Prevention of protein denaturation under heat stress by the chaperonin Hsp60

Aging exacerbates oxidative stress and liver fibrosis in an animal model of Down Syndrome

Down Syndrome (DS) is a common genetic disorder characterized by an extra copy of chromosome 21, leading to dysregulation of various metabolic pathways. Oxidative stress in DS is associated with neurodevelopmental defects, neuronal dysfunction, and a dementia onset resembling Alzheimer's disease. Additionally, chronic oxidative stress contributes to cardiovascular diseases and certain cancers prevalent in DS individuals. This study investigates the impact of ageing on oxidative stress and liver fibrosis using a DS murine model (Ts2Cje mice). Our results show that DS mice show increased liver oxidative stress and impaired antioxidant defenses, as evidenced by reduced glutathione levels and increased lipid peroxidation. Therefore, DS liver exhibits an altered inflammatory response and mitochondrial fitness as we showed by assaying the expression of HMOX1, CLPP, and the heat shock proteins Hsp90 and Hsp60. DS liver also displays dysregulated lipid metabolism, indicated by altered expression of PPARα, PPARγ, FATP5, and CTP2. Consistently, these changes might contribute to non-alcoholic fatty liver disease development, a condition characterized by liver fat accumulation. Consistently, histological analysis of DS liver reveals increased fibrosis and steatosis, as showed by Col1a1 increased expression, indicative of potential progression to liver cirrhosis. Therefore, our findings suggest an increased risk of liver pathologies in DS individuals, particularly when combined with the higher prevalence of obesity and metabolic dysfunctions in DS patients. These results shed a light on the liver's role in DS-associated pathologies and suggest potential therapeutic strategies targeting oxidative stress and lipid metabolism to prevent or mitigate liver-related complications in DS individuals.

Elevated external temperature affects cell ultrastructure and heat shock proteins (HSPs) in Paramacrobiotus experimentalis Kaczmarek, Mioduchowska, Poprawa, & Roszkowska, 2020

Increasing temperature influences the habitats of various organisms, including microscopic invertebrates. To gain insight into temperature-dependent changes in tardigrades, we isolated storage cells exposed to various temperatures and conducted biochemical and ultrastructural analysis in active and tun-state Paramacrobiotus experimentalis Kaczmarek, Mioduchowska, Poprawa, & Roszkowska, 2020. The abundance of heat shock proteins (HSPs) and ultrastructure of the storage cells were examined at different temperatures (20 °C, 30 °C, 35 °C, 37 °C, 40 °C, and 42 °C) in storage cells isolated from active specimens of Pam. experimentalis. In the active animals, upon increase in external temperature, we observed an increase in the levels of HSPs (HSP27, HSP60, and HSP70). Furthermore, the number of ultrastructural changes in storage cells increased with increasing temperature. Cellular organelles, such as mitochondria and the rough endoplasmic reticulum, gradually degenerated. At 42 °C, cell death occurred by necrosis. Apart from the higher electron density of the karyoplasm and the accumulation of electron-dense material in some mitochondria (at 42 °C), almost no changes were observed in the ultrastructure of tun storage cells exposed to different temperatures. We concluded that desiccated (tun-state) are resistant to high temperatures, but not active tardigrades (survival rates of tuns after 24 h of rehydration: 93.3% at 20 °C, 60.0% at 35 °C, 33.3% at 37 °C, 33.3% at 40 °C, and 20.0% at 42 °C).

The interspecific variations in molecular responses to various doses of heat and cold stress: the case of cereal aphids

Insects are currently subjected to unprecedented thermal stress due to recent increases in the frequency and amplitude of temperature extremes. Understanding molecular responses to thermal stress is critically important to appreciate how species react to thermal stress. Three co-occurring cosmopolitan species are found within the guild of cereal aphids: Sitobion avenae, Ropalosiphum padi and Metopolophium dirhodum. Earlier reports have shown that increasing frequency of temperature extremes causes a shift in dominant species within guilds of cereal aphids by differently altering the population's growth. We hypothesize that a differential molecular response to stress among species may partially explain these changes. Heat shock proteins (HSPs) are molecular chaperones well known to play an important role in protecting against the adverse effects of thermal stress. However, few studies on molecular chaperones have been conducted in cereal aphids. In this study, we compared the heat and cold tolerance between three aphid species by measuring the median lethal time (Lt₅₀) and examined the expression profiles of seven hsp genes after exposures to comparable thermal injury levels and also after same exposure durations. Results showed that R. padi survived comparatively better at high temperatures than the two other species but was more cold-sensitive. Hsp genes were induced more strongly by heat than cold stress. Hsp70A was the most strongly up-regulated gene in response to both heat and cold stress. R. padi had more heat inducible genes and significantly higher mRNA levels of hsp70A, hsp10, hsp60 and hsp90 than the other two species. Hsps ceased to be expressed at 37°C in M. dirhodum and S. avenae while expression was maintained in R. padi. In contrast, M. dirhodum was more cold tolerant and had more cold inducible genes than the others. These results confirm species-specific differences in molecular stress responses and suggest that differences in induced expression of hsps may be related to species' thermal tolerance, thus causing the changes in the relative abundance.

Loss of mitochondrial performance at high temperatures is correlated with upper thermal tolerance among populations of an intertidal copepod

Environmental temperatures have pervasive effects on the performance and tolerance of ectothermic organisms, and thermal tolerance limits likely play key roles underlying biogeographic ranges and responses to environmental change. Mitochondria are central to metabolic processes in eukaryotic cells, and these metabolic functions are thermally sensitive; however, potential relationships between mitochondrial function, thermal tolerance limits and local thermal adaptation in general remain unresolved. Loss of ATP synthesis capacity at high temperatures has recently been suggested as a mechanistic link between mitochondrial function and upper thermal tolerance limits. Here we use a common-garden experiment with seven locally adapted populations of intertidal copepods (Tigriopus californicus), spanning approximately 21.5° latitude, to assess genetically based variation in the thermal performance curves of maximal ATP synthesis rates in isolated mitochondria. These thermal performance curves displayed substantial variation among populations with higher ATP synthesis rates at lower temperatures (20-25 °C) in northern populations than in southern populations. In contrast, mitochondria from southern populations maintained ATP synthesis rates at higher temperatures than the temperatures that caused loss of ATP synthesis capacity in mitochondria from northern populations. Additionally, there was a tight correlation between the thermal limits of ATP synthesis and previously determined variation in upper thermal tolerance limits among populations. This suggests that mitochondria may play an important role in latitudinal thermal adaptation in T. californicus, and supports the hypothesis that loss of mitochondrial performance at high temperatures is linked to whole-organism thermal tolerance limits in this ectotherm.

Key infection stages defending heat stress in high-temperature-resistant Blumeria graminis f. sp. tritici isolates

With the increase of temperature in the winter wheat-growing regions in China, the high-temperature-resistant Blumeria graminis f. sp. tritici (Bgt) isolates developed in the fields. To clarify the key infection stages and the roles of heat shock protein (HSP) genes of high-temperature-resistant Bgt isolates defending high temperature, 3 high-temperature-resistant and 3 sensitive Bgt isolates were selected from 55 isolates after determination of temperature sensitivity. And then they were used to investigate the infection stages and the expression levels of HSP genes, including Bgthsp60, Bgthsp70, Bgthsp90, and Bgthsp104, at 18°C and 25°C. The formation frequency of abnormal appressoria and inhibition rate of haustoria formation of high-temperature-resistant isolates at 25°C were lower than those of high-temperature-sensitive isolates, while major axis of microcolonies of high-temperature-resistant isolates was higher than those of high-temperature-sensitive isolates at 25°C. The results indicated that haustoria formation and hyphal expansion were the key infection stages of defense against heat stress in high-temperature-resistant isolates. Further analyses of HSP genes found the expression levels of Bgthsp60 and Bgthsp70c were upregulated at 24 and 72 h post-inoculation in high-temperature-resistant isolates, while no significant difference was observed for Bgthsp90 and Bgthsp104 genes. Taken together, the basis of high-temperature-resistant Bgt isolates is associated with induced expression of Bgthsp60 and Bgthsp70c response to heat stress in haustoria formation and hyphal expansion stages.

