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.

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 Characterizing Gene Copy Number of Heat Shock Protein Gene Families in the Emerald Rockcod, Trematomus bernacchii

Genes ◽  
2020 ◽  
Vol 11 (8) ◽  
pp. 867
Author(s):  
Anthony D. Tercero ◽  
Sean P. Place
Keyword(s):  
Heat Shock ◽  
Gene Duplication ◽  
Heat Shock Proteins ◽  
Heat Shock Response ◽  
Copy Number ◽  
Gene Families ◽  
Gene Copy ◽  
Shock Response ◽  
Trematomus Bernacchii ◽  
Shock Proteins

The suborder Notothenioidae is comprised of Antarctic fishes, several of which have lost their ability to rapidly upregulate heat shock proteins in response to thermal stress, instead adopting a pattern of expression resembling constitutive genes. Given the cold-denaturing effect that sub-zero waters have on proteins, evolution in the Southern Ocean has likely selected for increased expression of molecular chaperones. These selective pressures may have also enabled retention of gene duplicates, bolstering quantitative output of cytosolic heat shock proteins (HSPs). Given that newly duplicated genes are under more relaxed selection, it is plausible that gene duplication enabled altered regulation of such highly conserved genes. To test for evidence of gene duplication, copy number of various isoforms within major heat shock gene families were characterized via qPCR and compared between the Antarctic notothen, Trematomus bernacchii, which lost the inducible heat shock response, and the non-Antarctic notothen, Notothenia angustata, which maintains an inducible heat shock response. The results indicate duplication of isoforms within the hsp70 and hsp40 super families have occurred in the genome of T. bernacchii. The findings suggest gene duplications may have been critical in maintaining protein folding efficiency in the sub-zero waters and provided an evolutionary mechanism of alternative regulation of these conserved gene families.

Physical Activity, Muscle, and the HSP70 Response

1998 ◽  
Vol 23 (3) ◽  
pp. 245-260 ◽  
Author(s):  
J. Lon Kilgore ◽  
Timothy I. Musch ◽  
Christopher R. Ross
Keyword(s):  
Physical Activity ◽  
Heat Shock ◽  
Heat Shock Proteins ◽  
Heat Shock Protein ◽  
Heat Shock Response ◽  
Shock Response ◽  
Potential Applications ◽  
Shock Proteins ◽  
External Stimuli ◽  
Exercise And Training

Selye (1936) described how organisms react to various external stimuli (i.e., stressors). These reactions generally follow a programmed series of events and help the organism adapt to the imposed stress. The heat shock response is a common cellular reaction to external stressors, including physical activity. A characteristic set of proteins is synthesised shortly after the organism is exposed to stress. Researchers have not determined how heat shock proteins affect the exercise response. However, their role in adaptation to exercise and training might he inferred, since the synthetic patterns correlate well with the stress adaptation syndrome that Selye described. This review addresses the 70 kilodalton heat shock protein family (HSP70), the most strongly induced heat shock proteins. This paper provides an overview of the general heat shock response and a brief review of literature on HSP70 function, structure, regulation, and potential applications. Potential applications in health, exercise, and medicine are provided. Key words: heat shock, protein, exercise

Heat shock proteins affect RNA processing during the heat shock response of Saccharomyces cerevisiae

1991 ◽  
Vol 11 (2) ◽  
pp. 1062-1068
Author(s):  
H J Yost ◽  
S Lindquist
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Protein Synthesis ◽  
Heat Shock ◽  
Heat Shock Proteins ◽  
Heat Shock Response ◽  
Rna Splicing ◽  
Yeast Cells ◽  
Yeast Saccharomyces Cerevisiae ◽  
Shock Response ◽  
Shock Proteins

