scholarly journals Cooperative Regulation of Campylobacter jejuni Heat-Shock Genes by HspR and HrcA

2020 ◽  
Vol 8 (8) ◽  
pp. 1161
Author(s):  
Marta Palombo ◽  
Vincenzo Scarlato ◽  
Davide Roncarati
Keyword(s):  
Heat Shock ◽  
Dna Binding ◽  
Campylobacter Jejuni ◽  
Heat Shock Response ◽  
Inverted Repeat ◽  
Regulatory Function ◽  
Heat Shock Genes ◽  
Repressive Effect ◽  
Shock Response ◽  
Regulated Promoters

The heat-shock response is defined by the transient gene-expression program that leads to the rapid accumulation of heat-shock proteins. This evolutionary conserved response aims at the preservation of the intracellular environment and represents a crucial pathway during the establishment of host–pathogen interaction. In the food-borne pathogen Campylobacter jejuni two transcriptional repressors, named HspR and HrcA, are involved in the regulation of the major heat-shock genes. However, the molecular mechanism underpinning HspR and HrcA regulatory function has not been defined yet. In the present work, we assayed and mapped the HspR and HrcA interactions on heat-shock promoters by high-resolution DNase I footprintings, defining their regulatory circuit, which governs C. jejuni heat-shock response. We found that, while DNA-binding of HrcA covers a compact region enclosing a single inverted repeat similar to the so-called Controlling Inverted Repeat of Chaperone Expression (CIRCE) sequence, HspR interacts with multiple high- and low-affinity binding sites, which contain HspR Associated Inverted Repeat (HAIR)-like sequences. We also explored the DNA-binding properties of the two repressors competitively on their common targets and observed, for the first time, that HrcA and HspR can directly interact and their binding on co-regulated promoters occurs in a cooperative manner. This mutual cooperative mechanism of DNA binding could explain the synergic repressive effect of HspR and HrcA observed in vivo on co-regulated promoters. Peculiarities of the molecular mechanisms exerted by HspR and HrcA in C. jejuni are compared to the closely related bacterium H. pylori that uses homologues of the two regulators.

scholarly journals The hrcA and hspR regulons of Campylobacter jejuni

Microbiology ◽  
2010 ◽  
Vol 156 (1) ◽  
pp. 158-166 ◽  
Author(s):  
Christopher W. Holmes ◽  
Charles W. Penn ◽  
Peter A. Lund
Keyword(s):  
Gene Expression ◽  
Heat Shock ◽  
Campylobacter Jejuni ◽  
Growth Temperature ◽  
Heat Shock Response ◽  
Human Pathogen ◽  
Response Regulators ◽  
Heat Shock Genes ◽  
Shock Response ◽  
Number Of Genes

The human pathogen Campylobacter jejuni has a classic heat shock response, showing induction of chaperones and proteases plus several unidentified proteins in response to a small increase in growth temperature. The genome contains two homologues to known heat shock response regulators, HrcA and HspR. Previous work has shown that HspR controls several heat-shock genes, but the hrcA regulon has not been defined. We have constructed single and double deletions of C. jejuni hrcA and hspR and analysed gene expression using microarrays. Only a small number of genes are controlled by these two regulators, and the two regulons overlap. Strains mutated in hspR, but not those mutated in hrcA, showed enhanced thermotolerance. Some genes previously identified as being downregulated in a strain lacking hspR showed no change in expression in our experiments.

scholarly journals Feeling the Heat: The Campylobacter jejuni HrcA Transcriptional Repressor Is an Intrinsic Protein Thermosensor

Biomolecules ◽  
2021 ◽  
Vol 11 (10) ◽  
pp. 1413
Author(s):  
Giovanni Versace ◽  
Marta Palombo ◽  
Anna Menon ◽  
Vincenzo Scarlato ◽  
Davide Roncarati
Keyword(s):  
Heat Stress ◽  
Heat Shock ◽  
Dna Binding ◽  
Campylobacter Jejuni ◽  
Heat Shock Response ◽  
Binding Activity ◽  
Protective Mechanism ◽  
Intrinsic Protein ◽  
Dna Binding Activity ◽  
Shock Response