Thermal stress and mutation accumulation increase heat shock protein expression in Daphnia

Understanding the short- and long-term consequences of climate change is a major challenge in biology. For aquatic organisms, temperature changes and drought can lead to thermal stress and habitat loss, both of which can ultimately lead to higher mutation rates. Here, we examine the effect of high temperature and mutation accumulation on gene expression at two loci from the heat shock protein (HSP) gene family, HSP60 and HSP90. HSPs have been posited to serve as 'mutational capacitors' given their role as molecular chaperones involved in protein folding and degradation, thus buffering against a wide range of cellular stress and destabilization. We assayed changes in HSP expression across 5 genotypes of Daphnia magna, a sentinel species in ecology and environmental biology, with and without acute exposure to thermal stress and accumulated mutations. Across genotypes, HSP expression increased ~ 6× in response to heat and ~ 4× with mutation accumulation, individually. Both factors simultaneously (lineages with high mutation loads exposed to high heat) increased gene expression ~ 23×-much more than that predicted by an additive model. Our results corroborate suggestions that HSPs can buffer against not only the effects of heat, but also mutations-a combination of factors both likely to increase in a warming world.

Supplementary Information

The online version contains supplementary material available at 10.1007/s10682-022-10209-1.

Genome-wide analysis and characterization of heat shock transcription factors (Hsfs) in common bean (Phaseolus vulgaris L.)

Heat shock transcription factors (Hsfs) play an essential role as transcriptional regulatory proteins against heat stress by controlling the expression of heat-responsive genes. Common bean is a highly thermosensitive crop, and, therefore, its genome sequence information is segregated, characterized here in terms of heat shock transcription factors and its evolutionary significance. In this study, a complete comprehensive set of 29 non-redundant full-length Hsf genes were identified and characterized from Phaseolus vulgaris L. (PvHsf) genome sequence. Detailed gene information such as chromosomal localization, domain position, motif organization, and exon-intron identification were analyzed. All the 29 PvHsf genes were mapped on 8 out of 11 chromosomes, indicating the gene duplication occurred in the common bean genome. Motif analysis and exon-intron structure were conserved in each group, which showed that the cytoplasmic proteins highly influence the conserved structure of PvHsfs and heat-induced response. The HSF genes were grouped into three classes, i.e., A to C and 14 groups, based on structural features and phylogenetic relationships. Only one pair of paralog sequences suggests that it may be derived from the duplication event during evolution. A comparative genomics study indicated the influence of whole-genome duplication and purifying selection on the common bean genome during development. In silico expression analysis showed the active role of class A and B family during abiotic stress conditions and higher expression in floral organs. The qRT-PCR analysis revealed PvHSFA8 as the master regulator and PvHSFB1A and PvHSFB2A induction during heat exposure in French beans.

Molecular Bases of Heat Stress Responses in Vegetable Crops With Focusing on Heat Shock Factors and Heat Shock Proteins

The effects of the climate change including an increase in the average global temperatures, and abnormal weather events such as frequent and severe heatwaves are emerging as a worldwide ecological concern due to their impacts on plant vegetation and crop productivity. In this review, the molecular processes of plants in response to heat stress-from the sensing of heat stress, the subsequent molecular cascades associated with the activation of heat shock factors and their primary targets (heat shock proteins), to the cellular responses-have been summarized with an emphasis on the classification and functions of heat shock proteins. Vegetables contain many essential vitamins, minerals, antioxidants, and fibers that provide many critical health benefits to humans. The adverse effects of heat stress on vegetable growth can be alleviated by developing vegetable crops with enhanced thermotolerance with the aid of various genetic tools. To achieve this goal, a solid understanding of the molecular and/or cellular mechanisms underlying various responses of vegetables to high temperature is imperative. Therefore, efforts to identify heat stress-responsive genes including those that code for heat shock factors and heat shock proteins, their functional roles in vegetable crops, and also their application to developing vegetables tolerant to heat stress are discussed.

Evolutionary conservation of systemic and reversible amyloid aggregation

In response to environmental stress, human cells have been shown to form reversible amyloid aggregates within the nucleus, termed amyloid bodies (A-bodies). These protective physiological structures share many of the biophysical characteristics associated with the pathological amyloids found in Alzheimer's and Parkinson's disease. Here, we show that A-bodies are evolutionarily conserved across the eukaryotic domain, with their detection in Drosophila melanogaster and Saccharomyces cerevisiae marking the first examples of these functional amyloids being induced outside of a cultured cell setting. The conditions triggering amyloidogenesis varied significantly among the species tested, with results indicating that A-body formation is a severe, but sublethal, stress response pathway that is tailored to the environmental norms of an organism. RNA-sequencing analyses demonstrate that the regulatory low-complexity long non-coding RNAs that drive A-body aggregation are both conserved and essential in human, mouse and chicken cells. Thus, the identification of these natural and reversible functional amyloids in a variety of evolutionarily diverse species highlights the physiological significance of this protein conformation, and will be informative in advancing our understanding of both functional and pathological amyloid aggregation events. This article has an associated First Person interview with the first author of the paper.

A Simplistic Single-Step Method for Preparing Biomimetic Nanoparticles from Endogenous Biomaterials

Many works utilize products isolated from nature as capping agents to functionalize gold nanoparticles for targeting and therapeutic applications. Some of the most advanced of these strategies utilize complex multicomponent biomaterials, such as whole cell-membranes, for nanoparticle functionalization strategies for evading or initializing immune response as well as for targeting. Strategies like these, wherein whole cell membrane is utilized for functionalization, take advantage of the complexity of the protein-lipid content and organization, which cells normally use for communication and interaction (instilling these capacities to nanoparticle vectors). Many approaches for achieving this in functionalizing the surface of nanoparticles rely on multistep processes, which necessitate the addition and then removal of synthetic molecules, heating, or pH modifications. These processes can have deleterious modifying effects on the functionalizing biomolecules, resulting in loss of product and time during each purification step, as well as potentially changing the biomolecule functionality toward a nondesirable effect. Here, we describe methods for forming gold nanoparticles at room temperature in a single step, functionalized with proteins, using nicotinamide adenine dinucleotide (NADH). This process enables formation of nanoparticles that can be functionalized by individual proteins (demonstrated with FBS) or whole cells membrane (extracted from B16F10 cells). This work is derivative from observations found in the literature by us and others, that mammalian cells are capable of producing gold nanoparticles from ionic gold without the supplementation of chemical species. The products of this single-step synthesis described herein have been optimized to maintain biomolecule integrity and so that there are no further purification steps required. To characterize the nanoparticles in terms of their shape, size, surface functionality, and biomolecule integrity throughout development, we employed light-based spectroscopy techniques, molecular modeling, electron microscopy, light scattering, and gel electrophoresis techniques. In order to compare the optimized biomolecule-functionalized nanoparticles against current standards (which require synthetic linkers, heating, or pH manipulation), we employed metabolic and live/dead assays as well as light-based microscopy/spectroscopy in vitro. In comparing our synthetic process against others for forming gold nanoparticles functionalized with complex biomolecule components (whole-cell membrane), we found that this process had superior particle internalization. Our strategy has similar outlets for application to these other works, however, because this process is entirely reliant on endogenous biomaterials and has additional potential.

Chaperonin Abundance Enhances Bacterial Fitness

The ability of chaperonins to buffer mutations that affect protein folding pathways suggests that their abundance should be evolutionarily advantageous. Here, we investigate the effect of chaperonin overproduction on cellular fitness in Escherichia coli. We demonstrate that chaperonin abundance confers 1) an ability to tolerate higher temperatures, 2) improved cellular fitness, and 3) enhanced folding of metabolic enzymes, which is expected to lead to enhanced energy harvesting potential.