In the yeast Saccharomyces cerevisiae, the splicing of mRNA precursors is disrupted by a severe heat shock. Mild heat treatments prior to severe heat shock protect splicing from disruption, as was previously reported for Drosophila melanogaster. In contrast to D. melanogaster, protein synthesis during the pretreatment is not required to protect splicing in yeast cells. However, protein synthesis is required for the rapid recovery of splicing once it has been disrupted by a sudden severe heat shock. Mutations in two classes of yeast hsp genes affect the pattern of RNA splicing during the heat shock response. First, certain hsp70 mutants, which overproduce other heat shock proteins at normal temperatures, show constitutive protection of splicing at high temperatures and do not require pretreatment. Second, in hsp104 mutants, the recovery of RNA splicing after a severe heat shock is delayed compared with wild-type cells. These results indicate a greater degree of specialization in the protective functions of hsps than has previously been suspected. Some of the proteins (e.g., members of the hsp70 and hsp82 gene families) help to maintain normal cellular processes at higher temperatures. The particular function of hsp104, at least in splicing, is to facilitate recovery of the process once it has been disrupted.

Activation of HSF and selective increase in heat-shock proteins by acute dexamethasone treatment

2000 ◽  
Vol 278 (4) ◽  
pp. H1091-H1097 ◽  
Author(s):  
L. Sun ◽  
J. Chang ◽  
S. R. Kirchhoff ◽  
A. A. Knowlton
Keyword(s):  
Heat Shock ◽  
Heat Shock Proteins ◽  
Heat Shock Response ◽  
Cardiac Myocyte ◽  
Adult Rat ◽  
Shock Response ◽  
Cytokine Tumor Necrosis Factor ◽  
Factor Α ◽  
Shock Proteins ◽  
Selective Increase

Heat-shock proteins (HSPs) are an important family of endogenous protective proteins, which increase in response to myocardial ischemia and other stresses. Overexpression of HSP72 is cardioprotective. We were interested in the regulation of heat-shock factor (HSF), the transcription factor for HSP genes. Previously we have observed that the inflammatory cytokine tumor necrosis factor-α increases HSP72 levels and postulated that dexamethasone might effect the heat shock response. In the adult rat cardiac myocyte we found that treatment with either low (10 μM)- or high (100 μM)-dose dexamethasone activated HSF by 2–6 h as determined by gel shift assay without evidence of cytotoxicity. Although HSF activation is a key step in expression of HSP72, this may not result in an increase in HSP72. We found that 10 μM dexamethasone increased HSP72 38%, and 100 μM dexamethasone increased HSP72 62% ( P < 0.05). HSP27 and HSP60 were unchanged. The selective increase in HSP72 was associated with protection of the cardiac myocytes from hypoxia and reoxygenation. We conclude that dexamethasone is a novel inducer of the heat shock response.

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.

Heat-shock response in Legionella pneumophila

1988 ◽  
Vol 34 (10) ◽  
pp. 1148-1153 ◽  
Author(s):  
Michael W. Lema ◽  
Arnold Brown ◽  
Charles A. Butler ◽  
Paul S. Hoffman
Keyword(s):  
Heat Shock ◽  
Heat Shock Proteins ◽  
Legionella Pneumophila ◽  
Heat Shock Response ◽  
Temperature Shift ◽  
Bacterial Cells ◽  
Groel Protein ◽  
Shock Response ◽  
Molecular Masses ◽  
Shock Proteins

The heat-shock response of Legionella pneumophila was examined by radiolabelling bacterial cell proteins with [35S]methionine following a temperature shift from 30 to 42 °C. Five heat-shock proteins were identified as having molecular masses of 17, 60, 70, 78, and 85 kilodaltons (kDa). The 85- and 60-kDa proteins were equally distributed between supernatant and pellet fractions following ultracentrifugation at 100 000 × g, the 70- and 78-kDa proteins were found primarily in the supernatant, and the 17-kDa protein was found primarily in the pellet. Synthesis of subsets of the heat-shock proteins could be stimulated by novobiocin, patulin, or puromycin. Ethanol, an effector of the heat-shock response in other microorganisms, had little effect on L. pneumophila, even at the highest concentration tolerated by the bacterial cells (1.9%). Finally, the 60-kDa heat-shock protein of L. pneumophila was immunologically cross-reactive with a polyclonal antibody prepared to the Escherichia coli groEL protein. However, a mouse monoclonal antibody reactive with the 60-kDa protein of all legionellae tested did not cross-react with the E. coli groEL protein, suggesting that the Legionella 60-kDa protein contains common and unique epitopes.

Sign in / Sign up

Export Citation Format

Share Document