The Plasmodium falciparum heat shock protein 40, Pfj4, associates with heat shock protein 70 and shows similar heat induction and localisation patterns

Human cerebral malaria is caused by the protozoan parasite Plasmodium falciparum, which establishes itself within erythrocytes. The normal body temperature in the human host could constitute a possible source of heat stress to the parasite. Molecular chaperones belonging to the heat shock protein (Hsp) class are thought to be important for parasite subsistence in the host cell, as the expression of some members of this family has been reported to increase upon heat shock. In this paper we investigated the possible functions of the P. falciparum heat shock protein DnaJ homologue Pfj4, a type II Hsp40 protein. We analysed the ability of Pfj4 to functionally replace Escherichia coli Hsp40 proteins in a dnaJ cbpA mutant strain. Western analysis on cellular fractions of P. falciparum-infected erythrocytes revealed that Pfj4 expression increased upon heat shock. Localisation studies using immunofluorescence and immuno-electron microscopy suggested that Pfj4 and P. falciparum Hsp70, PfHsp70-1, were both localised to the parasites nucleus and cytoplasm. In some cases, Pfj4 was also detected in the erythrocyte cytoplasm of infected erythrocytes. Immunoprecipitation studies and size exclusion chromatography indicated that Pfj4 and PfHsp70-1 may directly or indirectly interact. Our results suggest a possible involvement of Pfj4 together with PfHsp70-1 in cytoprotection, and therefore, parasite survival inside the erythrocyte.     

Activity of plant extracts on the respiratory burst and the stress protein synthesis

Aqueous, methanol and dichloromethane extracts from Artemisia copa, Baccharis grisebachii, Baccharis incarum, Baccharis latifolia, Mutisia kurtzii and Pluchea sagittalis, plants used in the Traditional Medicine of South America, are studied for activity on the respiratory burst and the inducible heat shock protein of 72 kD (hsp72) synthesis. Activity on the production of reactive oxygen species (ROS) and reactive nitrogen species (RNS), as well as on hsp72 synthesis was measured by flow cytometry in human neutrophils. Cells were stimulated using hydrogen peroxide, phorbol-12-myristate-13-acetate (PMA) or formyl-methionyl-leucyl-phenylalanine (FMLP) for ROS generation, and sodium nitroprusside (SNP) or PMA in the presence of calmodulin inhibitor W-13 for RNS. The production of hsp72 was induced by heat, PMA, H2O2 and SNP. The best inhibitory activity was shown by the dichloromethane extracts of Baccharis grisebachii and Pluchea sagittalis that were active in all the assays. The aqueous extract of Pluchea sagittalis was also active in most assays. The aqueous extract from Mutisia kurtzii caused a clear increase of the hsp72 production and showed prooxidant activity.     

Leishmania amazonensis META2 protein confers protection against heat shock and oxidative stress

The META cluster of Leishmania amazonensis contains both META1 and META2 genes, which are upregulated in metacyclic promastigotes and encode proteins containing the META domain. Previous studies defined META2 as a 48.0-kDa protein, which is conserved in other Leishmania species and in Trypanosoma brucei. In this work, we demonstrate that META2 protein expression is regulated during the Leishmania life cycle but constitutive in T. brucei. META2 protein is present in the cytoplasm and flagellum of L. amazonensis promastigotes. Leishmania META2-null replacement mutants are more sensitive to oxidative stress and, upon heat shock, assume rounded morphology with shortened flagella. The increased susceptibility of null parasites to heat shock is reversed by extra-chromosomal expression of the META2 gene. Defective Leishmania promastigotes exhibit decreased ability to survive in macrophages. By contrast, META2 expression is decreased by 80% in RNAi-induced T. brucei bloodstream forms with no measurable effect on survival or resistance to heat shock.     

Iso-mukaadial acetate and ursolic acid acetate inhibit the chaperone activity of Plasmodium falciparum heat shock protein 70-1

Plasmodium falciparum is the most lethal malaria parasite. The present study investigates the interaction capabilities of select plant derivatives, iso-mukaadial acetate (IMA) and ursolic acid acetate (UAA), against P. falciparum Hsp70-1 (PfHsp70-1) using in vitro approaches. PfHsp70-1 facilitates protein folding in the parasite and is deemed a prospective antimalarial drug target. Recombinant PfHsp70-1 protein was expressed in E. coli BL21 cells and homogeneously purified by affinity chromatography. The interaction between the compounds and PfHsp70-1 was evaluated using malate dehydrogenase (MDH), and luciferase aggregation assay, ATPase activity assay, and Fourier transform infrared (FTIR). PfHsp70-1 prevented the heat-induced aggregation of MDH and luciferase. However, the PfHsp70-1 chaperone role was inhibited by IMA or UAA, leading to both MDH and luciferase’s thermal aggregation. The basal ATPase activity of PfHsp70-1 (0.121 nmol/min/mg) was closer to UAA (0.131 nmol/min/mg) (p = 0.0675) at 5 mM compound concentration, suggesting that UAA has no effect on PfHsp70-1 ATPase activity. However, ATPase activity inhibition was similar between IMA (0.068 nmol/min/mg) (p < 0.0001) and polymyxin B (0.083 nmol/min/mg) (p < 0.0001). The lesser the Pi values, the lesser ATP hydrolysis observed due to compound binding to the ATPase domain. FTIR spectra analysis of IMA and UAA resulted in PfHsp70-1 structural alteration for β-sheets shifting the amide I band from 1637 cm⁻¹ to 1639 cm⁻¹, and for α-helix from 1650 cm⁻¹ to 1652 cm⁻¹, therefore depicting secondary structural changes with an increase in secondary structure percentage suggesting that these compounds interact with PfHsp70-1.Supplementary InformationThe online version contains supplementary material available at 10.1007/s12192-021-01212-6.     