Label-Free Comparative Proteomics Analysis Revealed Heat Stress Responsive Mechanism in Hypsizygus marmoreus

Heat stress is an important adverse environmental stress that influences the growth and development of Hypsizygus marmoreus (white var.). However, the molecular basis of heat stress response in H. marmoreus remains poorly understood. In this study, label-free comparative proteomic technique was applied to investigate global protein expression profile of H. marmoreus mycelia under heat stress. Confocal laser scanning microscope observation revealed that mycelia underwent autolysis and apoptosis under heat stress. Autolysis was mediated by upregulating the expression of cell wall degradation enzymes and inhibiting cell wall synthesis enzymes, and apoptosis might be induced by ROS and activation of caspases. TBARS analysis indicated that ROS was accumulated in H. marmoreus mycelia under heat stress. H. marmoreus induced antioxidant defense system by upregulating the expression of catalases, superoxide dismutases and peroxidases to prevent oxidative damage. MAPK cascade was found to be involved in heat stress signal transduction. The stress signal induced a ubiquitous defense response: inducible expression of different kinds of heat shock proteins. Trehalose synthesis enzymes were also upregulated, suggesting the accumulation of stress protector trehalose under heat stress. Besides, upregulated proteasome was identified, which could prevented the accumulation of non-functional misfolding proteins. To satisfy ATP depletion in heat response cellular processes, such as ROS scavenging, and protein folding and synthesis, enzymes involved in energy production (carbon metabolism and ATP synthesis) system were upregulated under heat stress. Taken together, these findings improve our understanding of the molecular mechanisms underlying the response of heat stress in H. marmoreus.

Protein-caged zinc porphyrin as a carbonic anhydrase mimic for carbon dioxide capture

Zinc tetraphenylporphyrin (Zn-TPP) solubilized by GroEL protein cage was prepared as a supramolecular mimic of carbonic anhydrase (CA) for CO2 capture. It is shown that the soluble Zn-TPP-GroEL complex can be formed easily by detergent dialysis. The Zn-TPP/GroEL binding ratio was found to increase with their dialysis ratio until reaching the maximum of about 30 porphyrins per protein cage. Moreover, the complex showed hydrase activity that catalyzes the CO2 hydration in HCO3- and H+. It is further seen that the catalytic activity of Zn-TPP-GroEL was about one-half of that of a bovine CA at 25 °C. On the other hand, as the temperature was increased to 60 °C close to an industrial CO2 absorption temperature, the natural enzyme lost function while Zn-TPP-GroEL exhibited better catalytic performance indicative of a higher thermal stability. Finally, we demonstrate that the GroEL-solubilized Zn-TPP is able to accelerate the precipitation of CO2 in the form of CaCO3 and has better long-term performance than the bovine CA. Thus a new type of nano-caged system mimicking natural CAs for potential applications in carbon capture has been established.

Chronic heat stress regulates the relation between heat shock protein and immunity in broiler small intestine

Chronic heat stress is considered to decrease the immune functions which makes negative effect on broiler growth performance. Here, we investigated the relationship between chronic heat stress, growth performance, and immunity in the small intestine of broilers. The study included two groups (control and heat stressed group) with eight replications per group. Ten broilers of 20-day aged were allocated in each replication. On day 35, the treatment group was subdivided into two groups based on their body weights (heavy and low body weight). Although, there was only the control and treatment group on day 28. The growth performance decreased and expression of heat shock protein 70 (HSP70), HSP60, and HSP47 increased on days 28 and 35 in the chronic heat stress group as compared with those in the control group. The expression levels of HSPs were significantly higher in the low body weight group than in the control group. The genes HSP70 and HSP60 were significantly associated with pro- and anti-inflammatory cytokines in the small intestine of the broilers of the treatment group. Thus, HSP70 and HSP60 activated the adaptive immunity in the small intestines of the broilers from the treatment group to allow adaptation to chronic heat stress environment.

Acute Heat Stress Induces the Differential Expression of Heat Shock Proteins in Different Sections of the Small Intestine of Chickens Based on Exposure Duration

In this study, we examined the protein and gene expression of heat shock proteins (HSPs) in different sections of the small intestine of chickens. In total, 300 one-day-old Ross 308 broiler chicks were randomly allocated to the control and treatment groups. The treatment group was divided into four subgroups, according to the duration of acute heat exposure (3, 6, 12, and 24 h). The influence of heat stress on the protein and gene expression of HSP70, HSP60, and HSP47 in different sections of the small intestine of chickens was determined. The protein expression of HSP70 and HSP60 was significantly higher at 6 h in the duodenum and jejunum and 12 h in the ileum. The HSP47 protein expression was significantly higher at 3 h in the duodenum and ileum and at 6 h in the jejunum. The gene expression levels of HSP70, HSP60, and HSP47 were significantly higher at the 3 h treatment group than the control group in the duodenum, jejunum, and ileum. The glutamate pyruvate transaminase and glutamate oxaloacetate transaminase levels were significantly higher at 12 and 24 h in the serum of the blood. Acute heat stress affected the expression of intestinal proteins and genes in chickens, until the induction of heat tolerance.

Novel Chaperones RrGroEL and RrGroES for Activity and Stability Enhancement of Nitrilase in Escherichia coli and Rhodococcus ruber

For large-scale bioproduction, thermal stability is a crucial property for most industrial enzymes. A new method to improve both the thermal stability and activity of enzymes is of great significance. In this work, the novel chaperones RrGroEL and RrGroES from Rhodococcus ruber, a nontypical actinomycete with high organic solvent tolerance, were evaluated and applied for thermal stability and activity enhancement of a model enzyme, nitrilase. Two expression strategies, namely, fusion expression and co-expression, were compared in two different hosts, E. coli and R. ruber. In the E. coli host, fusion expression of nitrilase with either RrGroES or RrGroEL significantly enhanced nitrilase thermal stability (4.8-fold and 10.6-fold, respectively) but at the expense of enzyme activity (32-47% reduction). The co-expression strategy was applied in R. ruber via either a plasmid-only or genome-plus-plasmid method. Through integration of the nitrilase gene into the R. ruber genome at the site of nitrile hydratase (NHase) gene via CRISPR/Cas9 technology and overexpression of RrGroES or RrGroEL with a plasmid, the engineered strains R. ruber TH3 dNHase::RrNit (pNV18.1-Pami-RrNit-Pami-RrGroES) and TH3 dNHase::RrNit (pNV18.1-Pami-RrNit-Pami-RrGroEL) were constructed and showed remarkably enhanced nitrilase activity and thermal stability. In particular, the RrGroEL and nitrilase co-expressing mutant showed the best performance, with nitrilase activity and thermal stability 1.3- and 8.4-fold greater than that of the control TH3 (pNV18.1-Pami-RrNit), respectively. These findings are of great value for production of diverse chemicals using free bacterial cells as biocatalysts.

Stability of the chaperonin system GroEL-GroES under extreme environmental conditions

The chaperonin system GroEL-GroES is present in all kingdoms of life and rescues proteins from improper folding and aggregation upon internal and external stress conditions, including high temperatures and pressures. Here, we set out to explore the thermo- and piezostability of GroEL, GroES and the GroEL-GroES complex in the presence of cosolvents, nucleotides and salts employing quantitative FTIR spectroscopy and small-angle X-ray scattering. Owing to its high biological relevance and lack of data, our focus was especially on the effect of pressure on the chaperonin system. The experimental results reveal that the GroEL-GroES complex is remarkably temperature stable with an unfolding temperature beyond 70 °C, which can still be slightly increased by compatible cosolutes like TMAO. Conversely, the pressure stability of GroEL and hence the GroEL-GroES complex is rather limited and much less than that of monomeric proteins. Whereas GroES is pressure stable up to ∼5 kbar, GroEl and the GroEl-GroES complex undergo minor structural changes already beyond 1 kbar, which can be attributed to a dissociation-induced conformational drift. Quite unexpectedly, no significant unfolding of GroEL is observed even up to 10 kbar, however, i.e., the subunits themselves are very pressure stable. As for the physiological relevance, the structural integrity of the chaperonin system is retained in a relatively narrow pressure range, from about 1 to 1000 bar, which is just the pressure range encountered by life on Earth.

