scholarly journals Feedback regulation of the heat shock response in E. coli

2003 ◽  
Author(s):  
H. Kurata ◽  
H. El-Samad ◽  
T.-M. Yi ◽  
M. Khammash ◽  
J. Doyle
Keyword(s):  
Heat Shock ◽  
Heat Shock Response ◽  
Feedback Regulation ◽  
E Coli ◽  
Shock Response

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.

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

scholarly journals Regulatory Conservation and Divergence of ς32 Homologs from Gram-Negative Bacteria: Serratia marcescens, Proteus mirabilis, Pseudomonas aeruginosa, and Agrobacterium tumefaciens

1998 ◽  
Vol 180 (9) ◽  
pp. 2402-2408 ◽  
Author(s):  
Kenji Nakahigashi ◽  
Hideki Yanagi ◽  
Takashi Yura
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Heat Shock ◽  
Serratia Marcescens ◽  
Proteus Mirabilis ◽  
Heat Shock Response ◽  
Gram Negative Bacteria ◽  
Heat Shock Genes ◽  
Gram Negative ◽  
E Coli ◽  
Shock Response

ABSTRACT The heat shock response in Escherichia coli is mediated primarily by the rpoH gene, encoding ς32, which is specifically required for transcription of heat shock genes. A number of ς32 homologs have recently been cloned from gram-negative bacteria that belong to the gamma or alpha subdivisions of the proteobacteria. We report here some of the regulatory features of several such homologs (RpoH) expressed in E. coli as well as in respective cognate bacteria. When expressed in an E. coli ΔrpoH strain lacking its own ς32, these homologs activated the transcription of heat shock genes (groE and dnaK) from the start sites normally used in E. coli. The level of RpoH inSerratia marcescens and Pseudomonas aeruginosacells was very low at 30°C but was elevated markedly upon a shift to 42°C, as found previously with E. coli. The increased RpoH levels upon heat shock resulted from both increased synthesis and stabilization of the normally unstable RpoH protein. In contrast, the RpoH level in Proteus mirabilis was relatively high at 30°C and increased less markedly upon heat shock, mostly by increased synthesis; this ς32 homolog was already stable at 30°C, and little further stabilization occurred upon the shift to 42°C. The increased synthesis of RpoH homologs in all these gamma proteobacteria was observed even in the presence of rifampin, suggesting that the induction occurred at the level of translation. Thus, the basic regulatory strategy of the heat shock response by enhancing the RpoH level is well conserved in the gamma proteobacteria, but some divergence in the actual mechanisms used occurred during evolution.

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 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 Convergence of Molecular, Modeling, and Systems Approaches for an Understanding of the Escherichia coli Heat Shock Response

2008 ◽  
Vol 72 (3) ◽  
pp. 545-554 ◽  
Author(s):  
Eric Guisbert ◽  
Takashi Yura ◽  
Virgil A. Rhodius ◽  
Carol A. Gross
Keyword(s):  
Escherichia Coli ◽  
Heat Shock ◽  
Heat Shock Response ◽  
Feedback Loop ◽  
Model Organism ◽  
Central Component ◽  
E Coli ◽  
Functional Aspects ◽  
Shock Response ◽  
Homeostatic Response

SUMMARY The heat shock response (HSR) is a homeostatic response that maintains the proper protein-folding environment in the cell. This response is universal, and many of its components are well conserved from bacteria to humans. In this review, we focus on the regulation of one of the most well-characterized HSRs, that of Escherichia coli. We show that even for this simple model organism, we still do not fully understand the central component of heat shock regulation, a chaperone-mediated negative feedback loop. In addition, we review other components that contribute to the regulation of the HSR in E. coli and discuss how these additional components contribute to regulation. Finally, we discuss recent genomic experiments that reveal additional functional aspects of the HSR.

scholarly journals Metabolic Roles of a Rhodobacter sphaeroides Member of the ς32 Family

1998 ◽  
Vol 180 (1) ◽  
pp. 10-19 ◽  
Author(s):  
Russell K. Karls ◽  
Jacqueline Brooks ◽  
Peter Rossmeissl ◽  
Janelle Luedke ◽  
Timothy J. Donohue
Keyword(s):  
Heat Shock ◽  
Temperature Profile ◽  
Rhodobacter Sphaeroides ◽  
Growth Temperature ◽  
Heat Shock Response ◽  
Anaerobic Respiration ◽  
Wild Type ◽  
Lower Growth ◽  
E Coli ◽  
Shock Response

ABSTRACT We report the role of a gene (rpoH) from the facultative phototroph Rhodobacter sphaeroides that encodes a protein (ς37) similar to Escherichia coliς32 and other members of the heat shock family of eubacterial sigma factors. R. sphaeroides ς37controls genes that function during environmental stress, since anR. sphaeroides ΔRpoH mutant is ∼30-fold more sensitive to the toxic oxyanion tellurite than wild-type cells. However, the ΔRpoH mutant lacks several phenotypes characteristic of E. coli cells lacking ς32. For example, anR. sphaeroides ΔRpoH mutant is not generally defective in phage morphogenesis, since it plates the lytic virus RS1, as well as its wild-type parent. In characterizing the response ofR. sphaeroides to heat, we found that its growth temperature profile is different when cells generate energy by aerobic respiration, anaerobic respiration, or photosynthesis. However, growth of the ΔRpoH mutant is comparable to that of a wild-type strain under each of these conditions. The ΔRpoH mutant mounted a heat shock response when aerobically grown cells were shifted from 30 to 42°C, but it exhibited altered induction kinetics of ∼120-, 85-, 75-, and 65-kDa proteins. There was also reduced accumulation of several presumed heat shock transcripts (rpoD PHS,groESL 1, etc.) when aerobically grown ΔRpoH cells were placed at 42°C. Under aerobic conditions, it appears that another sigma factor enables the ΔRpoH mutant to mount a heat shock response, since either RNA polymerase preparations from an ΔRpoH mutant, reconstituted Eς37, or a holoenzyme containing a 38-kDa protein (ς38) each transcribed E. coliEς32-dependent promoters. The lower growth temperature profile of photosynthetic cells is correlated with a difference in heat-inducible gene expression, since neither wild-type cells or the ΔRpoH mutant mount a typical heat shock response after such cultures were shifted from 30 to 37°C.

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