The heat-shock response, a universal protective mechanism consisting of a transcriptional reprogramming of the cellular transcriptome, results in the accumulation of proteins which counteract the deleterious effects of heat-stress on cellular polypeptides. To quickly respond to thermal stress and trigger the heat-shock response, bacteria rely on different mechanisms to detect temperature variations, which can involve nearly all classes of biological molecules. In Campylobacter jejuni the response to heat-shock is transcriptionally controlled by a regulatory circuit involving two repressors, HspR and HrcA. In the present work we show that the heat-shock repressor HrcA acts as an intrinsic protein thermometer. We report that a temperature upshift up to 42°C negatively affects HrcA DNA-binding activity to a target promoter, a condition required for de-repression of regulated genes. Furthermore, we show that this impairment of HrcA binding at 42°C is irreversible in vitro, as DNA-binding was still not restored by reversing the incubation temperature to 37°C. On the other hand, we demonstrate that the DNA-binding activity of HspR, which controls, in combination with HrcA, the transcription of chaperones’ genes, is unaffected by heat-stress up to 45°C, portraying this master repressor as a rather stable protein. Additionally, we show that HrcA binding activity is enhanced by the chaperonin GroE, upon direct protein–protein interaction. In conclusion, the results presented in this work establish HrcA as a novel example of intrinsic heat-sensing transcriptional regulator, whose DNA-binding activity is positively modulated by the GroE chaperonin.

Mitochondrial activity and heat-shock response during morphogenesis in the pathogenic fungus Histoplasma capsulatum

1992 ◽  
Vol 70 (3-4) ◽  
pp. 207-214 ◽  
Author(s):  
Eduardo J. Patriarca ◽  
George S. Kobayashi ◽  
Bruno Maresca
Keyword(s):  
Heat Shock ◽  
Heat Shock Response ◽  
Elevated Temperatures ◽  
Histoplasma Capsulatum ◽  
Pathogenic Fungus ◽  
Temperature Shift ◽  
Mitochondrial Activity ◽  
Mitochondrial Atpase ◽  
Heat Shock Genes ◽  
Shock Response

Changes in temperature and a variety of other stimuli coordinately induce transcription of a specific set of heat-shock genes in all organisms. In the human fungal pathogen Histoplasma capsulatum, a temperature shift from 25 to 37 °C acts not only as a signal that causes transcription of heat-shock genes, but also triggers a morphological mycelium-to yeast-phase transition. The temperature-induced morphological transition may be viewed as a heat-shock response followed by cellular adaptation to a higher temperature. We have found that by inducing thermotolerance, i.e., an initial incubation at 34 °C, the thermosensitive attenuated Downs strain of H. capsulatum can be made to resemble those of the more temperature-tolerant G222B strain with respect to mitochondrial ATPase activity and electron transport efficiency at elevated temperatures. Furthermore, if the heat-shock response is first elicited by preincubation at milder temperatures or stress, transcription of heat-shock mRNA in mycelial cells of Downs strain that shifted to 37 °C proceeds at rates comparable to those of the virulent strains.Key words: heat shock, thermotolerance, ATPase, 70-kilodalton heat-shock protein, fungal morphogenesis.

scholarly journals Regulation of heat shock factor in Schizosaccharomyces pombe more closely resembles regulation in mammals than in Saccharomyces cerevisiae.

1991 ◽  
Vol 11 (1) ◽  
pp. 281-288 ◽  
Author(s):  
G J Gallo ◽  
T J Schuetz ◽  
R E Kingston
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Heat Shock ◽  
Dna Binding ◽  
Schizosaccharomyces Pombe ◽  
Fission Yeast ◽  
Heat Shock Response ◽  
Heat Shock Factor ◽  
Regulatory Sequence ◽  
Heat Shock Element ◽  
Shock Response