Protein synthesis patterns following stage-specific heat shock in early Drosophila embryos

Summary Very short heat shocks are administered to carefully staged early embryos of Drosophila melanogaster, and the effects on protein synthesis pattern investigated. A shock as short as 2 min will induce the heat shock response (reduction of normal protein synthesis, increased synthesis of the heat shock proteins) in syncytial blastoderm or later stages. Thus the initial events of the heat shock response must occur within 2 min, and not reverse upon rapid return to 22° C. A low level of synthesis of the 70 kDa heat shock protein is sometimes visible in unshocked animals, but may be induced by the labeling procedure. Survival following a short shock is not strictly correlated with a high level of heat shock response. Pre-blastoderm embryos do not produce significant heat shock protein, but survive a 2 min 43°C heat shock better than do heat shock response competent blastoderm embryos. The protein synthesis pattern prior to the blastoderm stage is very stable, possibly enhancing survival following a short shock. Shocks of 3 min or longer are more detrimental to pre-blastoderm embryos than to later stages, confirming the role of the heat shock response in survival following a longer shock. Stage-specific developmental defects (phenocopies) may be induced by heat shock at the blastoderm or later stages. Induction of these defects may require disruption of the normal protein synthesis pattern. Use of very short heat shocks to induce the heat shock response will be valuable in identifying the precise time at which a specific defect can be induced.     

RelA-independent (p)ppGpp accumulation and heat shock protein induction after salt stress in Bacillus subtilis

Abstract Sodium chloride treatment triggered the accumulation of (p)ppGpp in the Bacillus subtilis relA ⁺ strain IS58 as well as in its relaxed counterpart IS56 . Besides this relA -independent (p)ppGpp induction the GTP and ATP pools decreased dramatically.
In previous papers we found a direct correlation between (p)ppGpp accumulation and stress protein induction. In B. subtilis relA the (p)ppGpp accumulation was accompanied by the induction of general stress proteins whose synthesis rates were also enhanced by heat stress, amino acid limitation or oxygen starvation. Specific heat shock proteins were not induced by salt stress.
We suggest that these general stress proteins are induced under non-growing conditions in general.     

Light and the recovery from heat shock induce the synthesis of 38 kDa mitochondrial proteins in Neurospora crassa

The effect of light on the protein synthesis pattern in the mitochondria of Neurospora crassa was examined by in vivo labelling with [³⁵S]-methionine and two-dimensional gel electrophoresis. A brief 5-min illumination induced the rapid and transient synthesis of a 38-kDa protein. White collar-mutants were not stimulated to synthesize this protein by light. A protein of a similar molecular weight and isoelectrical point was synthesized during recovery from heat shock.     

The heat shock proteins: Their roles as multi-component machines for protein folding

The roles played by heat shock proteins in fungi have been subjected to intense scrutiny. Presuming they only played roles in tolerance to stress gave way to the realization that many of them were essential for maintenance of cell physiology under all conditions. Recent progress has revealed their action as multi-component machines, playing roles in signalling and expansion of phenotypic plasticity, as well as their well-established function as molecular chaperones.     

Cold stenothermal cave-dwelling beetles do have an HSP70 heat shock response

The response to high temperatures in adults of two cold stenothermal cave-dwelling leptodirins, Neobathyscia mancinii and Neobathyscia pasai (Coleoptera, Cholevidae) was evaluated by determinating levels of gene expression of two members of the family of heat shock proteins 70 kDa by qPCR. In both species, hsc70 mRNA level was constant with increasing temperature, whereas a significant increase in the inducible member (hsp70) mRNA was observed, higher in N. pasai. This difference could be due to their in-cave distribution: N. pasai colonizes the cave entrance where the temperature is more variable than the internal part where N. mancinii is confined. These results demonstrated for the first time the occurrence of a heat shock response in troglobite insects and suggest the correlation between the intensity of this response and the adaptation to the cave environment.     

