scholarly journals DnaK Chaperone-Mediated Control of Activity of a ς32 Homolog (RpoH) Plays a Major Role in the Heat Shock Response of Agrobacterium tumefaciens

2001 ◽  
Vol 183 (18) ◽  
pp. 5302-5310 ◽  
Author(s):  
Kenji Nakahigashi ◽  
Hideki Yanagi ◽  
Takashi Yura
Keyword(s):  
Agrobacterium Tumefaciens ◽  
Heat Shock ◽  
Heat Shock Response ◽  
Induction Phase ◽  
Primary Role ◽  
E Coli ◽  
Essentially Normal ◽  
Shock Response ◽  
Shock Proteins ◽  
Adaptation Phase

ABSTRACT RpoH (Escherichia coli ς32 and its homologs) is the central regulator of the heat shock response in gram-negative proteobacteria. Here we studied salient regulatory features of RpoH in Agrobacterium tumefaciens by examining its synthesis, stability, and activity while increasing the temperature from 25 to 37°C. Heat induction of RpoH synthesis occurred at the level of transcription from an RpoH-dependent promoter, coordinately with that of DnaK, and followed by an increase in the RpoH level. Essentially normal induction of heat shock proteins was observed even with a strain that was unable to increase the RpoH level upon heat shock. Moreover, heat-induced accumulation of dnaK mRNA occurred without protein synthesis, showing that preexisting RpoH was sufficient for induction of the heat shock response. These results suggested that controlling the activity, rather than the amount, of RpoH plays a major role in regulation of the heat shock response. In addition, increasing or decreasing the DnaK-DnaJ chaperones specifically reduced or enhanced the RpoH activity, respectively. On the other hand, the RpoH protein was normally stable and remained stable during the induction phase but was destabilized transiently during the adaptation phase. We propose that the DnaK-mediated control of RpoH activity plays a primary role in the induction of heat shock response in A. tumefaciens, in contrast to what has been found in E. coli.

scholarly journals Differential and Independent Roles of a ς32 Homolog (RpoH) and an HrcA Repressor in the Heat Shock Response of Agrobacterium tumefaciens

1999 ◽  
Vol 181 (24) ◽  
pp. 7509-7515 ◽  
Author(s):  
Kenji Nakahigashi ◽  
Eliora Z. Ron ◽  
Hideki Yanagi ◽  
Takashi Yura
Keyword(s):  
Agrobacterium Tumefaciens ◽  
Heat Shock ◽  
Heat Shock Proteins ◽  
Heat Shock Response ◽  
Double Mutant ◽  
Negative Regulator ◽  
Gamma Proteobacteria ◽  
Essentially Normal ◽  
Shock Response ◽  
Shock Proteins

ABSTRACT The heat shock response in alpha proteobacteria is unique in that a combination of two regulators is involved: a positive regulator, RpoH (ς32 homolog), found in the alpha, beta, and gamma proteobacteria, and a negative regulator, HrcA, widely distributed in eubacteria but not in the gamma proteobacteria. To assess the differential roles of the two regulators in these bacteria, we cloned the hrcA-grpE operon of Agrobacterium tumefaciens, analyzed its transcription, and constructed deletion mutants lacking RpoH and/or HrcA. The ΔrpoH mutant andΔrpoH ΔhrcA double mutant were unable to grow above 30°C. Whereas the synthesis of heat shock proteins (e.g., DnaK, GroEL, and ClpB) was transiently induced upon temperature upshift from 25 to 37°C in the wild type, such induction was not observed in theΔrpoH mutant, except that GroEL synthesis was still partially induced. By contrast, the ΔhrcA mutant grew normally and exhibited essentially normal heat induction except for a higher level of GroEL expression, especially before heat shock. TheΔrpoH ΔhrcA double mutant showed the combined phenotypes of each of the single mutants. The amounts ofdnaK and groE transcripts before and after heat shock, as determined by primer extension, were consistent with those of the proteins synthesized. The cellular level of RpoH but not HrcA increased significantly upon heat shock. We conclude that RpoH plays a major and global role in the induction of most heat shock proteins, whereas HrcA plays a restricted role in repressing groEexpression under nonstress conditions.

