Small heat shock proteins and α-crystallins: dynamic proteins with flexible functions

'Re-Wilding' an Animal Model With Microbiota Shifts Immunity and Stress Gene Expression During Infection

The frequency of emerging disease is growing with ongoing human activity facilitating new host-pathogen interactions. Novel infection outcomes can also be shaped by the host microbiota. Caenorhabditis elegans nematodes experimentally colonised by a wild microbiota community and infected by the widespread animal pathogen, Staphylococcus aureus, have been shown to suffer higher mortality than those infected by the pathogen alone. Understanding the host responses to such microbiota-pathogen ecological interactions is key to pinpointing the mechanism underlying severe infection outcomes. We conducted transcriptomic analyses of C. elegans colonised by its native microbiota, S. aureus and both in combination. Correlations between altered collagen gene expression and heightened mortality in co-colonised hosts suggest the microbiota modified host resistance to infection. Furthermore, microbiota colonised hosts showed increased expression of immunity genes and variable expression of stress response genes during infection. Changes in host immunity and stress response could encompass both causes and effects of severe infection outcomes. 'Re-wilding' this model nematode host with its native microbiota indicated that typically commensal microbes can mediate molecular changes in the host that are costly when challenged by a novel emerging pathogen.

A microaerobically induced small heat shock protein contributes to Rhizobium leguminosarum/Pisum sativum symbiosis and interacts with a wide range of bacteroid proteins

During the establishment of the symbiosis with legume plants, rhizobia are exposed to hostile physical and chemical microenvironments to which adaptations are required. Stress response proteins including small heat shock proteins (sHSPs) were previously shown to be differentially regulated in bacteroids induced by Rhizobium leguminosarum bv. viciae UPM791 in different hosts. In this work, we undertook a functional analysis of the host-dependent sHSP RLV_1399. A rlv_1399-deleted mutant strain was impaired in the symbiotic performance with peas but not with lentil plants. Expression of rlv_1399 gene was induced under microaerobic conditions in a FnrN-dependent manner consistent with the presence of an anaerobox in its regulatory region. Overexpression of this sHSP improves the viability of bacterial cultures following exposure to hydrogen peroxide and to cationic nodule-specific cysteine-rich (NCR) antimicrobial peptides. Co-purification experiments have identified proteins related to nitrogenase synthesis, stress response, carbon and nitrogen metabolism, and to other relevant cellular functions as potential substrates for RLV_1399 in pea bacteroids. These results, along with the presence of unusually high number of copies of shsp genes in rhizobial genomes, indicate that sHSPs might play a relevant role in the adaptation of the bacteria against stress conditions inside their host.IMPORTANCEThe identification and analysis of the mechanisms involved in host-dependent bacterial stress response is important to develop optimal Rhizobium/legume combinations to maximize nitrogen fixation for inoculant development and might have also applications to extend nitrogen fixation to other crops. The data presented in this work indicate that sHSP RLV_1399 is part of the bacterial stress response to face specific stress conditions offered by each legume host. The identification of a wide diversity of sHSP potential targets reveals the potential of this protein to protect essential bacteroid functions. The finding that nitrogenase is the most abundant RLV_1399 substrate suggests that this protein is required to obtain an optimal nitrogen-fixing symbiosis.

Anti-aggregation Properties of the Mini-Peptides Derived from Alpha Crystallin Domain of the Small Heat Shock Protein, Tpv HSP 14.3

The highly conserved alpha crystallin domain of the small heat shock proteins is essential for dimerization and also implicated in substrate interaction. In this study, we designed four novel mini-peptides from alpha crystallin domain of archaeal Small Heat Shock Protein Tpv HSP 14.3. Among the peptide designs, the mini-peptides 38SDLVLEAEMAGFDKKNIKVS57 and 40LVLEAEMAGFD50 overlapped to the sequences of β3-β4 region. The other two peptides 77YIDQRVDKVYKVVKLPVE94 and 107GILTVRMK114 correspond to β6-β7 region and β9, respectively. Functional activity of the peptides was evaluated by monitoring heat-induced aggregation of the model substrates alcohol dehydrogenase at 43 °C and citrate synthase at 45 °C. Our results showed that the (38-57) and the (77-94) fragments exhibited chaperone activity with both of the substrate proteins. The (40-50) fragment while exhibiting a noticeable protective effect (> 90%) when tested with citrate synthase showed an anti-chaperone property toward alcohol dehydrogenase. Unlike the (40-50) fragment, the (107-114) fragment did not show any chaperone activity with citrate synthase but exhibited the highest chaperone efficiency among four mini-peptides with alcohol dehydrogenase. The selectivity of the (40-50) and the (107-114) fragments in targeting the client proteins is most likely dependent on their surface hydrophobicity and/or charge as revealed by the sequence and exposed surface analyses.

A TT1-SCE1 module integrates ubiquitination and SUMOylation to regulate heat tolerance in rice

Heat stress poses a significant threat to grain yield. As an α2 subunit of the 26S proteasome, TT1 has been shown to act as a critical regulator of rice heat tolerance. However, the heat tolerance mechanisms mediated by TT1 remain elusive. In this study, we unveiled that small ubiquitin-like modifier (SUMO)-conjugating enzyme 1 (SCE1), which interacts with TT1 and acts as a downstream component of TT1, is engaged in TT1-mediated 26S proteasome degradation. We showed that SCE1 functions as a negative regulator of heat tolerance in rice, which is associated with its ubiquitination modification. Furthermore, we observed that small heat-shock proteins (sHSPs) such as Hsp24.1 and Hsp40 can undergo SUMOylation mediated by SCE1, leading to increased accumulation of sHSPs in the absence of SCE1. Reducing protein levels of SCE1 significantly enhanced grain yield under high-temperature stress by improving seed-setting rate and rice grain filling capacity. Taken together, these results uncover the critical role of SCE1 in the TT1-mediated heat tolerance pathway by regulating the abundance of sHSPs and SUMOylation, and ultimately modulating rice heat tolerance. These findings underscore the great potential of the TT1-SCE1 module in improving the heat tolerance of crops.

Genome-wide identification and expression analysis of the heat shock protein gene superfamily in Hylurgus ligniperda

Hylurgus ligniperda belongs to Hylurgus Latreille, Curculionidae, Coleoptera. It primarily damages the base and roots of the trunk of pine plants. Short-term treatment at 42 °C can damage Hylurgus ligniperda; therefore, temperature is a vital factor limiting its spread. Heat shock proteins (HSPs) can protect, remove, and repair proteins to help H. ligniperda withstand high temperatures. However, information on HSP genes in H. ligniperda remains limited. In the study, we considered H. ligniperda as the focus of research and identified 56 HligHSP genes at the genome-wide level. These genes were mapped to the cytoplasm or nucleus. An identical subfamily exhibited a closely similar distribution of conserved domains. Combined with the transcriptome data collected in previous studies, we screened six candidate genes, namely HligsHSP-3, HligsHSP-4, HligHSP60-16, HligHSP70-3, HligHSP70-4, and HligHSP90-1, which are specifically expressed during different high-temperature treatments. A quantitative polymerase chain reaction was performed to measure the expression of these six HligHSPs in seven temperature treatment conditions. These genes may be involved in the heat resistance mechanism in adults. Our findings provided a foundation for further studying the heat resistance mechanism in H. ligniperda.