The heat shock response appears to be universal. All eucaryotes studied encode a protein, heat shock factor (HSF), that is believed to regulate transcription of heat shock genes. This protein binds to a regulatory sequence, the heat shock element, that is absolutely conserved among eucaryotes. We report here the identification of HSF in the fission yeast Schizosaccharomyces pombe. HSF binding was not observed in extracts from normally growing S. pombe (28 degrees C) but was detected in increasing amounts as the temperature of heat shock increased between 39 and 45 degrees C. This regulation is in contrast to that observed in Saccharomyces cerevisiae, in which HSF binding is detectable at both normal and heat shock temperatures. The S. pombe factor bound specifically to the heat shock element, as judged by methylation interference and DNase I protection analysis. The induction of S. pombe HSF was not inhibited by cycloheximide, suggesting that induction occurs posttranslationally, and the induced factor was shown to be phosphorylated. S. pombe HSF was purified to near homogeneity and was shown to have an apparent mobility of approximately 108 kDa. Since heat-induced DNA binding by HSF had previously been demonstrated only in metazoans, the conservation of heat-induced DNA binding by HSF among S. pombe and metazoans suggests that this mode of regulation is evolutionarily ancient.

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 Heat Shock Response of Archaeoglobus fulgidus

2005 ◽  
Vol 187 (17) ◽  
pp. 6046-6057 ◽  
Author(s):  
Lars Rohlin ◽  
Jonathan D. Trent ◽  
Kirsty Salmon ◽  
Unmi Kim ◽  
Robert P. Gunsalus ◽  
...  
Keyword(s):  
Heat Shock ◽  
Dna Binding ◽  
Heat Shock Response ◽  
Expression Profiles ◽  
Small Heat Shock Protein ◽  
Transcript Abundance ◽  
Archaeoglobus Fulgidus ◽  
Binding Motif ◽  
Cell Functions ◽  
Shock Response

ABSTRACT The heat shock response of the hyperthermophilic archaeon Archaeoglobus fulgidus strain VC-16 was studied using whole-genome microarrays. On the basis of the resulting expression profiles, approximately 350 of the 2,410 open reading frames (ORFs) (ca. 14%) exhibited increased or decreased transcript abundance. These span a range of cell functions, including energy production, amino acid metabolism, and signal transduction, where the majority are uncharacterized. One ORF called AF1298 was identified that contains a putative helix-turn-helix DNA binding motif. The gene product, HSR1, was expressed and purified from Escherichia coli and was used to characterize specific DNA recognition regions upstream of two A. fulgidus genes, AF1298 and AF1971. The results indicate that AF1298 is autoregulated and is part of an operon with two downstream genes that encode a small heat shock protein, Hsp20, and cdc48, an AAA+ ATPase. The DNase I footprints using HSR1 suggest the presence of a cis-binding motif upstream of AF1298 consisting of CTAAC-N5-GTTAG. Since AF1298 is negatively regulated in response to heat shock and encodes a protein only distantly related to the N-terminal DNA binding domain of Phr of Pyrococcus furiosus, these results suggest that HSR1 and Phr may belong to an evolutionarily diverse protein family involved in heat shock regulation in hyperthermophilic and mesophilic Archaea organisms.

scholarly journals Characterization of Campylobacter jejuni RacRS Reveals Roles in the Heat Shock Response, Motility, and Maintenance of Cell Length Homogeneity

2012 ◽  
Vol 194 (9) ◽  
pp. 2342-2354 ◽  
Author(s):  
D. Apel ◽  
J. Ellermeier ◽  
M. Pryjma ◽  
V. J. DiRita ◽  
E. C. Gaynor
Keyword(s):  
Heat Shock ◽  
Campylobacter Jejuni ◽  
Heat Shock Response ◽  
Cell Length ◽  
Shock Response

Diverse roles for HspR in Campylobacter jejuni revealed by the proteome, transcriptome and phenotypic characterization of an hspR mutant

Microbiology ◽  
2005 ◽  
Vol 151 (3) ◽  
pp. 905-915 ◽  
Author(s):  
Marianne Thorup Andersen ◽  
Lone Brøndsted ◽  
Bruce M. Pearson ◽  
Francis Mulholland ◽  
Mary Parker ◽  
...  
Keyword(s):  
Heat Shock ◽  
Campylobacter Jejuni ◽  
Heat Shock Response ◽  
Negative Regulator ◽  
Phenotypic Characterization ◽  
Heat Sensitivity ◽  
Altered Expression ◽  
Shock Response ◽  
Mutant Cells