Differentiating between the effects of heat stress and lipopolysaccharide on the porcine ovarian heat shock protein response1

Heat stress (HS) negatively affects both human and farm-animal health and undermines efficiency in a variety of economically important agricultural variables, including reproduction. HS impairs the intestinal barrier, allowing for translocation of the resident microflora and endotoxins, such as lipopolysaccharide (LPS), from the gastrointestinal lumen into systemic circulation. While much is known about the cellular function of heat shock proteins (HSPs) in most tissues, the in vivo ovarian HSP response to stressful stimuli remains ill-defined. The purpose of this study was to compare the effects of HS or LPS on ovarian HSP expression in pigs. We hypothesized that ovarian HSPs are responsive to both HS and LPS. Altrenogest (15 mg/d) was administered per os for estrus synchronization (14 d) prior to treatment and three animal paradigms were used: (i) gilts were exposed to cyclical HS (31 ± 1.4 °C) or thermoneutral (TN; 20 ± 0.5 °C) conditions immediately following altrenogest withdrawal for 5 d during follicular development; (ii) gilts were subjected to repeated (4×/d) saline (CON) or LPS (0.1 μg/kg BW) i.v. infusion immediately following altrenogest withdrawal for 5 d; and (iii) gilts were subjected to TN (20 ± 1 °C) or cyclical HS (31 to 35 °C) conditions 2 d post estrus (dpe) until 12 dpe during the luteal phase. While no differences were detected for transcript abundances of the assessed ovarian HSP, the protein abundance of specific HSP was influenced by stressors during the follicular and luteal phases. HS during the follicular phase tended (P < 0.1) to increase ovarian protein abundance of HSP90AA1 and HSPA1A, and increased (P ≤ 0.05) HSF1, HSPD1, and HSPB1 compared with TN controls, while HS decreased HSP90AB1 (P = 0.01). Exposure to LPS increased (P < 0.05) HSP90AA1 and HSPA1A and tended (P < 0.1) to increase HSF1 and HSPB1 compared with CON gilts, while HSP90AB1 and HSPD1 were not affected by LPS. HS during the luteal phase increased (P < 0.05) abundance of HSPB1 in corpora lutea (CL), decreased (P < 0.05) CL HSP90AB1, but did not impact HSF1, HSPD1, HSP90AA1, or HSPA1A abundance. Thus, these data support that HS and LPS similarly regulate expression of specific ovarian HSP, which suggest that HS effects on the ovary are in part mediated by LPS.

Identification of watermelon heat shock protein members and tissue-specific gene expression analysis under combined drought and heat stresses

Heat shock protein (Hsp) gene family members in the watermelon genome were identified and characterized by bioinformatics analysis. In addition, expression profiles of genes under combined drought and heat stress conditions were experimentally analyzed. In the watermelon genome, 39 genes belonging to the sHsp family, 101 genes belonging to the Hsp40 family, 23 genes belonging to the Hsp60 family, 12 genes belonging to the Hsp70 family, 6 genes belonging to the Hsp90 family, and 102 genes belonging to the Hsp100 family were found. It was also observed that the proteins in the same cluster in the phylogenetic trees had similar motif patterns. When the estimated 3-dimensional structures of the Hsp proteins were examined, it was determined that the α-helical structure was dominant in almost all families. The most orthologous relationship appeared to be between watermelon, soybean, and poplar in the ClaHsp gene families. For tissue-specific gene expression analysis under combined stress conditions, expression analysis of one representative Hsp gene each from root, stem, leaf, and shoot tissues was performed by real-time PCR. A significant increase was detected usually at 30 min in almost all tissues. This study provides extensive information for watermelon Hsps, and can enhance our knowledge about the relationships between Hsp genes and combined stresses.

Oil-in-water Pickering emulsions using a protein nano-ring as high-grade emulsifiers

Pickering emulsion-based delivery of liposoluble bioactive ingredients employing protein nanoparticles as biocompatible emulsifiers is a promising choice for food, cosmetic, and medical industries. This paper reports a novel design of a protein nano-ring (termed SR') derived from chaperonin GroEL as an emulsifying agent, which has a naturally evolved hydrophobic binding rim in addition to its well-defined shape. It is shown that SR' adsorbed at rosemary oil/water interface and formed stable oil-in-water Pickering emulsions, with dispersed droplet size being dependent on the SR' concentration and oil/water ratio as well. The optimal formulation yielding stable nano-emulsions was determined to be at a SR' concentration between 0.30 wt.% and 0.45 wt.%, and an oil/water ratio of 0.05-0.20 (v/v). Meanwhile, we demonstrate that nano-sized Pickering droplets could be easily prepared irrespective of the examined external factors including pH, temperature and ionic strength, with the lowest droplet sizes being produced at pH = 7.0, temperature ≤ 40 °C, and ionic strength (NaCl concentration) ≤ 50 mM. Besides, rheological analysis revealed the gelation propensity of SR'-stabilized emulsions with high oil/water ratios, an advantageous property that would further enhance the emulsion stability. Finally, it is shown that the SR' emulsified system is able to protect β-carotene, which was used as a model of bioactive but labile compound. This work, in the context of the current drive for biocompatibility and sustainability, is believed to provide opportunities for emulsion-based applications to switch towards greener solutions.

Age-related responses to a bout of mechanotherapy in skeletal muscle of rats

Cyclic compressive loading (CCL) is a massage mimetic that improves muscle regrowth from atrophy in adult rats. Therefore, we tested if a single bout of CCL increases anabolic signaling and protein synthesis in muscle during normal, weight-bearing conditions in gastrocnemius muscle from adult and aged rats. Male Brown Norway/F344 rats at 10 (adult) and 30 (aged) months of age were assigned control or CCL (receiving a single bout of CCL). Twenty-four hours following a single bout of CCL there was no change in protein synthesis, Akt, or GSK3β signaling at either age, despite adult rats having higher abundance and activation of mechanosensitive pathways (integrins and integrin-linked kinase). Murf1 was elevated in response to CCL in both age groups, potentially indicating muscle remodeling. Muscle from aged rats exhibited an increase in heat shock protein (HSP) 25 and HSP70 and in the cold shock protein RNA-binding motif 3 (RBM3), demonstrating a unique stress response to CCL in aged muscle only. Finally, muscle from aged rats exhibited higher basal protein synthesis that was corroborated by elevated eIF2Bε and rpS6 signaling, without an additional effect of CCL. In summary, a single bout of CCL does not have anabolic effects on skeletal muscle during normal, weight-bearing conditions, even though it has previously been shown to improve regrowth from atrophy. These data demonstrate that interventions that may help recover from atrophy do not necessarily induce muscle hypertrophy in unperturbed conditions.NEW & NOTEWORTHY Massage has been demonstrated to be an effective mechanotherapy to improve recovery from atrophy in adult skeletal muscle; however, this study shows that a single bout of massage fails to increase protein synthesis or anabolic signaling in adult or aged skeletal muscle during normal, weight-bearing conditions. Altogether, our data suggest massage is a useful mechanotherapy for preserving skeletal muscle when combined with other interventions but is not an anabolic stimulus on its own.

Osmolytes ameliorate the effects of stress in the absence of the heat shock protein Hsp104 in Saccharomyces cerevisiae

Aggregation of the prion protein has strong implications in the human prion disease. Sup35p is a yeast prion, and has been used as a model protein to study the disease mechanism. We have studied the pattern of Sup35p aggregation inside live yeast cells under stress, by using confocal microscopy, fluorescence activated cell sorting and western blotting. Heat shock proteins are a family of proteins that are produced by yeast cells in response to exposure to stressful conditions. Many of the proteins behave as chaperones to combat stress-induced protein misfolding and aggregation. In spite of this, yeast also produce small molecules called osmolytes during stress. In our work, we tried to find the reason as to why yeast produce osmolytes and showed that the osmolytes are paramount to ameliorate the long-term effects of lethal stress in Saccharomyces cerevisiae, either in the presence or absence of Hsp104p.