Artemin molecular chaperone from Artemia urmiana improves tolerance of Arabidopsis thaliana to abiotic stress

Artemia is a genus of aquatic microcrustaceans that belong to the class Branchiopoda. Encysted Artemia urmiana embryos are resistant to harsh environmental stressors, including repeated desiccation, prolonged anoxia, extreme temperatures, and high levels of UV radiation. The protein artemin has a chaperone activity and is believed to play a crucial role in protecting the organism against such stresses. To elucidate the potential functional roles of artemin in plants, the cDNA sequence of artemin was cloned into the pZPY122 binary plant expression vector. Agrobacterium -mediated transformation and the floral-dip technique were used to introduce this construct into Arabidopsis thaliana . Three independent transgenic lines (art1 , art2 , art3 ) were generated and subjected to heat stress at 45°C. Results showed a significant interaction between heat stress and genotype for germination rate, germination speed, vigor index, and seedling and root length. The transgenic lines with the artemin transgene (ART ) exhibited remarkable heat stress tolerance compared with wild-type plants. They also had markedly lower levels of electrolyte leakage, hydrogen peroxide content, higher activities of catalase, superoxide dismutase and peroxidase, greater total protien content, and increased accumulation of proline. Under heat stress conditions, the expression of two key abiotic stress-responsive genes, DREB2A and HSFA3 , was significantly upregulated in the ART lines compared to the wild-type . These findings suggest that the ART gene from A. urmiana may act as molecular chaperone when expressed in Arabidopsis , thereby enhancing the plant's tolerance to heat stress.

A small heat shock protein (SlHSP17.3) in tomato plays a positive role in salt stress

Small heat shock proteins (sHSPs) are molecular chaperones that are widely present in plants and play a vital role in the response of plants to various environmental stimuli. This study employed transgenic Arabidopsis to investigate the impact of the new tomato (Solanum lycopersicum) sHSP protein (SlHSP17.3) on salt stress tolerance. Transient conversion analysis of Arabidopsis protoplasts revealed that SlHSP17.3 localized to the cytoplasm. Furthermore, as suggested by expression analysis, salt stress stimulated SlHSP17.3 expression, suggesting that SlHSP17.3 is involved in the salt stress response of plants. SlHSP17.3-overexpressing plants presented greater germination rates, fresh weights, chlorophyll contents, and Fv/Fm ratios, as well as longer root lengths, lower reactive oxygen species (ROS) levels, and lighter cell membrane injury under salt stress. Furthermore, certain stress-related genes (AtCOR15, AtDREB1B, and AtHSFA2) were up-regulated in salt-stressed transgenic plants. Overall, SlHSP17.3 overexpression improved the salt stress resistance of transgenic plants, mainly through increasing AtCOR15, AtDREB1B, and AtHSFA2 expression.

Mechanisms of transcriptional regulation in Anopheles gambiae revealed by allele-specific expression

Malaria control relies on insecticides targeting the mosquito vector, but this is increasingly compromised by insecticide resistance, which can be achieved by elevated expression of detoxifying enzymes that metabolize the insecticide. In diploid organisms, gene expression is regulated both in cis, by regulatory sequences on the same chromosome, and by trans acting factors, affecting both alleles equally. Differing levels of transcription can be caused by mutations in cis-regulatory modules (CRM), but few of these have been identified in mosquitoes. We crossed bendiocarb-resistant and susceptible Anopheles gambiae strains to identify cis-regulated genes that might be responsible for the resistant phenotype using RNAseq, and CRM sequences controlling gene expression in insecticide resistance relevant tissues were predicted using machine learning. We found 115 genes showing allele-specific expression (ASE) in hybrids of insecticide susceptible and resistant strains, suggesting cis-regulation is an important mechanism of gene expression regulation in A. gambiae. The genes showing ASE included a higher proportion of Anopheles-specific genes on average younger than genes with balanced allelic expression.

LrHSP17.2 Plays an Important Role in Abiotic Stress Responses by Regulating ROS Scavenging and Stress-Related Genes in Lilium regale

As an important part of heat shock response module, heat shock proteins (HSP) play an important role in plant defense response against heat stress; however, the involvement of the majority of the HSP family members against other abiotic stresses remains poorly understood. In the present study, LrHSP17.2 was identified and its function against abiotic stress was analyzed. The expression level of LrHSP17.2 was significantly induced by heat. Heterologous transgenes of LrHSP17.2 showed that LrHSP17.2 can increase the activity of catalase, peroxidase, superoxide dismutase to removes excess reactive oxygen species (ROS), maintain the stability of the membrane structure, and regulate genes related to antioxidant enzymes and defense under abiotic stress. In addition, LrHSP17.2 could be regulated by exogenous abscisic acid and melatonin, and the related hormone synthesis genes of transgenic plants were significantly up-regulated under heat stress. Taken together, our results revealed that LrHSP17.2 is involved in regulating abiotic stress responses by regulating ROS scavenging and stress-related genes in Lilium regale.

N-acetylcysteine stimulates the proliferation and differentiation in heat-stressed skeletal muscle cells

N-acetylcysteine (NAC) is known for its beneficial effects on health due to its antioxidant and antiapoptotic properties. This study explored the protective effects of NAC against oxidative stress in heat-stressed (HS) skeletal muscle cells and its role in promoting muscle development. NAC reduced the heat shock response by decreasing the expression of heat shock protein 70 (HSP70) in HS-induced muscle cells during proliferation and differentiation. NAC also mitigated HS-induced oxidative stress via increasing the antioxidant enzyme levels and reducing oxidant enzyme levels. Treatment with NAC at 2 mM increased cell viability from 43.68% ± 5.14%-66.69% ± 14.43% and decreased the apoptosis rate from 7.89% ± 0.53%-5.17% ± 0.11% in skeletal muscle cells. Additionally, NAC promoted the proliferation and differentiation of HS-induced skeletal muscle cells by upregulating the expression of PAX7, MYF5, MRF4 and MYHC. These findings suggest that NAC alleviates HS-induced oxidative damage in skeletal muscle cells and support muscle development.

Explaining Conformational Diversity in Protein Families through Molecular Motions

Proteins play a central role in biological processes, and understanding their conformational variability is crucial for unraveling their functional mechanisms. Recent advancements in high-throughput technologies have enhanced our knowledge of protein structures, yet predicting their multiple conformational states and motions remains challenging. This study introduces Dimensionality Analysis for protein Conformational Exploration (DANCE) for a systematic and comprehensive description of protein families conformational variability. DANCE accommodates both experimental and predicted structures. It is suitable for analysing anything from single proteins to superfamilies. Employing it, we clustered all experimentally resolved protein structures available in the Protein Data Bank into conformational collections and characterized them as sets of linear motions. The resource facilitates access and exploitation of the multiple states adopted by a protein and its homologs. Beyond descriptive analysis, we assessed classical dimensionality reduction techniques for sampling unseen states on a representative benchmark. This work improves our understanding of how proteins deform to perform their functions and opens ways to a standardised evaluation of methods designed to sample and generate protein conformations.

Proteomic characteristics of the aqueous humor in Uyghur patients with pseudoexfoliation syndrome and pseudoexfoliative glaucoma

Pseudoexfoliation syndrome (PEX) is characterized by the deposition of fibrous pseudoexfoliation material (PEXM) in the eye, and secondary glaucoma associated with this syndrome has a faster and more severe clinical course. The incidence of PEX and pseudoexfoliative glaucoma (PEXG) exhibits ethnic clustering; however, few proteomic studies related to PEX and PEXG have been conducted in Asian populations. Therefore, we aimed to conduct proteomic analysis on the aqueous humor (AH) obtained from Uyghur patients with cataracts, those with PEX and cataracts, and those with PEXG and cataracts to better understand the molecular mechanisms of the disease and identify its potential biomarkers. To this end, AH was collected from patients with cataracts (n = 10, control group), PEX with cataracts (n = 10, PEX group), and PEXG with cataracts (n = 10, PEXG group) during phacoemulsification. Label-free quantitative proteomic techniques combined with bioinformatics were used to identify and analyze differentially expressed proteins (DEPs) in the AH of PEX and PEXG groups. Then, independent AH samples (n = 12, each group) were collected to validate DEPs by enzyme-linked immunosorbent assay (ELISA). The PEX group exhibited 25 DEPs, while the PEXG group showed 44 DEPs, both compared to the control group. Subsequently, we found three newly identified proteins in both PEX and PEXG groups, wherein FRAS1-related extracellular matrix protein 2 (FREM2) and osteoclast-associated receptor (OSCAR) exhibited downregulation, whereas coagulation Factor IX (F9) displayed upregulation. Bioinformatics analysis suggested that extracellular matrix interactions, abnormal blood-derived proteins, and lysosomes were mainly involved in the process of PEX and PEXG, and the PPI network further revealed F9 may serve as a potential biomarker for both PEX and PEXG. In conclusion, this study provides new information for understanding the proteomics of AH in PEX and PEXG.

