scholarly journals Robust Heat Shock Response in Chlamydia Lacking a Typical Heat Shock Sigma Factor

2022 ◽  
Vol 12 ◽  
Author(s):  
Yehong Huang ◽  
Wurihan Wurihan ◽  
Bin Lu ◽  
Yi Zou ◽  
Yuxuan Wang ◽  
...  
Keyword(s):  
Protein Synthesis ◽  
Heat Shock ◽  
Heat Shock Response ◽  
Sigma Factor ◽  
Target Genes ◽  
Sigma Factors ◽  
Survival Strategies ◽  
Alternative Sigma Factor ◽  
Metabolism Enzymes ◽  
Shock Response

Cells reprogram their transcriptome in response to stress, such as heat shock. In free-living bacteria, the transcriptomic reprogramming is mediated by increased DNA-binding activity of heat shock sigma factors and activation of genes normally repressed by heat-induced transcription factors. In this study, we performed transcriptomic analyses to investigate heat shock response in the obligate intracellular bacterium Chlamydia trachomatis, whose genome encodes only three sigma factors and a single heat-induced transcription factor. Nearly one-third of C. trachomatis genes showed statistically significant (≥1.5-fold) expression changes 30 min after shifting from 37 to 45°C. Notably, chromosomal genes encoding chaperones, energy metabolism enzymes, type III secretion proteins, as well as most plasmid-encoded genes, were differentially upregulated. In contrast, genes with functions in protein synthesis were disproportionately downregulated. These findings suggest that facilitating protein folding, increasing energy production, manipulating host activities, upregulating plasmid-encoded gene expression, and decreasing general protein synthesis helps facilitate C. trachomatis survival under stress. In addition to relieving negative regulation by the heat-inducible transcriptional repressor HrcA, heat shock upregulated the chlamydial primary sigma factor σ66 and an alternative sigma factor σ28. Interestingly, we show for the first time that heat shock downregulates the other alternative sigma factor σ54 in a bacterium. Downregulation of σ54 was accompanied by increased expression of the σ54 RNA polymerase activator AtoC, thus suggesting a unique regulatory mechanism for reestablishing normal expression of select σ54 target genes. Taken together, our findings reveal that C. trachomatis utilizes multiple novel survival strategies to cope with environmental stress and even to replicate. Future strategies that can specifically target and disrupt Chlamydia’s heat shock response will likely be of therapeutic value.

Ubiquitin gene expression in Dictyostelium is induced by heat and cold shock, cadmium, and inhibitors of protein synthesis

1988 ◽  
Vol 90 (1) ◽  
pp. 51-58 ◽  
Author(s):  
A. Muller-Taubenberger ◽  
J. Hagmann ◽  
A. Noegel ◽  
G. Gerisch
Keyword(s):  
Gene Expression ◽  
Protein Synthesis ◽  
Heat Shock ◽  
Differential Expression ◽  
Dictyostelium Discoideum ◽  
Heat Shock Response ◽  
Cold Shock ◽  
Multifunctional Protein ◽  
Cadmium Treatment ◽  
Shock Response

Ubiquitin is a highly conserved, multifunctional protein, which is implicated in the heat-shock response of eukaryotes. The differential expression of the multiple ubiquitin genes in Dictyostelium discoideum was investigated under various stress conditions. Growing D. discoideum cells express four major ubiquitin transcripts of sizes varying from 0.6 to 1.9 kb. Upon heat shock three additional ubiquitin mRNAs of 0.9, 1.2 and 1.4 kb accumulate within 30 min. The same three transcripts are expressed in response to cold shock or cadmium treatment. Inhibition of protein synthesis by cycloheximide leads to a particularly strong accumulation of the larger ubiquitin transcripts, which code for polyubiquitins. Possible mechanisms regulating the expression of ubiquitin transcripts upon heat shock and other stresses are discussed.

scholarly journals Heat-shock protein expression is absent in the antarctic fish Trematomus bernacchii (family Nototheniidae)

2000 ◽  
Vol 203 (15) ◽  
pp. 2331-2339 ◽  
Author(s):  
G.E. Hofmann ◽  
B.A. Buckley ◽  
S. Airaksinen ◽  
J.E. Keen ◽  
G.N. Somero
Keyword(s):  
Protein Synthesis ◽  
Heat Shock ◽  
Heat Shock Protein ◽  
Heat Shock Response ◽  
Solid Phase ◽  
Antarctic Fish ◽  
Shock Response ◽  
Enhanced Expression ◽  
Trematomus Bernacchii

