
Bacterial Survival ◽  
Whole Transcriptome Analysis ◽  
H Pylori ◽  
Definition Of

Bacteria respond to different environmental stresses by reprogramming the transcription of specific genes whose proper expression is critical for their survival. In this regard, the heat-shock response, a widespread protective mechanism, triggers a sudden increase in the cellular concentration of different proteins, including molecular chaperones and proteases, to preserve protein folding and maintain cellular homeostasis. In the medically important gastric pathogen Helicobacter pylori the regulation of the principal heat-shock genes is under the transcriptional control of two repressor proteins named HspR and HrcA. To define the HrcA regulon, we carried out whole transcriptome analysis through RNA-sequencing, comparing the transcriptome of the H. pylori G27 wild type strain to that of the isogenic hrcA-knockout strain. Overall, differential gene expression analysis outlined 49 genes to be deregulated upon hrcA gene inactivation. Interestingly, besides controlling the transcription of genes coding for molecular chaperones and stress-related mediators, HrcA is involved in regulating the expression of proteins whose function is linked to several cellular processes crucial for bacterial survival and virulence. These include cell motility, membrane transporters, Lipopolysaccharide modifiers and adhesins. The role of HrcA as a central regulator of H. pylori transcriptome, as well as its interconnections with the HspR regulon are here analyzed and discussed. As the HrcA protein acts as a pleiotropic regulator, influencing the expression of several stress-unrelated genes, it may be considered a promising target for the design of new antimicrobial strategies.

scholarly journals Characterization of a ComE3 Homologue Essential for DNA Transformation in Helicobacter pylori

2003 ◽  
Vol 71 (9) ◽  
pp. 5427-5431 ◽  
Author(s):  
Yu-Ching Yeh ◽  
Tzu-Lung Lin ◽  
Kai-Chih Chang ◽  
Jin-Town Wang
Keyword(s):  
Helicobacter Pylori ◽  
Dna Binding ◽  
Natural Transformation ◽  
Open Reading Frames ◽  
Dna Transformation ◽  
Knockout Mutant ◽  
Natural Competence ◽  
Mutant Complementation ◽  
Reading Frames

ABSTRACT To find genes involved in natural competence in Helicobacter pylori, we used a bioinformatics database search and found two transformation-related open reading frames (ORFs): a comE3 homologue (HP1361 ORF) of Bacillus subtilis and a comL homologue (HP1378 ORF) of Neisseria gonorrhoeae. We failed to obtain an HP1378 ORF knockout mutant, while an HP1361 ORF knockout mutant was obtained by transposon shuttle mutagenesis. The DNA transformation abilities of both natural transformation and electroporation were severely impaired (frequency, <10−9) in the HP1361− mutant. Complementation with a pHel2 vector carrying the HP1361 ORF restored the capabilities of natural competence (to a frequency of 4.21 × 10−7) and electroporation (to 3.62 × 10−7). The HP1361− mutant showed impairment in DNA binding and uptake. The results suggest that HP1361 is a comE3 homologue and is required for DNA binding and uptake during DNA transformation.

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.

Expression and characterization of an α-glucosidase from Thermoanaerobacter ethanolicus JW200 with potential for industrial application

Biologia ◽  
2009 ◽  
Vol 64 (6) ◽  
Author(s):  
Yue-Hong Wang ◽  
Yu Jiang ◽  
Zuo-Ying Duan ◽  
Wei-Lan Shao ◽  
Hua-Zhong Li
Keyword(s):  
Escherichia Coli ◽  
Heat Shock ◽  
Optimal Condition ◽  
Industrial Application ◽  
Conversion Rate ◽  
Hydrolytic Activity ◽  
Thermoanaerobacter Ethanolicus ◽  
Transglycosylation Activity

AbstractIn this study, a new α-glucosidase gene from Thermoanaerobacter ethanolicus JW200 was cloned and expressed in Escherichia coli by a novel heat-shock vector pHsh. The recombinant α-glucosidase exhibited its maximum hydrolytic activity at 70°C and pH 5.0∼5.5. With p-nitrophenyl-α-D-glucoside as a substrate and under the optimal condition (70°C, pH 5.5), K m and V max of the enzyme was 1.72 mM and 39 U/mg, respectively. The purified α-glucosidase could hydrolyze oligosaccharides with both α-1,4 and α-1,6 linkages. The enzyme also had strong transglycosylation activity when maltose was used as sugar donor. The transglucosylation products towards maltose are isomaltose, maltotriose, panose, isomaltotriose and tetrasaccharides. The enzyme could convert 400 g/L maltose to oligosaccharides with a conversion rate of 52%, and 83% of the oligosaccharides formed were prebiotic isomaltooligosaccharides (containing isomaltose, panose and isomaltotriose).

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