The small heat shock protein Hsp20.8 imparts tolerance to high temperatures in the leafminer fly, Liriomyza trifolii (Diptera: Agtomyzidae)

As an environmental factor, temperature impacts the distribution of species and influences interspecific competition. The molecular chaperones encoded by small heat shock proteins (sHsps) are essential for rapid, appropriate responses to environmental stress. This study focuses on Hsp20.8, which encodes a temperature-responsive sHsp in Liriomyza trifolii, an insect pest that infests both agricultural and ornamental crops. Hsp20.8 expression was highest at 39℃ in L. trifolii pupae and adults, and expression levels were greater in pupae than in adults. Recombinant Hsp20.8 was expressed in Escherichia coli and conferred a higher survival rate than the empty vector to bacterial cells exposed to heat stress. RNA interference experiments were conducted using L. trifolii adults and prepupae and the knockdown of Hsp20.8 expression increased mortality in L. trifolii during heat stress. The results expand our understanding of sHsp function in Liriomyza spp. and the ongoing adaptation of this pest to climate change. In addition, this study is also important for predicting the distribution of invasive species and proposing new prevention and control strategies based on temperature adaptation.

Heat shock protein (Hsp27)-ceramide synthase (Cers1) protein-protein interactions provide a new avenue for unexplored anti-cancer mechanism and therapy

Hsp27 is a member of the small heat-shock proteins (sHSPs) - the known cellular line of defence against abnormal protein folding behaviors. Nevertheless, its upregulation is linked to a variety of pathological disorders, including several types of cancers. The ceramide synthases (CerS) mediate the synthesis of ceramide, a critical structural and signaling lipid. Functionally, downstream ceramide metabolites are implicated in the apoptosis process and their abnormal functionality has been linked to anticancer resistance. Studies showed that CerS1 are possibly inhibited by Hsp27 leading to biochemical anticancer effects in vitro. Nevertheless, the nature of such protein-protein interaction (PPI) has not been considerably investigated in molecular terms, hence, we present the first description of the dynamics CerS1-Hsp27 interaction landscapes using molecular dynamics simulations. Time-scale molecular dynamics simulation analysis indicated a system-wide conformational events of decreased stability, increased flexibility, reduced compactness, and decreased folding of CerS1. Analysis of binding energy showed a favorable interaction entailing 56 residues at the interface and a total stabilizing energy of -158 KJ/mol. The CerS1 catalytic domain experienced an opposite trend compared to the protein backbone. Yet, these residues adopted a highly compact conformation as per DCCM and DSSP analysis. Furthermore, conserved residues (SER 212, ASP 213, ALA 240, GLY 243, ASP 319) comprising the substrate shuttling machinery showed notable rigidity implying a restrained ceramide precursor access and assembly; hence, a possible inhibitory mechanism. Findings from this report would streamline a better molecular understanding of CerS1-Hsp27 interactions and decipher its potential avenue toward unexplored anti-cancer mechanisms and therapy.

Understanding the structural and functional changes and biochemical pathomechanism of the cardiomyopathy-associated p.R123W mutation in human αB-crystallin

αB-crystallin, a member of the small heat shock protein (sHSP) family, is expressed in diverse tissues, including the eyes, brain, muscles, and heart. This protein plays a crucial role in maintaining eye lens transparency and exhibits holdase chaperone and anti-apoptotic activities. Therefore, structural and functional changes caused by genetic mutations in this protein may contribute to the development of disorders like cataract and cardiomyopathy. Recently, the substitution of arginine 123 with tryptophan (p.R123W mutation) in human αB-crystallin has been reported to trigger cardiomyopathy. In this study, human αB-crystallin was expressed in Escherichia coli (E. coli), and the missense mutation p.R123W was created using site-directed mutagenesis. Following purification via anion exchange chromatography, the structural and functional properties of both proteins were investigated and compared using a wide range of spectroscopic and microscopic methods. The p.R123W mutation induced significant alterations in the secondary, tertiary, and quaternary structures of human αB-crystallin. This pathogenic mutation resulted in an increased β-sheet structure and formation of protein oligomers with larger sizes compared to the wild-type protein. The mutant protein also exhibited reduced chaperone activity and lower thermal stability. Atomic force microscopy (AFM) and transmission electron microscopy (TEM) demonstrated that the p.R123W mutant protein is more prone to forming amyloid aggregates. The structural and functional changes observed in the p.R123W mutant protein, along with its increased propensity for aggregation, could impact its proper functional interaction with the target proteins in the cardiac muscle, such as calcineurin. Our results provide an explanation for the pathogenic intervention of p.R123W mutant protein in the occurrence of hypertrophic cardiomyopathy (HCM).

The MBD-ACD DNA methylation reader complex recruits MICRORCHIDIA6 to regulate ribosomal RNA gene expression in Arabidopsis

DNA methylation is an important epigenetic mark implicated in selective rRNA gene expression, but the DNA methylation readers and effectors remain largely unknown. Here, we report a protein complex that reads DNA methylation to regulate variant-specific 45S ribosomal RNA (rRNA) gene expression in Arabidopsis (Arabidopsis thaliana). The complex, consisting of METHYL-CpG-BINDING DOMAIN PROTEIN5 (MBD5), MBD6, ALPHA-CRYSTALLIN DOMAIN PROTEIN15.5 (ACD15.5), and ACD21.4, directly binds to 45S rDNA. While MBD5 and MBD6 function redundantly, ACD15.5 and ACD21.4 are indispensable for variant-specific rRNA gene expression. These 4 proteins undergo phase separation in vitro and in vivo and are interdependent for their phase separation. The α-crystallin domain of ACD15.5 and ACD21.4, which is essential for their function, enables phase separation of the complex, likely by mediating multivalent protein interactions. The effector MICRORCHIDIA6 directly interacts with ACD15.5 and ACD21.4, but not with MBD5 and MBD6, and is recruited to 45S rDNA by the MBD-ACD complex to regulate variant-specific 45S rRNA expression. Our study reveals a pathway in Arabidopsis through which certain 45S rRNA gene variants are silenced, while others are activated.

Comprehensive analysis of Dendrobium catenatum HSP20 family genes and functional characterization of DcHSP20-12 in response to temperature stress

Heat shock proteins (HSPs) are a class of protective proteins in response to abiotic stress in plants, and HSP20 plays an essential role in response to temperature stress. However, there are few studies on HSP20 in Dendrobium catenatum. In this study, 18 DcHSP20 genes were identified from the D. catenatum genome. Phylogenetic analysis showed that DcHSP20s could be classified into six subgroups, each member of which has similar conserved motifs and gene structures. Gene expression analysis of 18 DcHSP20 genes revealed that they exhibited variable expression patterns in different plant tissues. Meanwhile, all 18 DcHSP20 genes were induced to be up-regulated under high temperature, while six genes (DcHSP20-2/9/10/12/16/17) were significantly up-regulated under low temperature. Moreover, combining gene expression under high and low temperature stress, the DcHSP20-12 gene was cloned for functional analysis. The germination ratios, fresh weights, root lengths of two DcHSP20-12-overexpressing transgenic Arabidopsis thaliana lines were significantly higher, but MDA contents were lower than that of wild-type (WT) plants under heat and cold stresses, displayed enhanced thermotolerance and cold-resistance. These results lay a foundation for the functional characterization of DcHSP20s and provide a candidate gene, DcHSP20-12, for improving the tolerance of D. catenatum to temperature stress in the future.