scholarly journals Acyadeletion mutant ofEscherichia colidevelops thermotolerance but does not exhibit a heat-shock response

1990 ◽  
Vol 55 (1) ◽  
pp. 1-6 ◽  
Author(s):  
John M. Delaney
Keyword(s):  
Protein Synthesis ◽  
Heat Shock ◽  
Heat Shock Protein ◽  
Heat Shock Response ◽  
Receptor Protein ◽  
Wild Type ◽  
E Coli ◽  
Shock Response ◽  
In The Wild ◽  
Shock Proteins

SummaryAn adenyl cyclase deletion mutant (cya) ofE. colifailed to exhibit a heat-shock response even after 30 min at 42 °C. Under these conditions, heat-shock protein synthesis was induced by 10 min in the wild-type strain. These results suggest that synthesis of heat-shock proteins inE. colirequires thecyagene. This hypothesis is supported by the finding that a presumptive cyclic AMP receptor protein (CRP) binding site exists within the promotor region of theE. coli htp Rgene. In spite of the absence of heat-shock protein synthesis, when treated at 50 °C, thecyamutant is relatively more heat resistant than wild type. Furthermore, when heat shocked at 42 °C prior to exposure at 50 °C, thecyamutant developed thermotolerance. These results suggest that heat-shock protein synthesis is not essential for development of thermotolerance inE. coli.

scholarly journals Heat Shock Proteome of Agrobacterium tumefaciens: Evidence for New Control Systems

2002 ◽  
Vol 184 (6) ◽  
pp. 1772-1778 ◽  
Author(s):  
Ran Rosen ◽  
Knut Büttner ◽  
Dörte Becher ◽  
Kenji Nakahigashi ◽  
Takashi Yura ◽  
...  
Keyword(s):  
Agrobacterium Tumefaciens ◽  
Heat Shock ◽  
Heat Shock Proteins ◽  
Control Systems ◽  
Heat Shock Response ◽  
Proteome Analysis ◽  
Regulatory Factors ◽  
Shock Response ◽  
Shock Proteins ◽  
Heat Shock Induction

ABSTRACT The regulation of Agrobacterium tumefaciens heat shock genes involves a transcriptional activator (RpoH) and repressor elements (HrcA-CIRCE). Using proteome analysis and mutants in these control elements, we show that the heat shock induction of 32 (out of 56) heat shock proteins is independent of RpoH and HrcA. These results indicate the existence of additional regulatory factors in the A. tumefaciens heat shock response.

Urea sensitizes mIMCD3 cells to heat shock-induced apoptosis: protection by NaCl

2001 ◽  
Vol 280 (3) ◽  
pp. C614-C620 ◽  
Author(s):  
Chantal Colmont ◽  
Stéphanie Michelet ◽  
Dominique Guivarc'h ◽  
Germain Rousselet
Keyword(s):  
Heat Shock ◽  
Heat Shock Response ◽  
Heat Sensitivity ◽  
Osmotic Gradient ◽  
Water Reabsorption ◽  
Apoptotic Pathway ◽  
Shock Response ◽  
Induced Apoptosis ◽  
Shock Proteins ◽  
Dose Dependent

Urea, with NaCl, constitutes the osmotic gradient that allows water reabsorption in mammalian kidneys. Because NaCl induces heat shock proteins, we tested the responses to heat shock of mIMCD3 cells adapted to permissive urea and/or NaCl concentrations. We found that heat-induced cell death was stronger after adaptation to 250 mM urea. This effect was reversible, dose dependent, and, interestingly, blunted by 125 mM NaCl. Moreover, we have shown that urea-adapted cells engaged in an apoptotic pathway upon heat shock, as shown by DNA laddering. This sensitization is not linked to a defect in the heat shock response, because the induction of HSP70 was similar in isotonic and urea-adapted cells. Moreover, it is not linked to the presence of urea inside cells, because washing urea away did not restore heat resistance and because applying urea and heat shock at the same time did not lead to heat sensitivity. Together, these results suggest that urea modifies the heat shock response, leading to facilitated apoptosis.