Identifying S-nitrosylated proteins and unraveling S-nitrosoglutathione reductase-modulated sodic alkaline stress tolerance in Solanum lycopersicum L

S-nitrosylation, regulated by S-nitrosoglutathione reductase (GSNOR), is considered as an important route for nitric oxide (NO)-modulated stress tolerance in plants. However, genetic evidence for the GSNOR-mediated integrated regulation of S-nitrosylation and plant stress response remains elusive until now. In the present study, we used a site-specific nitrosoproteomic approach to identify 334 endogenously S-nitrosylated proteins with 425 S-nitrosylated sites from the wild type (WT) and GSNOR-knockdown (G) tomato plants under both control (C) and sodic alkaline stress (S) conditions. In detail, the results revealed 68, 92, 54 and 56 up-regulated, as well as 10, 36, 14 and 10 down-regulated S-nitrosylated proteins in G-C/WT-C, G-S/WT-S, WT-S/WT-C, and G-S/G-C, which is the first dataset for S-nitrosylated proteins in Solanaceae. These S-nitrosylated proteins are involved in a wide range of various metabolic, cellular and catalytic processes. Based on this data, proteins involving in NO homeostasis control, signaling of Ca²⁺, ethylene and MAPK, reactive oxygen species (ROS) scavenging, osmotic regulation, as well as energy support pathway have been identified and selected as the key and sensitive targets that were regulated by GSNOR-modulated S-nitrosylation in response to sodic alkaline stress. Taken together, GSNOR is actively involved in the regulation of sodic alkaline stress tolerance by S-nitrosylation. And the present study provided valuable resources and new clues for the study of S-nitrosylation-regulated metabolism in tomato plants.

Role of heat shock proteins 70/90 in exercise physiology and exercise immunology and their diagnostic potential in sports

Heat shock proteins (HSPs) are molecular chaperones facilitating the unfolding or folding of secondary structures of proteins, their client proteins, in cellular stress situations. Various internal and external physiological and mechanical stress factors induce a homeostatic imbalance, followed by an increased expression of HSP70 and HSP90. Exercise is a stress factor, too, and its cumulative physiological perturbation manifests at a cellular level by threatening the protein homeostasis of various cell types. Consequently, an increase of HSP70/90 was described in plasma and mononuclear cells and various organs and tissues, such as muscle, liver, cardiac tissue, and brain, after an acute bout of exercise. The specific response of HSP70/90 seems to be strongly related to the modality of exercise, with several dependent factors such as duration, intensity, exercise type, subjects’ training status, and environmental factors, e.g., temperature. It is suggested that HSP70/90 play a major role in immune regulation and cell protection during exercise and in the efficiency of regeneration and reparation processes. During long-term training, HSP70/90 are involved in preconditioning and adaptation processes that might also be important for disease prevention and therapy. With regard to their highly sensitive and individual response to specific exercise and training modalities, this review discusses whether and how HSP70 and HSP90 can be applied as biomarkers for monitoring exercise and training.

A Review of the Potential Effect of Electroacupuncture and Moxibustion on Cell Repair and Survival: The Role of Heat Shock Proteins

In recent years, a considerable amount of research has been focused on the underlying mechanisms of electroacupuncture and moxibustion assisted tissue repair. Intracellular protein denaturation is a significant pathological step of acute conditions such as stroke, myocardial infarction and acute pancreatitis. Protein aggregation can be observed after the protein denaturation step in chronic diseases of the central nervous system like Alzheimer's and Parkinson's disease, and also in other chronic system diseases including cataract formation. Heat shock proteins (HSPs) are fundamental for intracellular protein repair and work by preventing protein aggregation and assisting denaturated proteins to refold. Further, HSPs can also function for extracellular cell signalling. The focus of this review is to analyse the data studying electroacupuncture and moxibustion induced HSPs, and how acupuncture can survive cells from apoptosis under stress.

Atomic-Level Description of Protein Folding inside the GroEL Cavity

Chaperonins (ubiquitous facilitators of protein folding) sequester misfolded proteins within an internal cavity, thus preventing protein aggregation during the process of refolding. GroEL, a tetradecameric bacterial chaperonin, is one of the most studied chaperonins, but the role of the internal cavity in the refolding process is still unclear. It has been suggested that rather than simply isolating proteins while they refold, the GroEL cavity actively promotes protein folding. A detailed characterization of the folding dynamics and thermodynamics of protein substrates encapsulated within the cavity, however, has been difficult to obtain by experimental means, due to the system's complexity and the many steps in the folding cycle. Here, we examine the influence of the GroEL cavity on protein folding based on the results of unbiased, atomistic molecular dynamics simulations. We first verified that the computational setup, which uses a recently developed state-of-the-art force field that more accurately reproduces the aggregation propensity of unfolded states, could recapitulate the essential structural dynamics of GroEL. In these simulations, the GroEL tetradecamer was highly dynamic, transitioning among states corresponding to most of the structures that have been observed experimentally. We then simulated a small, unfolded protein both in the GroEL cavity and in bulk solution and compared the protein's folding process within these two environments. Inside the GroEL cavity, the unfolded protein interacted strongly with the disordered residues in GroEL's C-terminal tails. These interactions stabilized the protein's unfolded states relative to its compact states and increased the roughness of its folding free-energy surface, resulting in slower folding compared to the rate in solution. For larger proteins, which are more typical GroEL substrates, we speculate that these interactions may allow substrates to more quickly escape kinetic traps associated with compact, misfolded states, thereby actively promoting folding.

Rpn11-mediated ubiquitin processing in an ancestral archaeal ubiquitination system

While protein ubiquitination was long believed to be a truly eukaryotic feature, recently sequenced genomes revealed complete ubiquitin (Ub) modification operons in archaea. Here, we present the structural and mechanistic characterization of an archaeal Rpn11 deubiquitinase from Caldiarchaeum subterraneum, CsRpn11, and its role in the processing of CsUb precursor and ubiquitinated proteins. CsRpn11 activity is affected by the catalytic metal ion type, small molecule inhibitors, sequence characteristics at the cleavage site, and the folding state of CsUb-conjugated proteins. Comparison of CsRpn11 and CsRpn11-CsUb crystal structures reveals a crucial conformational switch in the CsRpn11 Ins-1 site, which positions CsUb for catalysis. The presence of this transition in a primordial soluble Rpn11 thus predates the evolution of eukaryotic Rpn11 immobilized in the proteasomal lid. Complementing phylogenetic studies, which designate CsRpn11 and CsUb as close homologs of the respective eukaryotic proteins, our results provide experimental support for an archaeal origin of protein ubiquitination.

The Chaperonin GroEL: A Versatile Tool for Applied Biotechnology Platforms

The nucleotide-free chaperonin GroEL is capable of capturing transient unfolded or partially unfolded states that flicker in and out of existence due to large-scale protein dynamic vibrational modes. In this work, three short vignettes are presented to highlight our continuing advances in the application of GroEL biosensor biolayer interferometry (BLI) technologies and includes expanded uses of GroEL as a molecular scaffold for electron microscopy determination. The first example presents an extension of the ability to detect dynamic pre-aggregate transients in therapeutic protein solutions where the assessment of the kinetic stability of any folded protein or, as shown herein, quantitative detection of mutant-type protein when mixed with wild-type native counterparts. Secondly, using a BLI denaturation pulse assay with GroEL, the comparison of kinetically controlled denaturation isotherms of various von Willebrand factor (vWF) triple A domain mutant-types is shown. These mutant-types are single point mutations that locally disorder the A1 platelet binding domain resulting in one gain of function and one loss of function phenotype. Clear, separate, and reproducible kinetic deviations in the mutant-type isotherms exist when compared with the wild-type curve. Finally, expanding on previous electron microscopy (EM) advances using GroEL as both a protein scaffold surface and a release platform, examples are presented where GroEL-protein complexes can be imaged using electron microscopy tilt series and the low-resolution structures of aggregation-prone proteins that have interacted with GroEL. The ability of GroEL to bind hydrophobic regions and transient partially folded states allows one to employ this unique molecular chaperone both as a versatile structural scaffold and as a sensor of a protein's folded states.

The transcriptomic and proteomic responses of Daphnia pulex to changes in temperature and food supply comprise environment-specific and clone-specific elements

Background

Regulatory adjustments to acute and chronic temperature changes are highly important for aquatic ectotherms because temperature affects their metabolic rate as well as the already low oxygen concentration in water, which can upset their energy balance. This also applies to severe changes in food supply. Thus, we studied on a molecular level (transcriptomics and/or proteomics) the immediate responses to heat stress and starvation and the acclimation to different temperatures in two clonal isolates of the model microcrustacean Daphnia pulex from more or less stressful environments, which showed a higher (clone M) or lower (clone G) tolerance to heat and starvation.