Effects of small heat shock proteins from thermotolerant bacteria on the stress resistance of Escherichia coli to temperature, pH, and hyperosmolarity

Small heat shock proteins (HSPs), such as HSP20, represent cellular thermal resistance mechanisms, to avoid protein aggregation at elevated temperatures. Recombinantly expressed HSP20s serve as a molecular tool for improving the tolerance of living cells to various physical and chemical stressors. Here, we aimed to heterologously express 18 HSP20s from 12 thermotolerant bacteria in Escherichia coli and evaluate their effects on various physical and chemical cellular stresses. Seventeen HSP20s were successfully expressed as soluble proteins. Recombinant E. coli cells were subjected to heat, cold, acidic, alkaline, and hyperosmolar stress to evaluate the effects of HSP20 proteins on stress resistance. Notably, the overexpression of 15 HSP20s enhanced the stress resistance of E. coli compared to that of the control strain. In particular, HSPs from Tepidimonas sediminis and Oceanithermus profundus improved the stress tolerance of E. coli under all tested conditions. In addition, E. coli harboring HSP20 from T. sediminis retained cell viability even after heat treatment at 52 °C for 5 days. To our knowledge, this is the first report of E. coli tolerance to prolonged (> 100 h) high-temperature stress. These findings indicate the potential of thermotolerant HSPs as molecular tools for improving stress tolerance in E. coli.

Alterations in Histone Methylation States Increased Profusion of Lethal(2)-Essential-for-Life-Like (l(2)elf), Trithorax and Polycomb Genes in Apis mellifera under Heat Stress

Histone post-translational modifications (PTMs) represent a key mechanism in the thermal adaptation of the honeybee Apis mellifera. In this study, a chromatin immunoprecipitation assay and qPCR were employed to explore the changes in the methylation states of H3K4m2, H3K4m3, H3K27m2 and H3K27m3 associated with l2efl (ID: 72474, 724405, 724488), histone methyltransferases (HMTs) ((trx) and PR-set7) and Polycomb (Pc) and (Su(z)12) genes in A. m. jemenitica (tolerant subspecies) and A. m. carnica (susceptible subspecies) in response to heat treatment (42 °C for 1 h). The results revealed significant enrichment fold changes in the methylation/demethylation of most H3K4 and H3K27 marks at all targeted genes. These changes increased the profusion of l2efl (ID: 72474, 724405, 724488), histone methyltransferases (HMTs) (trx) and Polycomb (Pc) and Su(z)12 and decreased the profusion of HMT (PR-set7) in both honeybee subspecies. The changes in the methylation enrichment folds of histone methyltransferases (HMTs) ((trx), PR-set) and Polycomb (Pc), Su(z)12 genes demonstrate the well-harmonized coordination of epigenetic gene regulation in response to heat treatment. Compared to the control, the changes in the methylation enrichment folds of H3K4m3 at Polycomb Su(z)12 were about 30× and 100× higher in treated A. m. jemenitica and A.m. carnica, respectively. Similarly, changes in the methylation/demethylation enrichment folds of HMT (trx) and Polycomb (Pc) and Su(z)12 were 2-3× higher in A. m. carnica than in A. m. jemenitica after treatment (42 °C). It is evident that post-translational chromatin modification in both honeybee subspecies can diminish heat stress impact by (I) increasing the transcriptional provision of l2efl associated with survival and (II) increasing the silencing of genes associated with general cellular activities.

A DUF3494 ice-binding protein with a root cap domain in a streptophyte glacier ice alga

Ice-binding proteins (IBPs) of the DUF3494 type have been found in many ice-associated unicellular photoautotrophs, including chlorophytes, haptophytes, diatoms and a cyanobacterium. Unrelated IBPs have been found in many land plants (streptophytes). Here we looked for IBPs in two streptophyte algae that grow only on glaciers, a group in which IBPs have not previously been examined. The two species, Ancylonema nordenskioeldii and Ancylonema. alaskanum, belong to the class Zygnematophyceae, whose members are the closest relatives to all land plants. We found that one of them, A. nordenskioeldii, expresses a DUF3494-type IBP that is similar to those of their chlorophyte ancestors and that has not previously been found in any streptophytes. The protein is unusual in having what appears to be a perfect array of TXT motifs that have been implicated in water or ice binding. The IBP strongly binds to ice and almost certainly has a role in mitigating the daily freeze-thaw cycles that the alga is exposed to during late summer. No IBP was found in the second species, A. alaskanum, which may rely more on glycerol production for its freeze-thaw tolerance. The IBP is also unusual in having a 280-residue domain with a β sandwich structure (which we designate as the DPH domain) that is characteristic of root cap proteins of land plants, and that may have a role in forming IBP oligomers. We also examined existing transcriptome data obtained from land plants to better understand the tissue and temperature dependence of expression of this domain.

Chromosome-level genome of the poultry shaft louse Menopon gallinae provides insight into the host-switching and adaptive evolution of parasitic lice

BACKGROUND

Lice (Psocodea: Phthiraptera) are one important group of parasites that infects birds and mammals. It is believed that the ancestor of parasitic lice originated on the ancient avian host, and ancient mammals acquired these parasites via host-switching from birds. Here we present the first chromosome-level genome of Menopon gallinae in Amblycera (earliest diverging lineage of parasitic lice). We explore the transition of louse host-switching from birds to mammals at the genomic level by identifying numerous idiosyncratic genomic variations.

RESULTS

The assembled genome is 155 Mb in length, with a contig N50 of 27.42 Mb. Hi-C scaffolding assigned 97% of the bases to 5 chromosomes. The genome of M. gallinae retains a basal insect repertoire of 11,950 protein-coding genes. By comparing the genomes of lice to those of multiple representative insects in other orders, we discovered that gene families of digestion, detoxification, and immunity-related are generally conserved between bird lice and mammal lice, while mammal lice have undergone a significant reduction in genes related to chemosensory systems and temperature. This suggests that mammal lice have lost some of these genes through the adaption to environment and temperatures after host-switching. Furthermore, 7 genes related to hematophagy were positively selected in mammal lice, suggesting their involvement in the hematophagous behavior.

CONCLUSIONS

Our high-quality genome of M. gallinae provides a valuable resource for comparative genomic research in Phthiraptera and facilitates further studies on adaptive evolution of host-switching within parasitic lice.

The response of heat shock proteins in honey bees to abiotic and biotic stressors

Honey bees, Apis mellifera, are the most important managed pollinators worldwide. They are highly impacted by various abiotic and biotic stressors, especially temperature extremes, which can lead to cellular damage and death. The induction of heat shock proteins (HSPs) has been recorded in honey bees as a response to various types of stressors. HSPs are classified into different gene families according to their molecular weights. HSPs play an important role in maintaining cellular protein homeostasis due to their contribution as molecular chaperones or co-chaperones. HSPs in honey bees have complex functions with induction even under normal colony conditions. Previous studies have suggested various functions of HSPs to protect cells from damage under exposure to environmental stressors, pollutants, and pathogens. Surprisingly, HSPs have also been found to play roles in larval development and age-related tasks. The expression of HSPs varies depending on tissue type, developmental stage, age, and stress period. This article reviews studies on HSPs (sHSPs, HSP40, HSP60, HSP70, and HSP90) in honey bees and highlights gaps in the available knowledge. This review is crucial for honey bee research, particularly in the face of climate change challenges.