scholarly journals Se Alleviated Oxidative Stress-Mediated Complex Poisoning Mechanism in Pb-Treated Chicken Kidneys: Inflammation, Heat Shock Response, and Autophagy

2021 ◽  
Author(s):  
Zhiying Miao ◽  
Weikang Yu ◽  
Yueyang Wang ◽  
Xianhong Gu ◽  
Xiaohua Teng
Keyword(s):  
Oxidative Stress ◽  
Heat Shock ◽  
Protein Expression ◽  
Heat Shock Response ◽  
Potable Water ◽  
Histological Structure ◽  
Standard Diet ◽  
Shock Response ◽  
Mrna And Protein Expression ◽  
Shock Proteins

Abstract Background: Lead (Pb) is a toxic environmental pollutant and can exerts toxicity in kidneys. It is known that selenium (Se) has an antagonistic effect on Pb poisoning. However, biological events during the process were not well understood in chicken kidneys.Methods: One hundred and eighty male Hyline chickens (7-day-old) were randomly divided into the control group (offering standard diet and potable water), the Se group (offering Na2SeO3-added standard diet and potable water), the Pb group (offering standard diet and (CH3OO)2Pb-added potable water), and the Pb+Se group (offering Na2SeO3-added standard diet and (CH3OO)2Pb-added potable water). On 30th, 60th, and 90th days, kidneys were removed to perform the studies of histological structure, oxidative stress indicators, cytokines, heat shock proteins, and autophagy in the chicken kidneys.Results: The experimental results indicated that Pb poisoning changed renal histological structure; decreased catalase, glutathione-s-transferase, and total antioxidative capacity activities; increased hydrogen peroxide content; induced mRNA and protein expression of heat shock proteins; inhibited interleukin (IL)-2 mRNA expression, and induced IL-4 and IL-12β mRNA expression; inhibited mammalian target of rapamycin mRNA and protein expression, and induced autophagy-related gene mRNA and protein expression in the chicken kidneys. Supplement of Se mitigated the above changes caused by Pb.Conclusion: Our research strengthens the evidence that Pb induced oxidative stress, inflammation, heat shock response, and autophagy and Se administration alleviated Pb poisoning through mitigating oxidative stress in the chicken kidneys.

scholarly journals Activation of the heat shock response in a primary cellular model of motoneuron neurodegeneration-evidence for neuroprotective and neurotoxic effects

2009 ◽  
Vol 14 (2) ◽  
Author(s):  
Bernadett Kalmar ◽  
Linda Greensmith
Keyword(s):  
Cell Death ◽  
Heat Shock ◽  
Heat Shock Response ◽  
Apoptotic Cell ◽  
Experimental Conditions ◽  
Pharmacological Agents ◽  
Shock Response ◽  
Induced Apoptosis ◽  
Shock Proteins ◽  
The Relationship

AbstractPharmacological up-regulation of heat shock proteins (hsps) rescues motoneurons from cell death in a mouse model of amyotrophic lateral sclerosis. However, the relationship between increased hsp expression and neuronal survival is not straightforward. Here we examined the effects of two pharmacological agents that induce the heat shock response via activation of HSF-1, on stressed primary motoneurons in culture. Although both arimoclomol and celastrol induced the expression of Hsp70, their effects on primary motoneurons in culture were significantly different. Whereas arimoclomol had survival-promoting effects, rescuing motoneurons from staurosporin and H2O2 induced apoptosis, celastrol not only failed to protect stressed motoneurons from apoptosis under same experimental conditions, but was neurotoxic and induced neuronal death. Immunostaining of celastrol-treated cultures for hsp70 and activated caspase-3 revealed that celastrol treatment activates both the heat shock response and the apoptotic cell death cascade. These results indicate that not all agents that activate the heat shock response will necessarily be neuroprotective.