热休克蛋白27在胃癌的表达及意义

目的探讨热休克蛋白27(HSP27)在胃癌及癌旁组织中的表达及其意义。方法用免疫组织化学法检测68例胃癌及57例癌旁组织中HSP27的表达,比较其阳性表达率。结果HSP27在胃癌中的表达率为47.1%,明显高于癌旁组织26.32%(P<0.05),并且与胃癌的分化程度相关,但与肌层浸润深度及淋巴结转移无关。结论HSP27在胃癌组织中过度表达,提示其在胃癌的发生发展中起着重要作用。     

Basic features of the Staphylococcal heat shock response

The major heat shock proteins of Staphylococcus aureus had apparent M_rs of 84,000, 76,000, and 60,000, and other prominent proteins of M_rs 66,000, 51,000, 43,000 and 24,000 were also induced. Staphylococcus epidermidis showed a similar response. These proteins were also induced by CdCl₂, ethanol and apparently osmotic stress (1.71 M NaCl or 2.25 M sucrose). Most of the proteins sedimented with the membrane fraction, but the M_r 60,000 protein remained in the cytoplasm.     

Developmental study of thermotolerance and the heat shock response inLucilia cuprina (Weidemann)

The ability to withstand thermal stress in a laboratory population of the blowflyLucilia cuprina (measured as per cent adult survival following varying periods of exposure to elevated temperature up to a maximum of 48°C) was in the order pupa > larva > adult. Pre-exposure to a mild heat shock (37°C) induced tolerance to temperatures which were otherwise lethal. An analysis of heat shock-induced protein synthesis during development at similar elevated temperatures presented patterns corresponding to the above observations on thermotolerance. The induced level of synthesis of major heat shock proteins (viz., 79, 69, 28, 20 and 19 kDa) were greater in larval tissues than in most of the adult tissues except gonads. The response varied between young (2 days) and old (30 days) adults in a tissue-specific manner. In general, heat shock protein 69 kDa was most abundant in all the tissues studied. Control as well as heat shocked Malpighian tubules of adults uniquely showed two major [³⁵S]methionine labelled bands corresponding to approximately 62 and 64 kDa. Immunoblots showed the 62 kDa protein to cross react with an antibody againstHelioihis HSP60. Although the synthesis of the 62 kDa polypeptide was prominent only in Malpighian tubules of adult blowflies, nearly equal levels of this HSP60 family polypeptide were present in all tissues (control as well heat shocked) except the larval salivary glands.     

A rubrerythrin-like oxidative stress protein of Clostridium acetobutylicum is encoded by a duplicated gene and identical to the heat shock protein Hsp21

Comparison of the N-terminus of the heat shock protein Hsp21 of Clostridium acetobutylicum with proteins predicted to be encoded by the genome of this bacterium revealed that this stress protein is encoded by two almost identical open reading frames CAC3597 and CAC3598. These genes encode a rubrerythrin-like protein with the rubredoxin-like FeS4 domain at the N-terminus and the ferritin-like diiron domain (rubrerythrin domain) at the C-terminus. Thus, the order of the two putative functional domains is reversed compared to "normal" rubrerythrins. This protein is proposed to be involved in the oxidative stress response of strict anaerobic bacteria. Northern blot analysis indicated that hsp21 is induced by heat and oxidative stress (air, H2O2). Hsp21 of C. acetobutylicum can be considered as a "reverse" rubrerythrin and a role of this stress protein, which is conserved among clostridia and other strict anaerobic bacteria, in the heat and oxidative stress response is proposed.     

Proteomic analysis of small heat shock protein isoforms in barley shoots

The analysis of stress-responsiveness in plants is an important route to the discovery of genes conferring stress tolerance and their use in breeding programs. High temperature is one of the environmental stress factors that can affect the growth and quality characteristics of barley (Hordeum vulgare). In this study a proteomic analysis (2D-PAGE, MS) was used to detect the effects of heat shock on the protein pattern of an abiotic stress-tolerant (Mandolina) and an abiotic stress-susceptible (Jubilant) barley cultivar. Evaluation of two-dimensional gels revealed several proteins to be differentially expressed as a result of heat stress in both cultivars. The protein spots of interest were, after an in-gel tryptic digestion, further investigated by mass spectrometry. For the analysis of the peptide mixture, we both used a matrix-assisted laser desorption/ionization (MALDI) tandem time of flight mass spectrometer (TOF/TOF) and an automated nano-HPLC system coupled to an electrospray ionization-quadrupole linear ion trap (Q-TRAP) instrument. The hyphenation of the latter techniques proved to be a powerful technique as shown by the identification of six isoforms of a 16.9 kDa sHSP in one single spot. We observed that S-adenosylmethionine synthetase (SAM-S) was differentially expressed between the two cultivars. Recent results refer to the role of SAM-S as being involved in abiotic stress tolerance. Furthermore, comparison of the heat shock treated samples also revealed several small heat shock proteins (sHSP), of which distinct isoforms could be characterised.