A subfamily of the small heat shock proteins of the marine red alga Neopyropia yezoensis localizes in the chloroplast

Small heat shock proteins (sHSPs) play a crucial role under abiotic stress and are present in all organisms, from eukaryotes to prokaryotes. However, studies on the sHSP gene family in red alga are limited. In this study, we aimed to identify and characterize NysHSP genes from the genome of N. yezoensis, a marine red alga adapted to the stressful intertidal zone. We identified seven NysHSP genes distributed on all three chromosomes. Expression analysis revealed that all NysHSP genes responded to H2O2 and heat stress in the gametophytic thalli, but these genes responded only to heat stress in the sporophytic conchocelis. NysHSP20.3, which has an acidic isoelectric point (pI) and short N-terminal region, was localized as granules in the cytosol. Fluorescence imaging of the NysHSP25.8-GFP and NysHSP28.4-GFP fusion proteins revealed that these proteins were located in the chloroplast. Based on their characteristics and cellular localization, the NysHSPs are divided into two subfamilies. Subfamily I includes four sHSP genes that strongly respond to heat stress and encode a protein localized in the cytosol. The NysHSP gene of subfamily II encodes a polypeptide with a long N-terminal region located in the chloroplast. This study provides insights into the evolution and function of the sHSP gene family of the marine red alga N. yezoensis and how it adapts to the stressful intertidal zone.

A review on oligomeric polydispersity and oligomers-dependent holding chaperone activity of the small heat-shock protein IbpB of Escherichia coli

Inclusion body-associated proteins IbpA and IbpB of MW 16 KDa are the two small heat-shock proteins (sHSPs) of Escherichia coli, and they have only holding, but not folding, chaperone activity. In vitro holdase activity of IbpB is more than that of IbpA, and in combination, they synergise. Both IbpA and IbpB monomers first form homodimers, which as building blocks subsequently oligomerize to make heavy oligomers with MW of MDa range; for IbpB, the MW range of heavy oligomers is 2.0-3.0 MDa, whereas for IbpA oligomers, the values in MDa are not so specified/reported. By temperature upshift, such large oligomers of IbpB, but not of IbpA, dissociate to make relatively small oligomeric assemblies of MW around 600-700KDa. The larger oligomers of IbpB are assumed to be inactive storage form, which on facing heat or oxidative stress dissociate into smaller oligomers of ATP-independent holding chaperone activity. These smaller oligomers bind with stress-induced partially denatured/unfolded and thereby going to be aggregated proteins, to give them protection against permanent damage and aggregation. On withdrawal of stress, IbpB transfers the bound substrate protein to the ATP-dependent bi-chaperone system DnaKJE-ClpB, having both holdase and foldase properties, to finally refold the protein. Of the two sHSPs IbpA and IbpB of E. coli, this review covers the recent advances in research on IbpB only.

The Functionality of IbpA from Acholeplasma laidlawii Is Governed by Dynamic Rearrangement of Its Globular-Fibrillar Quaternary Structure

Small heat shock proteins (sHSPs) represent a first line of stress defense in many bacteria. The primary function of these molecular chaperones involves preventing irreversible protein denaturation and aggregation. In Escherichia coli, fibrillar EcIbpA binds unfolded proteins and keeps them in a folding-competent state. Further, its structural homologue EcIbpB induces the transition of EcIbpA to globules, thereby facilitating the substrate transfer to the HSP70-HSP100 system for refolding. The phytopathogenic Acholeplasma laidlawii possesses only a single sHSP, AlIbpA. Here, we demonstrate non-trivial features of the function and regulation of the chaperone-like activity of AlIbpA according to its interaction with other components of the mycoplasma multi-chaperone network. Our results show that the efficiency of the A. laidlawii multi-chaperone system is driven with the ability of AlIbpA to form both globular and fibrillar structures, thus combining functions of both IbpA and IbpB when transferring the substrate proteins to the HSP70-HSP100 system. In contrast to EcIbpA and EcIbpB, AlIbpA appears as an sHSP, in which the competition between the N- and C-terminal domains regulates the shift of the protein quaternary structure between a fibrillar and globular form, thus representing a molecular mechanism of its functional regulation. While the C-terminus of AlIbpA is responsible for fibrils formation and substrate capture, the N-terminus seems to have a similar function to EcIbpB through facilitating further substrate protein disaggregation using HSP70. Moreover, our results indicate that prior to the final disaggregation process, AlIbpA can directly transfer the substrate to HSP100, thereby representing an alternative mechanism in the HSP interaction network.

Spatiotemporal Patterns of Five Small Heat Shock Protein Genes in Hyphantria cunea in Response to Thermal Stress

Hyphantria cunea (Drury), a destructive polyphagous pest, has been spreading southward after invading northern China, which indicates that this insect species is facing a huge thermal challenge. Small heat shock proteins (sHSPs) function as ATP-independent molecular chaperones that protect insects from heat stress damage. In order to explore the role of sHSPs in the thermotolerance of H. cunea, five novel sHSP genes of H. cunea were cloned, including an orthologous gene (HcHSP21.4) and four species-specific sHSP genes (HcHSP18.9, HcHSP20.1, HcHSP21.5, and HcHSP29.8). Bioinformatics analysis showed that the proteins encoded by these five HcHSPs contained typical α-crystallin domains. Quantitative real-time PCR analysis revealed the ubiquitous expression of all HcHSPs across all developmental stages of H. cunea, with the highest expression levels in pupae and adults. Four species-specific HcHSPs were sensitive to high temperatures. The expression levels of HcHSPs were significantly up-regulated under heat stress and increased with increasing temperature. The expression levels of HcHSPs in eggs exhibited an initial up-regulation in response to a temperature of 40 °C. In other developmental stages, the transcription of HcHSPs was immediately up-regulated at 30 °C or 35 °C. HcHSPs transcripts were abundant in the cuticle before and after heat shock. The expression of HcHSP21.4 showed weak responses to heat stress and constitutive expression in the tissues tested. These results suggest that most of the HcHSPs are involved in high-temperature response and may also have functions in the normal development and reproduction of H. cunea.

Global transcriptome profiling reveals root- and leaf-specific responses of barley (Hordeum vulgare L.) to H2O2

In cereal crops, such as barley (Hordeum vulgare L.), the ability to appropriately respond to environmental cues is an important factor for yield stability and thus for agricultural production. Reactive oxygen species (ROS), such as hydrogen peroxide (H2O2), are key components of signal transduction cascades involved in plant adaptation to changing environmental conditions. H2O2-mediated stress responses include the modulation of expression of stress-responsive genes required to cope with different abiotic and biotic stresses. Despite its importance, knowledge of the effects of H2O2 on the barley transcriptome is still scarce. In this study, we identified global transcriptomic changes induced after application of 10 mM H2O2 to five-day-old barley plants. In total, 1883 and 1001 differentially expressed genes (DEGs) were identified in roots and leaves, respectively. Most of these DEGs were organ-specific, with only 209 DEGs commonly regulated and 37 counter-regulated between both plant parts. A GO term analysis further confirmed that different processes were affected in roots and leaves. It revealed that DEGs in leaves mostly comprised genes associated with hormone signaling, response to H2O2 and abiotic stresses. This includes many transcriptions factors and small heat shock proteins. DEGs in roots mostly comprised genes linked to crucial aspects of H2O2 catabolism and oxidant detoxification, glutathione metabolism, as well as cell wall modulation. These categories include many peroxidases and glutathione transferases. As with leaves, the H2O2 response category in roots contains small heat shock proteins, however, mostly different members of this family were affected and they were all regulated in the opposite direction in the two plant parts. Validation of the expression of the selected commonly regulated DEGs by qRT-PCR was consistent with the RNA-seq data. The data obtained in this study provide an insight into the molecular mechanisms of oxidative stress responses in barley, which might also play a role upon other stresses that induce oxidative bursts.