The heat-shock response, the enhanced expression of one or more classes of molecular chaperones termed heat-shock proteins (hsps) in response to stress induced by high temperatures, is commonly viewed as a ‘universal’ characteristic of organisms. We examined the occurrence of the heat-shock response in a highly cold-adapted, stenothermal Antarctic teleost fish, Trematomus bernacchii, to determine whether this response has persisted in a lineage that has encountered very low and stable temperatures for at least the past 14–25 million years. The patterns of protein synthesis observed in in vivo metabolic labelling experiments that involved injection of (35)S-labelled methionine and cysteine into whole fish previously subjected to a heat stress of 10 degrees C yielded no evidence for synthesis of any size class of heat-shock protein. Parallel in vivo labelling experiments with isolated hepatocytes similarly showed significant amounts of protein synthesis, but no indication of enhanced expression of any class of hsp. The heavy metal cadmium, which is known to induce synthesis of hsps, also failed to alter the pattern of proteins synthesized in hepatocytes. Although stress-induced chaperones could not be detected under any of the experimental condition used, solid-phase antibody (western) analysis revealed that a constitutively expressed 70 kDa chaperone was present in this species, as predicted on the basis of requirements for chaperoning during protein synthesis. Amounts of the constitutively expressed 70 kDa chaperone increased in brain, but not in gill, during 22 days of acclimation to 5 degrees C. The apparent absence of a heat-shock response in this highly stenothermal species is interpreted as an indication that a physiological capacity observed in almost all other organisms has been lost as a result of the absence of positive selection during evolution at stable sub-zero temperatures. Whether the loss of the heat-shock response is due to dysfunctional genes for inducible hsps (loss of open reading frames or functional regulatory regions), unstable messenger RNAs, the absence of a functional heat-shock factor or some other lesion remains to be determined.

scholarly journals Increased Mistranslation ProtectsE. colifrom Protein Misfolding Stress due to Activation of a RpoS-dependent Heat Shock Response

2019 ◽  
Author(s):  
Christopher R. Evans ◽  
Yongqiang Fan ◽  
Jiqiang Ling
Keyword(s):  
Escherichia Coli ◽  
Protein Synthesis ◽  
Heat Shock ◽  
Sigma Factor ◽  
Protein Misfolding ◽  
Protective Function ◽  
General Stress Response ◽  
Shock Response ◽  
Sigma Factor Rpos

AbstractThe misincorporation of an incorrect amino acid into a polypeptide during protein synthesis is considered a detrimental phenomenon. Mistranslated protein is often misfolded and degraded or non-functional and results in an increased cost to quality control machinery. Despite these costs, errors during protein synthesis are common in bacteria. Here we report that increased rates of mistranslation inEscherichia coliprovide protection from protein misfolding stress by increasing the level of the heat shock sigma factor, RpoH. Surprisingly, this increase in RpoH due to mistranslation is dependent on the presence of the general stress response sigma factor, RpoS. This report provides evidence for a protective function of mistranslation and suggests a novel regulatory role of RpoS on the RpoH-activated heat shock.

scholarly journals Genetic differences in the duration of the lymphocyte heat shock response in mice.

Genetics ◽  
1990 ◽  
Vol 124 (4) ◽  
pp. 949-955
Author(s):  
V K Mohl ◽  
G D Bennett ◽  
R H Finnell
Keyword(s):  
Protein Synthesis ◽  
Heat Shock ◽  
Heat Shock Response ◽  
Mouse Strains ◽  
Adult Mice ◽  
Shock Response ◽  
Increased Sensitivity ◽  
Shock Proteins ◽  
The Relationship

Abstract Lymphocytes from adult mice bearing a known difference in genetic susceptibility to teratogen-induced exencephaly (SWV/SD, and DBA/2J) were evaluated for changes in protein synthesis following an in vivo heat treatment. Particular attention was paid to changes indicative of the heat shock response, a highly conserved response to environmental insult consisting of induction of a few, highly conserved proteins with simultaneous decreases in normal protein synthesis. The duration of heat shock protein induction in lymphocytes was found to be increased by 1 hr in the teratogen-sensitive SWV/SD strain as compared to the resistant DBA/2J strain. Densitometric analysis revealed a significant decrease in the relative synthesis of at least two non-heat shock proteins (36 kD and 45 kD) in the SWV/SD lymphocytes as compared to DBA/2J cells. The increased sensitivity of protein synthesis to hyperthermia in the SWV/SD lymphocytes were lost in the F1 progeny of reciprocal crosses between SWV/SD and DBA/2J mouse strains. Sensitivity to hyperthermia-induced exencephaly is recessive to resistance in these crosses. The relationship between altered protein synthesis and teratogen susceptibility is discussed.

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.

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.

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