The efficacy of long-lasting residual drinking water disinfectants based on hydrogen peroxide and silver

2000 ◽  
Vol 42 (1-2) ◽  
pp. 293-298 ◽  
Author(s):  
R. Pedahzur ◽  
D. Katzenelson ◽  
N. Barnea ◽  
O. Lev ◽  
H.I. Shuval ◽  
...  
Keyword(s):  
Hydrogen Peroxide ◽  
Heat Shock ◽  
Stress Responses ◽  
Heat Shock Response ◽  
Chemical Properties ◽  
Bactericidal Effect ◽  
Physiological Effects ◽  
Mechanisms Of Toxicity ◽  
E Coli ◽  
Shock Response

The aim of the present work was to evaluate the disinfectant capacity and the possible fields of application of a combined silver and hydrogen peroxide (HP) water disinfectant. The findings demonstrated the high bactericidal action of silver (on E. coli) and its relatively ineffective virucidal effect (on MS-2 phage). HP was found to have a small bactericidal effect and a mild virucidal one. When combined, silver and HP usually exhibited a synergistic action on the viability of E. coli and on the luminescence of recombinant luminescent E. coli. In some instances, the combined bactericidal effects were 1000-fold higher than the sum of the separate ones. No increased virucidal action was observed. The biocidal action of the combination generally increased with increasing temperature and pH, and decreased in secondary and tertiary effluents. The physiological effects and mechanisms of toxicity of HP, silver and their combinations, were assessed by monitoring the induction of stress promoters upon exposure to the active agents, and by assessing the sensitivity of E. coli mutated in major stress responses to HP, silver and their combinations. The results showed that HP induced a wide array of stress responses, that both silver and HP induced promoters regulated by the heat shock response, and that the dnaK promoter (regulated by the heat shock response) was synergistically induced. The mutant sensitivity tests showed that bacteria deficient in the ability to activate central cellular stress responses (SOS, heat shock, stationary phase, oxidative) were hypersensitive to both HP and silver. These results imply that cellular proteins, and possibly the DNA, are the cellular moieties chiefly affected. The above findings suggest that the potentiated effect of HP and silver is a metabolically dependant/related process that stems from a combination and/or accumulation of physiological effects exerted by the active ingredients. The physico-chemical properties of the combined disinfectant, and its disinfection capacity, points to its potential application as a long-term secondary residual disinfectant for water of relatively high quality.

scholarly journals Disruption of the three cytoskeletal networks in mammalian cells does not affect transcription, translation, or protein translocation changes induced by heat shock.

1985 ◽  
Vol 5 (7) ◽  
pp. 1571-1581 ◽  
Author(s):  
W J Welch ◽  
J R Feramisco
Keyword(s):  
Heat Shock ◽  
Heat Shock Response ◽  
Mammalian Cells ◽  
Stress Proteins ◽  
Protein Translocation ◽  
Shock Response ◽  
Cytochalasin E ◽  
Cytoskeletal Networks ◽  
Shock Proteins ◽  
Cytoskeletal Elements

Mammalian cells show a complex series of transcriptional and translational switching events in response to heat shock treatment which ultimately lead to the production and accumulation of a small number of proteins, the so-called heat shock (or stress) proteins. We investigated the heat shock response in both qualitative and quantitative ways in cells that were pretreated with drugs that specifically disrupt one or more of the three major cytoskeletal networks. (These drugs alone, cytochalasin E and colcemid, do not result in induction of the heat shock response.) Our results indicated that disruption of the actin microfilaments, the vimentin-containing intermediate filaments, or the microtubules in living cells does not hinder the ability of the cell to undergo an apparently normal heat shock response. Even when all three networks were simultaneously disrupted (resulting in a loose, baglike appearance of the cells), the cells still underwent a complete heat shock response as assayed by the appearance of the heat shock proteins. In addition, the major induced 72-kilodalton heat shock protein was efficiently translocated from the cytoplasm into its proper location in the nucleus and nucleolus irrespective of the condition of the three cytoskeletal elements.

The heat shock response of E. coli is regulated by changes in the concentration of σ32

Nature ◽  
1987 ◽  
Vol 329 (6137) ◽  
pp. 348-351 ◽  
Author(s):  
David B. Straus ◽  
William A. Walter ◽  
Carol A. Gross
Keyword(s):  
Heat Shock ◽  
Heat Shock Response ◽  
E Coli ◽  
Shock Response
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