Influence of temperature variation on gene expression and cocoon production in Bombyx mori Linnaeus, 1758 (Lepidoptera: Bombycidae)

Silkworms (Bombyx mori) are lepidopterans of economic importance for global silk production. However, factors that directly affect the yield and quality of silkworm cocoon production, such as diseases and temperature fluctuations, cause great economic losses. Knowing how they respond to rearing temperature during the most critical stage of their life cycle (i.e., fifth instar) could provide information on their adaptation and improve silk production. In the current work, we analyzed transcriptional data from two groups of B. mori that were reared at 26 °C and 34 °C throughout the fifth instar. The silkworms and cocoons were weighed. In total, 3115 transcripts were differentially expressed (DE; including 1696 down-regulated and 1419 up-regulated) among the 29,157 sequences found by transcriptome assembly. We emphasize the genes associated with immunological response, transcription factors, silk biosynthesis, and heat shock proteins, among the DE transcripts in response to the temperature conditions. Silkworms reared at 34 °C presented a reduced mean body weight (-0.944 g in comparison to the 26 °C group), which had a direct impact on the weight of cocoons formed and the silk conversion rate. These changes were statistically significant when compared to silkworms reared at 26 °C. Mortality rates (6 and 9 %, at 26 °C and 34 °C, respectively) were similar to those obtained in breeding fields. The findings provide information on the biological processes involved in the temperature response mechanism of silkworms, as well as information that may be used in future climatization processes at rearing facilities and in breeding for improved thermotolerance.

Characterization of Hsp17, a Novel Small Heat Shock Protein, in Sphingomonas melonis TY under Heat Stress

Bacteria are constantly exposed to a variety of environmental stresses. Temperature is considered one of the most important environmental factors affecting microbial growth and survival. As ubiquitous environmental microorganisms, Sphingomonas species play essential roles in the biodegradation of organic contaminants, plant protection, and environmental remediation. Understanding the mechanism by which they respond to heat shock will help further improve cell resistance by applying synthetic biological strategies. Here, we assessed the transcriptomic and proteomic responses of Sphingomonas melonis TY to heat shock and found that stressful conditions caused significant changes in functional genes related to protein synthesis at the transcriptional level. The most notable changes observed were increases in the transcription (1,857-fold) and protein expression (11-fold) of Hsp17, which belongs to the small heat shock protein family, and the function of Hsp17 in heat stress was further investigated in this study. We found that the deletion of hsp17 reduced the capacity of the cells to tolerate high temperatures, whereas the overexpression of hsp17 significantly enhanced the ability of the cells to withstand high temperatures. Moreover, the heterologous expression of hsp17 in Escherichia coli DH5α conferred to the bacterium the ability to resist heat stress. Interestingly, its cells were elongated and formed connected cells following the increase in temperature, while hsp17 overexpression restored their normal morphology under high temperature. In general, these results indicate that the novel small heat shock protein Hsp17 greatly contributes to maintaining cell viability and morphology under stress conditions. IMPORTANCE Temperature is generally considered the most important factor affecting metabolic functions and the survival of microbes. As molecular chaperones, small heat shock proteins can prevent damaged protein aggregation during abiotic stress, especially heat stress. Sphingomonas species are widely distributed in nature, and they can frequently be found in various extreme environments. However, the role of small heat shock proteins in Sphingomonas under high-temperature stress has not been elucidated. This study greatly enhances our understanding of a novel identified protein, Hsp17, in S. melonis TY in terms of its ability to resist heat stress and maintain cell morphology under high temperature, leading to a broader understanding of how microbes adapt to environmental extremes. Furthermore, our study will provide potential heat resistance elements for further enhancing cellular resistance as well as the synthetic biological applications of Sphingomonas.

The HSPB1-p62/SQSTM1 functional complex regulates the unconventional secretion and transcellular spreading of the HD-associated mutant huntingtin protein

Conformational diseases, such as Alzheimer, Parkinson and Huntington diseases, are part of a common class of neurological disorders characterized by the aggregation and progressive accumulation of proteins bearing aberrant conformations. Huntington disease (HD) has autosomal dominant inheritance and is caused by mutations leading to an abnormal expansion in the polyglutamine (polyQ) tract of the huntingtin (HTT) protein, leading to the formation of HTT inclusion bodies in neurons of affected patients. Interestingly, recent experimental evidence is challenging the conventional view by which the disease pathogenesis is solely a consequence of the intracellular accumulation of mutant protein aggregates. These studies reveal that transcellular transfer of mutated huntingtin protein is able to seed oligomers involving even the wild-type (WT) forms of the protein. To date, there is still no successful strategy to treat HD. Here, we describe a novel functional role for the HSPB1-p62/SQSTM1 complex, which acts as a cargo loading platform, allowing the unconventional secretion of mutant HTT by extracellular vesicles. HSPB1 interacts preferentially with polyQ-expanded HTT compared with the WT protein and affects its aggregation. Furthermore, HSPB1 levels correlate with the rate of mutant HTT secretion, which is controlled by the activity of the PI3K/AKT/mTOR signalling pathway. Finally, we show that these HTT-containing vesicular structures are biologically active and able to be internalized by recipient cells, therefore providing an additional mechanism to explain the prion-like spreading properties of mutant HTT. These findings might also have implications for the turn-over of other disease-associated, aggregation-prone proteins.

A new kid in the folding funnel: Molecular chaperone activities of the BRICHOS domain

The BRICHOS protein superfamily is a diverse group of proteins associated with a wide variety of human diseases, including respiratory distress, COVID-19, dementia, and cancer. A key characteristic of these proteins-besides their BRICHOS domain present in the ER lumen/extracellular part-is that they harbor an aggregation-prone region, which the BRICHOS domain is proposed to chaperone during biosynthesis. All so far studied BRICHOS domains modulate the aggregation pathway of various amyloid-forming substrates, but not all of them can keep denaturing proteins in a folding-competent state, in a similar manner as small heat shock proteins. Current evidence suggests that the ability to interfere with the aggregation pathways of substrates with entirely different end-point structures is dictated by BRICHOS quaternary structure as well as specific surface motifs. This review aims to provide an overview of the BRICHOS protein family and a perspective of the diverse molecular chaperone-like functions of various BRICHOS domains in relation to their structure and conformational plasticity. Furthermore, we speculate about the physiological implication of the diverse molecular chaperone functions and discuss the possibility to use the BRICHOS domain as a blood-brain barrier permeable molecular chaperone treatment of protein aggregation disorders.

Structures of Get3d reveal a distinct architecture associated with the emergence of photosynthesis

Homologs of the protein Get3 have been identified in all domains yet remain to be fully characterized. In the eukaryotic cytoplasm, Get3 delivers tail-anchored (TA) integral membrane proteins, defined by a single transmembrane helix at their C terminus, to the endoplasmic reticulum. While most eukaryotes have a single Get3 gene, plants are notable for having multiple Get3 paralogs. Get3d is conserved across land plants and photosynthetic bacteria and includes a distinctive C-terminal α-crystallin domain. After tracing the evolutionary origin of Get3d, we solve the Arabidopsis thaliana Get3d crystal structure, identify its localization to the chloroplast, and provide evidence for a role in TA protein binding. The structure is identical to that of a cyanobacterial Get3 homolog, which is further refined here. Distinct features of Get3d include an incomplete active site, a "closed" conformation in the apo-state, and a hydrophobic chamber. Both homologs have ATPase activity and are capable of binding TA proteins, supporting a potential role in TA protein targeting. Get3d is first found with the development of photosynthesis and conserved across 1.2 billion years into the chloroplasts of higher plants across the evolution of photosynthesis suggesting a role in the homeostasis of photosynthetic machinery.

Protein Aggregates and Aggrephagy in Myopathies

A number of muscular disorders are hallmarked by the aggregation of misfolded proteins within muscle fibers. A specialized form of macroautophagy, termed aggrephagy, is designated to remove and degrade protein aggregates. This review aims to summarize what has been studied so far about the direct involvement of aggrephagy and the activation of the key players, among others, p62, NBR1, Alfy, Tollip, Optineurin, TAX1BP1 and CCT2 in muscular diseases. In the first part of the review, we describe the aggrephagy pathway with the involved proteins; then, we illustrate the muscular disorder histologically characterized by protein aggregates, highlighting the role of aggrephagy pathway abnormalities in these muscular disorders.