Results

The transcriptomic responses of clone G to acute heat stress (from 20 °C to 30 °C) and temperature acclimation (10 °C, 20 °C, and 24 °C) and the proteomic responses of both clones to acute heat, starvation, and heat-and-starvation stress comprised environment-specific and clone-specific elements. Acute stress (in particular heat stress) led to an early upregulation of stress genes and proteins (e.g., molecular chaperones) and a downregulation of metabolic genes and proteins (e.g., hydrolases). The transcriptomic responses to temperature acclimation differed clearly. They also varied depending on the temperature level. Acclimation to higher temperatures comprised an upregulation of metabolic genes and, in case of 24 °C acclimation, a downregulation of genes for translational processes and collagens. The proteomic responses of the clones M and G differed at any type of stress. Clone M showed markedly stronger and less stress-specific proteomic responses than clone G, which included the consistent expression of a specific heat shock protein (HSP60) and vitellogenin (VTG-SOD).

Conclusions

The expression changes under acute stress can be interpreted as a switch from standard products of gene expression to stress-specific products. The expression changes under temperature acclimation probably served for an increase in energy intake (via digestion) and, if necessary, a decrease in energy expenditures (e.g, for translational processes). The stronger and less stress-specific proteomic responses of clone M indicate a lower degree of cell damage and an active preservation of the energy balance, which allowed adequate proteomic responses under stress, including the initiation of resting egg production (VTG-SOD expression) as an emergency reaction.

Electronic supplementary material

The online version of this article (10.1186/s12864-018-4742-6) contains supplementary material, which is available to authorized users.

HSP60 and HSP90β from blunt snout bream, Megalobrama amblycephala: Molecular cloning, characterization, and comparative response to intermittent thermal stress and Aeromonas hydrophila infection

Heat shock proteins (HSPs) play critical roles in the process of anti-stress and immunity and are implicated in autoimmune diseases. In order to understand the comparative stress responses of HSP60 and HSP90β under intermittent thermal stress and Aeromonas hydrophila infection, we cloned their full-length cDNAs from Megalobrama amblycephala liver, predicted their secondary and tertiary structure, and examined their tissue-specific expression patterns. The full length of HSP60 and HSP90β cDNAs indicated that they included all signature sequences of corresponding protein families. They showed high homology to their counterparts in other species, and were consistent with the known classification of fishes based on phylogenetic analysis. HSP60 showed the highest expression in head-kidney, brain, and gill, while HSP90β presented higher in hindgut, liver, and brain. Significant mRNA expression differences were determined between HSP60 and HSP90β in tissues of bladder, liver, heart, and gill. During thermal stress and recovery phase, the highest expression of them were observed at the first recovery for 2 d and 1 d, respectively. The expression between them were extremely significant difference during the first recovery and second stress period. After A. hydrophila infection, their expressions were extremely significantly upregulated. The significant upregulation and rapid response indicated that they were sensitive to thermal stress and bacterial challenge. This study demonstrated that HSP60 and HSP90β might participate in innate immune and environmental responses of M. amblycephala. It indicated that they could be used as biomarkers to test the stress caused by local aquaculture environment.

Multi-omics Reveal Specific Targets of the RNA-Binding Protein Puf3p and Its Orchestration of Mitochondrial Biogenesis

Coenzyme Q (CoQ) is a redox-active lipid required for mitochondrial oxidative phosphorylation (OxPhos). How CoQ biosynthesis is coordinated with the biogenesis of OxPhos protein complexes is unclear. Here, we show that the Saccharomyces cerevisiae RNA-binding protein (RBP) Puf3p regulates CoQ biosynthesis. To establish the mechanism for this regulation, we employed a multi-omic strategy to identify mRNAs that not only bind Puf3p but also are regulated by Puf3p in vivo. The CoQ biosynthesis enzyme Coq5p is a critical Puf3p target: Puf3p regulates the abundance of Coq5p and prevents its detrimental hyperaccumulation, thereby enabling efficient CoQ production. More broadly, Puf3p represses a specific set of proteins involved in mitochondrial protein import, translation, and OxPhos complex assembly (pathways essential to prime mitochondrial biogenesis). Our data reveal a mechanism for post-transcriptionally coordinating CoQ production with OxPhos biogenesis, and they demonstrate the power of multi-omics for defining genuine targets of RBPs.

Chaperonin-Nanocaged Hemin as an Artificial Metalloenzyme for Oxidation Catalysis

Taking inspiration from biology's effectiveness in functionalizing protein-based nanocages for chemical processes, we describe here a rational design of an artificial metalloenzyme for oxidations with the bacterial chaperonin GroEL, a nanocage for protein folding in nature, by supramolecular anchoring of catalytically active hemin in its hydrophobic central cavity. The promiscuity of the chaperonin cavity is an essential element of this design, which can mimic the hydrophobic binding pocket in natural metalloenzymes to accept cofactor and substrate without requiring specific ligand-protein interactions. The success of this approach is manifested in the efficient loading of multiple monomeric hemin cofactors to the GroEL cavity by detergent dialysis and good catalytic oxidation properties of the resulting biohybrid in tandem with those of the clean oxidant of H₂O₂. Investigation of the mechanism of hemin-GroEL-catalyzed oxidation of two-model substrates reveals that the kinetic behavior of the complex follows a ping-pong mechanism in both cases. Through comparison with horseradish peroxidase, the oxidative activity and stability of hemin-GroEL were observed to be similar to those found in natural peroxidases. Adenosine 5'-triphosphate (ATP)-regulated partial dissociation of the biohybrid, as assessed by the reduction of its catalytic activity with the addition of the nucleotide, raises the prospect that ATP may be used to recycle the chaperonin scaffold. Moreover, hemin-GroEL can be applied to the chromogenic detection of H₂O₂, which (or peroxide in general) is commonly contained in industrial wastes. Considering the rich chemistry of free metalloporphyrins and the ease of production of GroEL and its supramolecular complex with hemin, this work should seed the creation of many new artificial metalloenzymes with diverse reactivities.

Cloning and characterization of thermostable GroEL/GroES homologues from Geobacillus thermopakistaniensis and their applications in protein folding

The chaperonin genes encoding GroEL_Gt (ESU72018) and GroES_Gt (ESU72017), homologues of bacterial GroEL and GroES, from Geobacillus thermopakistaniensis were cloned and expressed in Escherichia coli. The purified gene products possessed the ATPase activity similar to other bacterial and eukaryal counterparts. Recombinant GroEL_Gt and GroES_Gt were able to refold the denatured insoluble aggregates of α-amylase from Bacillus licheniformis into soluble and active form. Furthermore, GroEL_Gt and GroES_Gt successfully enhanced the thermostability of porcine heart malate dehydrogenase. Expression of GroEL_Gt gene in E. coli cells enhanced the thermotolerance of the host. Furthermore, soluble production of recombinant alcohol dehydrogenase from Bacillus subtilis strain R5 in E. coli, initially produced as insoluble aggregates, was achieved by co-expressing the gene with GroEL_Gt. Our results implied that GroEL_Gt could assist folding of nascent protein in E. coli with the help of host co-chaperonin without requiring additional ATP. This system can be used for soluble production of recombinant proteins which otherwise are produced in insoluble form in E. coli. To the best of our knowledge this is the first report on functional characterization and applications of chaperonins from genus Geobacillus.