Campylobacter jejuni is a leading cause of bacterial gastroenteritis in the developed world. The role of a homologue of the negative transcriptional regulatory protein HspR, which in other organisms participates in the control of the heat-shock response, was investigated. Following inactivation of hspR in C. jejuni, members of the HspR regulon were identified by DNA microarray transcript profiling. In agreement with the predicted role of HspR as a negative regulator of genes involved in the heat-shock response, it was observed that the transcript amounts of 13 genes were increased in the hspR mutant, including the chaperone genes dnaK, grpE and clpB, and a gene encoding the heat-shock regulator HrcA. Proteomic analysis also revealed increased synthesis of the heat-shock proteins DnaK, GrpE, GroEL and GroES in the absence of HspR. The altered expression of chaperones was accompanied by heat sensitivity, as the hspR mutant was unable to form colonies at 44 °C. Surprisingly, transcriptome analysis also revealed a group of 17 genes with lower transcript levels in the hspR mutant. Of these, eight were predicted to be involved in the formation of the flagella apparatus, and the decreased expression is likely to be responsible for the reduced motility and ability to autoagglutinate that was observed for hspR mutant cells. Electron micrographs showed that mutant cells were spiral-shaped and carried intact flagella, but were elongated compared to wild-type cells. The inactivation of hspR also reduced the ability of Campylobacter to adhere to and invade human epithelial INT-407 cells in vitro, possibly as a consequence of the reduced motility or lower expression of the flagellar export apparatus in hspR mutant cells. It was concluded that, in C. jejuni, HspR influences the expression of several genes that are likely to have an impact on the ability of the bacterium to successfully survive in food products and subsequently infect the consumer.

The heat shock response in transgenic plants: the use of chimaeric heat shock genes

1992 ◽  
pp. 247-266 ◽  
Author(s):  
F. Schöffl ◽  
V. Diedring ◽  
M. Kliem ◽  
M. Rieping ◽  
G. Schröder ◽  
...  
Keyword(s):  
Heat Shock ◽  
Transgenic Plants ◽  
Heat Shock Response ◽  
Heat Shock Genes ◽  
Shock Response

Genetic analysis of heat shock response in three Drosophila species of the obscura group

Genome ◽  
1992 ◽  
Vol 35 (5) ◽  
pp. 870-880 ◽  
Author(s):  
M. Dolores Moltó ◽  
Luis Pascual ◽  
M. José Martínez-Sebastián ◽  
Rosa de Frutos
Keyword(s):  
Heat Shock ◽  
Heat Shock Response ◽  
Single Copy ◽  
Drosophila Species ◽  
Heat Shock Genes ◽  
Evolutionary Changes ◽  
Shock Response ◽  
Shock Proteins ◽  
Group Species ◽  
Obscura Group

Heat shock response was investigated in three species of the obscura group of the Drosophila genus (D. subobscura, D. guanche, and D. madeirensis) by chromosome cytology analysis and [3H]uridine labeling. A set of eight puffs (2C, 15DE, 18C, 27A, 31CD, 85AB, 89A, and 94A) were induced after heat treatments in each of the three species; 18C, 27A, 89A, and 94A were the most heavily labeled in the autoradiograms after the induced conditions. From the in situ results using the major heat shock genes of D. melanogaster as a probe, it was inferred that the 18C, 94A, 89A, and 27A loci of the three obscura group species are homologous to D. melanogaster loci, which contain, HSP82, HSP70, HSP68, and HSPs encoding for the small heat shock proteins, respectively. When this organization was compared with that of D. melanogaster, fewer evolutionary changes, mainly gene duplications, were found to have occurred in the obscura group species than in the D. melanogaster group. In the three species analyzed in this work, as well as in the other Drosophila species studied, the heat shock genes are distributed on D and E Muller's elements, behaving as single copy genes that do not move around the genome.Key words: Drosophila, obscura group, polytene chromosome, heat shock.

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