Rice OsHsp16.9A interacts with OsHsp101 to confer thermotolerance

Class I small heat shock proteins (CI sHSPs), OsHsp16.9A and OsHsp18.0, share 74% identity in amino acid sequences and accumulate in response to heat shock treatments. Individual rice transformants overexpressing OsHsp16.9A and OsHsp18.0 exhibit distinct thermoprotection/thermotolerance modes. Under high temperature stress, OsHsp16.9A-overexpressing lines showed higher seed germination rate, seedling survival, and pollen germination than wild-type controls, while OsHsp18.0 overexpression provided higher thermoprotection/thermotolerance for seedling survival. To elucidate the functional roles of OsHsp16.9A, mass spectrometry was used to identify OsHsp16.9A-interacting proteins. OsHsp101 was consistently identified in the OsHsp16.9A protein complex in several mass spectrometry analyses of seed proteins from OsHsp16.9A-overexpressing lines. Both OsHsp16.9A and OsHsp101 proteins accumulated during similar developmental stages of rice seeds and formed a heat-stable complex under high temperature treatments in in vitro assays. Co-localization of OsHsp16.9A and OsHsp101 was observed via ratiometric bimolecular fluorescence complementation analyses. Amino acid mutation studies revealed that OsHsp16.9A glutamate residue 74 and amino acid residues 23-36 were essential for OsHsp16.9A-OsHsp101 interaction. Moreover, overexpressing OsHsp16.9A in OsHsp101 knockdown mutants did not increase the seed germination rate under heat stress, which further confirmed the functional roles of OsHsp16.9A-OsHsp101 interaction in conferring thermotolerance to rice plants.

AccsHSP21.7 enhances the antioxidant capacity of Apis cerana cerana

BACKGROUND

The widespread use of glyphosate has many adverse effects on Apis cerana cerana. Due to the incomplete understanding of the molecular mechanisms of glyphosate toxicity, there are no available methods for mitigating the threat of glyphosate to Apis cerana cerana. Small heat shock proteins (sHSPs) play an important role in resisting oxidative stress, but their mechanism of action in Apis cerana cerana remains unclear.

RESULTS

In this experiment, we cloned and identified AccsHSP21.7. Studies have shown that AccsHSP21.7 contains binding motifs for various transcription factors related to oxidative stress. Abiotic stresses induced the expression of AccsHSP21.7. Bacteriostatic testing of a recombinant AccsHSP21.7 protein proved that Escherichia coli overexpressing AccsHSP21.7 showed increased resistance to oxidative stress. Knocking down the AccsHSP21.7 gene caused significant damage to midgut cells, which seriously disrupted the antioxidant system in Apis cerana cerana and greatly increased mortality under glyphosate stress.

CONCLUSION

This study investigated the relationship between antioxidant regulation and the AccsHSP21.7 gene at the molecular level, and the results have guiding significance for the improvement of stress resistance in Apis cerana cerana. © 2023 Society of Chemical Industry.

Expression of the gonad-specific small heat shock protein, CfHSP20.2, in the spruce budworm, Choristoneura fumiferana (Clem.)

Small heat shock proteins (sHSPs) play important roles in insect development and stress resistance. However, the in vivo functions and mechanisms of action remain largely unknown or unclear for most members of the sHSPs in insects. This study investigated the expression of CfHSP20.2 in the spruce budworm, Choristoneura fumiferana (Clem.) under normal and heat-stress conditions. Under normal conditions, CfHSP20.2 transcript and protein were highly and constantly expressed in the testes of male larvae, pupae and young adults and in the ovaries of female late-stage pupae and adults. After adult eclosion, CfHSP20.2 remained highly and almost constantly expressed in the ovaries, but in contrast, was downregulated in the testes. Upon heat stress, CfHSP20.2 was upregulated in the gonads and non-gonadal tissues in both sexes. These results indicate that CfHSP20.2 expression is gonad-specific and heat-inducible. This provides evidence that the CfHSP20.2 protein plays important roles during reproductive development under normal environmental conditions, while under heat-stress conditions, it may also enhance the thermal tolerance of the gonads and non-gonadal tissues.

Protein Changes in Shade and Sun Haberlea rhodopensis Leaves during Dehydration at Optimal and Low Temperatures

Haberlea rhodopensis is a unique resurrection plant of high phenotypic plasticity, colonizing both shady habitats and sun-exposed rock clefts. H. rhodopensis also survives freezing winter temperatures in temperate climates. Although survival in conditions of desiccation and survival in conditions of frost share high morphological and physiological similarities, proteomic changes lying behind these mechanisms are hardly studied. Thus, we aimed to reveal ecotype-level and temperature-dependent variations in the protective mechanisms by applying both targeted and untargeted proteomic approaches. Drought-induced desiccation enhanced superoxide dismutase (SOD) activity, but FeSOD and Cu/ZnSOD-III were significantly better triggered in sun plants. Desiccation resulted in the accumulation of enzymes involved in carbohydrate/phenylpropanoid metabolism (enolase, triosephosphate isomerase, UDP-D-apiose/UDP-D-xylose synthase 2, 81E8-like cytochrome P450 monooxygenase) and protective proteins such as vicinal oxygen chelate metalloenzyme superfamily and early light-induced proteins, dehydrins, and small heat shock proteins, the latter two typically being found in the latest phases of dehydration and being more pronounced in sun plants. Although low temperature and drought stress-induced desiccation trigger similar responses, the natural variation of these responses in shade and sun plants calls for attention to the pre-conditioning/priming effects that have high importance both in the desiccation responses and successful stress recovery.

Differential Accumulation of sHSPs Isoforms during Desiccation of the Resurrection Plant Haberlea rhodopensis Friv. under Optimal and High Temperature

Haberlea rhodopensis belongs to the small group of angiosperms that can survive desiccation to air-dry state and quickly restore their metabolism upon rehydration. In the present study, we investigated the accumulation of sHSPs and the extent of non-photochemical quenching during the downregulation of photosynthesis in H. rhodopensis leaves under desiccation at optimum (23 °C) and high temperature (38 °C). Desiccation of plants at 38 °C caused a stronger reduction in photosynthetic activity and corresponding enhancement in thermal energy dissipation. The accumulation of sHSPs was investigated by Western blot. While no expression of sHPSs was detected in the unstressed control sample, exposure of well-hydrated plants to high temperature induced an accumulation of sHSPs. Only a faint signal was observed at 50% RWC when dehydration was applied at 23 °C. Several cross-reacting polypeptide bands in the range of 16.5-19 kDa were observed in plants desiccated at high temperature. Two-dimensional electrophoresis and immunoblotting revealed the presence of several sHSPs with close molecular masses and pIs in the range of 5-8.0 that differed for each stage of treatment. At the latest stages of desiccation, fourteen different sHSPs could be distinguished, indicating that sHSPs might play a crucial role in H. rhodopensis under dehydration at high temperatures.