Mitochondrial Chaperonin HSP60 Is the Apoptosis-Related Target for Myrtucommulone

The acylphloroglucinol myrtucommulone A (MC) causes mitochondrial dysfunctions by direct interference leading to apoptosis in cancer cells, but the molecular targets involved are unknown. Here, we reveal the chaperonin heat-shock protein 60 (HSP60) as a molecular target of MC that seemingly modulates HSP60-mediated mitochondrial functions. Exploiting an unbiased, discriminative protein fishing approach using MC as bait and mitochondrial lysates from leukemic HL-60 cells as target source identified HSP60 as an MC-binding protein. MC prevented HSP60-mediated reactivation of denatured malate dehydrogenase in a protein refolding assay. Interference of MC with HSP60 was accompanied by aggregation of two proteins in isolated mitochondria under heat shock that were identified as Lon protease-like protein (LONP) and leucine-rich PPR motif-containing protein (LRP130). Together, our results reveal HSP60 as a direct target of MC, proposing MC as a valuable tool for studying HSP60 biology and for evaluating its value as a target in related diseases, such as cancer.

Bacterial community dynamics are linked to patterns of coral heat tolerance

Ocean warming threatens corals and the coral reef ecosystem. Nevertheless, corals can be adapted to their thermal environment and inherit heat tolerance across generations. In addition, the diverse microbes that associate with corals have the capacity for more rapid change, potentially aiding the adaptation of long-lived corals. Here, we show that the microbiome of reef corals is different across thermally variable habitats and changes over time when corals are reciprocally transplanted. Exposing these corals to thermal bleaching conditions changes the microbiome for heat-sensitive corals, but not for heat-tolerant corals growing in habitats with natural high heat extremes. Importantly, particular bacterial taxa predict the coral host response in a short-term heat stress experiment. Such associations could result from parallel responses of the coral and the microbial community to living at high natural temperatures. A competing hypothesis is that the microbial community and coral heat tolerance are causally linked.

Coral-associated microbes could enhance the capacity of their host organism to respond to environmental change. Ziegler and colleagues use a reciprocal transplant experiment to show that microbiomes of heat-tolerant corals are more resilient to change than those of heat-sensitive corals.

Differences in structure and changes in gene regulation of murrel molecular chaperone HSP family during epizootic ulcerative syndrome (EUS) infection

Heat shock proteins (HSPs) are immunogenic, ubiquitous class of molecular chaperones, which are induced in response to various environmental and microbial stressful conditions. It plays a vital role in maintaining cellular protein homeostasis in eukaryotic cells. In this study, we described a comprehensive comparative data by bioinformatics approach on three different full length cDNA sequences of HSP family at molecular level. The cDNA sequences of three HSPs were identified from constructed cDNA library of Channa striatus and named as CsCPN60, CsHSP60 and CsHSP70. We have conducted various physicochemical study, which showed that CsHSP70 (666 amino acid) possessed a larger polypeptides followed by CsCPN60 (575) and CsCPN60 (542). Three dimensional structural analysis of these HSPs showed maximum residues in α-helices and least in β-sheets; also CsHSP60 lacks β-sheet and formed helix-turn-helix structure. Further analysis indicated that each HSP carried distinct domains and gene specific signature motif, which showed that each HSP are structurally diverse. Homology and phylogenetic study showed that the sequences taken for analysis shared maximum identity with fish HSP family. Tissue specific mRNA expression analysis revealed that all the HSPs showed maximum expression in one of the major immune organ such as CsCPN60 in kidney, CsHSP60 in spleen and CsHSP70 in head kidney. To understand the function of HSPs in murrel immune system, the elevation in mRNA expression level was analyzed against microbial oxidative stressors such as fungal (Aphanomyces invadans) and bacterial (Aeromonas hydrophila). It is interesting to note that all the HSP showed a different expression pattern and reached maximum up-regulation at 48 h post-infection (p.i) during fungal stress, whereas in bacterial stress only CsCPN60 showed maximum up-regulation at 48 h p.i, but CsHSP60 and CsHSP70 showed maximum up-regulation at 24 h p.i. The differential expression pattern showed that each HSP is diverse in function. Overall, the elevation in expression levels showed that HSPs might have potential involvement in murrel immune protection thus, protecting the organism against various external stimuli including environmental and microbial stress.

Characterization and function analysis of Hsp60 and Hsp10 under different acute stresses in black tiger shrimp, Penaeus monodon

Heat shock proteins (Hsps) are a class of highly conserved proteins produced in virtually all living organisms from bacteria to humans. Hsp60 and Hsp10, the most important mitochondrial chaperones, participate in environmental stress responses. In this study, the full-length complementary DNAs (cDNAs) of Hsp60 (PmHsp60) and Hsp10 (PmHsp10) were cloned from Penaeus monodon. Sequence analysis showed that PmHsp60 and PmHsp10 encoded polypeptides of 578 and 102 amino acids, respectively. The expression profiles of PmHsp60 and PmHsp10 were detected in the gills and hepatopancreas of the shrimps under pH challenge, osmotic stress, and heavy metal exposure, and results suggested that PmHsp60 and PmHsp10 were involved in the responses to these stimuli. ATPase and chaperone activity assay indicated that PmHsp60 could slow down protein denaturation and that Hsp60/Hsp10 may be combined to produce a chaperone complex with effective chaperone and ATPase activities. Overall, this study provides useful information to help further understand the functional mechanisms of the environmental stress responses of Hsp60 and Hsp10 in shrimp.

Screening and Identification of Antigenic Proteins from the Hard Tick Dermacentor silvarum (Acari: Ixodidae)

In order to explore tick proteins as potential targets for further developing vaccine against ticks, the total proteins of unfed female Dermacentor silvarum were screened with anti-D. silvarum serum produced from rabbits. The results of western blot showed that 3 antigenic proteins of about 100, 68, and 52 kDa were detected by polyclonal antibodies, which means that they probably have immunogenicity. Then, unfed female tick proteins were separated by 12% SDS-PAGE, and target proteins (100, 68, and 52 kDa) were cut and analyzed by LC-MS/MS, respectively. The comparative results of peptide sequences showed that they might be vitellogenin (Vg), heat shock protein 60 (Hsp60), and fructose-1, 6-bisphosphate aldolase (FBA), respectively. These data will lay the foundation for the further validation of antigenic proteins to prevent infestation and diseases transmitted by D. silvarum.

Expression profiles of heat shock protein 27 and αB-crystallin and their effects on heat-stressed rat myocardial cells in vitro and in vivo

The present study established a heat-stressed rat heart model, and used an H9c2 myocardial cell line to investigate the expression profiles of heat shock protein (Hsp)27 and αB-crystallin, both in vivo and in vitro. Rats and myocardial cells were subjected to 42 ˚C for 0, 20, 40, 60, 80 or 100 min, following which the mRNA and protein expression levels of Hsp27 and αB-crystallin were measured. Following heat shock, the protein expression levels of Hsp27 and αB-crystallin were significantly decreased in the rat heart cells in vivo, whereas their mRNA levels were significantly increased. The opposing association between the protein and mRNA expression levels of Hsp27 and αB-crystallin suggests that the progression from mRNA into proteins via translation may delayed, or proteins may exist as either oligomers or in the phosphorylated form under heat stress. In vitro, Hsp27 and αB-crystallin exhibited similar reductions in the protein levels at 40 and 60 min, then increased to normal values following 80 min of heat stress. However, the mRNA levels were not consistent with the protein levels. The mRNA levels of Hsp27 and αB-crystallin did however exhibit similar tendencies following 60 min of heat stress. The present study investigated these apparently conflicting results between the in vitro cell line and the in vivo body system. The results demonstrated that the protein and mRNA expression levels of Hsp27 and αB-crystallin exhibited similar trends in vivo and in vitro, respectively. These results were confirmed by analysis with STRING 9.1 software, which indicated that Hsp27 and αB-crystallin are co-expressed in rat myocardial cells. However, the individual cell lines and whole body system exhibited different trends in Hsp27 and αB-crystallin levels prior to and following heat stress, thus require further investigation.

Mitochondrial Dynamics and Heart Failure

Mitochondrial dynamics, fission and fusion, were first identified in yeast with investigation in heart cells beginning only in the last 5 to 7 years. In the ensuing time, it has become evident that these processes are not only required for healthy mitochondria, but also, that derangement of these processes contributes to disease. The fission and fusion proteins have a number of functions beyond the mitochondrial dynamics. Many of these functions are related to their membrane activities, such as apoptosis. However, other functions involve other areas of the mitochondria, such as OPA1's role in maintaining cristae structure and preventing cytochrome c leak, and its essential (at least a 10 kDa fragment of OPA1) role in mtDNA replication. In heart disease, changes in expression of these important proteins can have detrimental effects on mitochondrial and cellular function.

Characterization of Precursor PfHsp60 in Plasmodium falciparum Cytosol during Its Asexual Development in Human Erythrocytes

Mitochondrial heat shock protein 60 (Hsp60) is a nuclear encoded gene product that gets post-translationally translocated into the mitochondria. Using multiple approaches such as immunofluorescence experiments, isoelectric point analysis with two-dimensional gel electrophoresis, and mass spectrometric identification of the signal peptide, we show that Hsp60 from Plasmodium falciparum (PfHsp60) accumulates in the parasite cytoplasm during the ring, trophozoite, and schizont stages of parasite development before being imported into the parasite mitochondria. Using co-immunoprecipitation experiments with antibodies specific to cytoplasmic PfHsp90, PfHsp70-1, and PfHsp60, we show association of precursor PfHsp60 with cytoplasmic chaperone machinery. Metabolic labeling involving pulse and chase indicates translocation of the precursor pool into the parasite mitochondrion during chase. Analysis of results obtained with Geldanamycin treatment confirmed precursor PfHsp60 to be one of the clients for PfHsp90. Cytosolic chaperones bind precursor PfHsp60 prior to its import into the mitochondrion of the parasite. Our data suggests an inefficient co-ordination in the synthesis and translocation of mitochondrial PfHsp60 during asexual growth of malaria parasite in human erythrocytes.

Degradation of benzotrifluoride via the dioxygenase pathway in Rhodococcus sp. 065240

We previously isolated Rhodococcus sp. 065240, which catalyzes the defluorination of benzotrifluoride (BTF). In order to investigate the mechanism of this degradation of BTF, we performed proteomic analysis of cells grown with or without BTF. Three proteins, which resemble dioxygenase pathway enzymes responsible for isopropylbenzene degradation from Rhodococcus erythropolis BD2, were induced by BTF. Genomic PCR and DNA sequence analysis revealed that the Rhodococcus sp. 065240 carries the gene cluster, btf, which is highly homologous to the ipb gene cluster from R. erythropolis BD2. A mutant strain, which could not catalyze BTF defluorination, was isolated from 065240 strain by UV mutagenesis. The mutant strain had one mutation in the btfT gene, which encodes a response regulator of the two component system. The defluorinating ability of the mutant strain was recovered by complementation of btfT. These results suggest that the btf gene cluster is responsible for degradation of BTF.

Probing the kinetic stabilities of Friedreich's ataxia clinical variants using a solid phase GroEL chaperonin capture platform

Numerous human diseases are caused by protein folding defects where the protein may become more susceptible to degradation or aggregation. Aberrant protein folding can affect the kinetic stability of the proteins even if these proteins appear to be soluble in vivo. Experimental discrimination between functional properly folded and misfolded nonfunctional conformers is not always straightforward at near physiological conditions. The differences in the kinetic behavior of two initially folded frataxin clinical variants were examined using a high affinity chaperonin kinetic trap approach at 25 °C. The kinetically stable wild type frataxin (FXN) shows no visible partitioning onto the chaperonin. In contrast, the clinical variants FXN-p.Asp122Tyr and FXN-p.Ile154Phe kinetically populate partial folded forms that tightly bind the GroEL chaperonin platform. The initially soluble FXN-p.Ile154Phe variant partitions onto GroEL more rapidly and is more kinetically liable. These differences in kinetic stability were confirmed using differential scanning fluorimetry. The kinetic and aggregation stability differences of these variants may lead to the distinct functional impairments described in Friedreich's ataxia, the neurodegenerative disease associated to frataxin functional deficiency. This chaperonin platform approach may be useful for identifying small molecule stabilizers since stabilizing ligands to frataxin variants should lead to a concomitant decrease in chaperonin binding.

Probing structurally altered and aggregated states of therapeutically relevant proteins using GroEL coupled to bio-layer interferometry

The ability of a GroEL-based bio-layer interferometry (BLI) assay to detect structurally altered and/or aggregated species of pharmaceutically relevant proteins is demonstrated. Assay development included optimizing biotinylated-GroEL immobilization to streptavidin biosensors, combined with biophysical and activity measurements showing native and biotinylated GroEL are both stable and active. First, acidic fibroblast growth factor (FGF-1) was incubated under conditions known to promote (40°C) and inhibit (heparin addition) molten globule formation. Heat exposed (40°C) FGF-1 exhibited binding to GroEL-biosensors, which was significantly diminished in the presence of heparin. Second, a polyclonal human IgG solution containing 6-8% non-native dimer showed an increase in higher molecular weight aggregates upon heating by size exclusion chromatography (SEC). The poly IgG solution displayed binding to GroEL-biosensors initially with progressively increased binding upon heating. Enriched preparations of the IgG dimers or monomers showed significant binding to GroEL-biosensors. Finally, a thermally treated IgG1 monoclonal antibody (mAb) solution also demonstrated increased GroEL-biosensor binding, but with different kinetics. The bound complexes could be partially to fully dissociated after ATP addition (i.e., specific GroEL binding) depending on the protein, environmental stress, and the assay's experimental conditions. Transmission electron microscopy (TEM) images of GroEL-mAb complexes, released from the biosensor, also confirmed interaction of bound complexes at the GroEL binding site with heat-stressed mAb. Results indicate that the GroEL-biosensor-BLI method can detect conformationally altered and/or early aggregation states of proteins, and may potentially be useful as a rapid, stability-indicating biosensor assay for monitoring the structural integrity and physical stability of therapeutic protein candidates.

Evidence of oxidative stress in young and aged DJ-1-deficient mice

Loss of DJ-1 function contributes to pathogenesis in Parkinson's disease. Here, we investigate the impact of aging and DJ-1 deficiency in transgenic mice. Ventral midbrain from young DJ-1-deficient mice revealed no change in 4-hydroxy-2-nonenal (4-HNE), but HSP60, HSP40 and striatal dopamine turnover were significantly elevated compared to wildtype. In aged mice, the chaperone response observed in wildtype animals was absent from DJ-1-deficient transgenics, and nigral 4-HNE immunoreactivity was enhanced. These changes were concomitant with increased striatal dopamine levels and uptake. Thus, increased oxidants and diminished protein quality control may contribute to nigral oxidative damage with aging in the model.

Identification of elements that dictate the specificity of mitochondrial Hsp60 for its co-chaperonin

Type I chaperonins (cpn60/Hsp60) are essential proteins that mediate the folding of proteins in bacteria, chloroplast and mitochondria. Despite the high sequence homology among chaperonins, the mitochondrial chaperonin system has developed unique properties that distinguish it from the widely-studied bacterial system (GroEL and GroES). The most relevant difference to this study is that mitochondrial chaperonins are able to refold denatured proteins only with the assistance of the mitochondrial co-chaperonin. This is in contrast to the bacterial chaperonin, which is able to function with the help of co-chaperonin from any source. The goal of our work was to determine structural elements that govern the specificity between chaperonin and co-chaperonin pairs using mitochondrial Hsp60 as model system. We used a mutagenesis approach to obtain human mitochondrial Hsp60 mutants that are able to function with the bacterial co-chaperonin, GroES. We isolated two mutants, a single mutant (E321K) and a double mutant (R264K/E358K) that, together with GroES, were able to rescue an E. coli strain, in which the endogenous chaperonin system was silenced. Although the mutations are located in the apical domain of the chaperonin, where the interaction with co-chaperonin takes place, none of the residues are located in positions that are directly responsible for co-chaperonin binding. Moreover, while both mutants were able to function with GroES, they showed distinct functional and structural properties. Our results indicate that the phenotype of the E321K mutant is caused mainly by a profound increase in the binding affinity to all co-chaperonins, while the phenotype of R264K/E358K is caused by a slight increase in affinity toward co-chaperonins that is accompanied by an alteration in the allosteric signal transmitted upon nucleotide binding. The latter changes lead to a great increase in affinity for GroES, with only a minor increase in affinity toward the mammalian mitochondrial co-chaperonin.