Characterizing the sarcoplasmic proteome of aged pork chops classified by purge loss

Unpredictable variation in quality, including fresh pork water-holding capacity, remains challenging to pork processors and customers. Defining the diverse factors that influence fresh pork water-holding capacity is necessary to make progress in refining pork quality prediction methods. The objective was to utilize liquid chromatography and mass spectrometry coupled with tandem mass tag (TMT) multiplexing to evaluate the sarcoplasmic proteome of aged pork loins classified by purge loss. Fresh commercial pork loins were collected, aged 12 or 14 d postmortem, and pork quality and sensory attributes were evaluated. Chops were classified into Low (N = 27, average purge = 0.33%), Intermediate (N = 27, average purge = 0.72%), or High (N = 27, average purge = 1.19%) chop purge groups. Proteins soluble in a low-ionic strength buffer were extracted, digested with trypsin, labeled with 11-plex isobaric TMT reagents, and detected using a Q-Exactive Mass Spectrometer. Between the Low and High purge groups, 40 proteins were differentially (P < 0.05) abundant. The Low purge group had a greater abundance of proteins classified as structural and contractile, sarcoplasmic reticulum and calcium regulating, chaperone, and citric acid cycle enzymes than the High purge group. The presence of myofibrillar proteins in the aged sarcoplasmic proteome is likely due to postmortem degradation. These observations support our hypothesis that pork chops with low purge have a greater abundance of structural proteins in the soluble protein fraction. Together, these and other proteins in the aged sarcoplasmic proteome may be biomarkers of pork water-holding capacity. Additional research should establish the utility of these proteins as biomarkers early postmortem and over subsequent aging periods.

Is the lipochaperone activity of sHSP a key to the stress response encoded in its primary sequence?

Several strategies have been put in place by organisms to adapt to their environment. One of these strategies is the production of stress proteins such as sHSPs, which have been widely described over the last 30 years for their role as molecular chaperones. Some sHSPs have, in addition, the particularity to exert a lipochaperone role by interacting with membrane lipids to maintain an optimal membrane fluidity. However, the mechanisms involved in this sHSP-lipid interaction remain poorly understood and described rather sporadically in the literature. This review gathers the information concerning the structure and function of these proteins available in the literature in order to highlight the mechanism involved in this interaction. In addition, analysis of primary sequence data of sHSPs available in database shows that sHSPs can interact with lipids via certain amino acid residues present on some β sheets of these proteins. These residues could have a key role in the structure and/or oligomerization dynamics of sHPSs, which is certainly essential for interaction with membrane lipids and consequently for maintaining optimal cell membrane fluidity.

The Common Bean Small Heat Shock Protein Nodulin 22 from Phaseolus vulgaris L. Assembles into Functional High-Molecular-Weight Oligomers

Small heat shock proteins (sHsps) are present in all domains of life. These proteins are responsible for binding unfolded proteins to prevent their aggregation. sHsps form dynamic oligomers of different sizes and constitute transient reservoirs for folding competent proteins that are subsequently refolded by ATP-dependent chaperone systems. In plants, the sHsp family is rather diverse and has been associated with the ability of plants to survive diverse environmental stresses. Nodulin 22 (PvNod22) is an sHsp of the common bean (Phaseolus vulgaris L.) located in the endoplasmic reticulum. This protein is expressed in response to stress (heat or oxidative) or in plant roots during mycorrhizal and rhizobial symbiosis. In this work, we study its oligomeric state using a combination of in silico and experimental approaches. We found that recombinant PvNod22 was able to protect a target protein from heat unfolding in vitro. We also demonstrated that PvNod22 assembles into high-molecular-weight oligomers with diameters of ~15 nm under stress-free conditions. These oligomers can cluster together to form high-weight polydisperse agglomerates with temperature-dependent interactions; in contrast, the oligomers are stable regarding temperature.

Effects of Molecular Crowding and Betaine on HSPB5 Interactions, with Target Proteins Differing in the Quaternary Structure and Aggregation Mechanism

The aggregation of intracellular proteins may be enhanced under stress. The expression of heat-shock proteins (HSPs) and the accumulation of osmolytes are among the cellular protective mechanisms in these conditions. In addition, one should remember that the cell environment is highly crowded. The antiaggregation activity of HSPB5 and the effect on it of either a crowding agent (polyethylene glycol (PEG)) or an osmolyte (betaine), or their mixture, were tested on the aggregation of two target proteins that differ in the order of aggregation with respect to the protein: thermal aggregation of glutamate dehydrogenase and DTT-induced aggregation of lysozyme. The kinetic analysis of the dynamic light-scattering data indicates that crowding can decrease the chaperone-like activity of HSPB5. Nonetheless, the analytical ultracentrifugation shows the protective effect of HSPB5, which retains protein aggregates in a soluble state. Overall, various additives may either improve or impair the antiaggregation activity of HSPB5 against different protein targets. The mixed crowding arising from the presence of PEG and 1 M betaine demonstrates an extraordinary effect on the oligomeric state of protein aggregates. The shift in the equilibrium of HSPB5 dynamic ensembles allows for the regulation of its antiaggregation activity. Crowding can modulate HSPB5 activity by affecting protein-protein interactions.

Targeting small heat shock proteins to degrade aggregates as a potential strategy in neurodegenerative diseases

Neurodegenerative diseases (NDs) are aging-related diseases that involve the death of neurons in the brain. Dysregulation of protein homeostasis leads to the production of toxic proteins or the formation of aggregates, which is the pathological basis of NDs. Small heat shock proteins (HSPB) is involved in the establishment of a protein quality control (PQC) system to maintain cellular homeostasis. HSPB can be secreted into the extracellular space and delivered by various routes, especially extracellular vehicles (EVs). HSPB plays an important role in influencing the aggregation phase of toxic proteins involved in heat shock transcription factor (HSF) regulation, oxidative stress, autophagy and apoptosis pathways. HSPB conferred neuroprotective effects by resisting toxic protein aggregation, reducing autophagy and reducing neuronal apoptosis. The HSPB treatment strategies, including targeted PQC system therapy and delivery of EVs-HSPB, can improve disease manifestations for NDs. This review aims to provide a comprehensive insight into the impact of HSPB in NDs and the feasibility of new technology to enhance HSPB expression and EVs-HSPB delivery for neurodegenerative disease.

The permanently chaperone-active small heat shock protein Hsp17 from Caenorhabditis elegans exhibits topological separation of its N-terminal regions

Small Heat shock proteins (sHsps) are a family of molecular chaperones that bind nonnative proteins in an ATP-independent manner. Caenorhabditis elegans encodes 16 different sHsps, among them Hsp17, which is evolutionarily distinct from other sHsps in the nematode. The structure and mechanism of Hsp17 and how these may differ from other sHsps remain unclear. Here, we find that Hsp17 has a distinct expression pattern, structural organization, and chaperone function. Consistent with its presence under nonstress conditions, and in contrast to many other sHsps, we determined that Hsp17 is a mono-disperse, permanently active chaperone in vitro, which interacts with hundreds of different C. elegans proteins under physiological conditions. Additionally, our cryo-EM structure of Hsp17 reveals that in the 24-mer complex, 12 N-terminal regions are involved in its chaperone function. These flexible regions are located on the outside of the spherical oligomer, whereas the other 12 N-terminal regions are engaged in stabilizing interactions in its interior. This allows the same region in Hsp17 to perform different functions depending on the topological context. Taken together, our results reveal structural and functional features that further define the structural basis of permanently active sHsps.

Antioxidant and anti-inflammatory activities of Centratherum anthelminticum (L.) Kuntze seed oil in diabetic nephropathy via modulation of Nrf-2/HO-1 and NF-κB pathway

Background

Type 2 diabetes mellitus (T2DM) approximately constitutes 90% of the reported cases. 30-40% of diabetics eventually develop diabetic nephropathy (DN); accounting for one of the major causes of morbidity and mortality. Increased glucose autoxidation and non-enzymatic glycation of proteins in diabetic kidneys lead to the excessive generation of reactive oxygen species (ROS) that results in lipid peroxidation and activation of inflammatory mediators which overwhelms the scavenging capacity of the antioxidant defense system (Nrf2/Keap1/HO-1). Centratherum anthelminticum commonly called as kali zeeri (bitter cumin) and its seeds are well known for culinary purposes in Asia (Pakistan). It has reported anti-inflammatory, antioxidant, and anti-diabetic activities. The present study has attempted to explore the in-vivo anti-inflammatory, antioxidant and antihyperglycemic potential of the C. anthelminticum seed’s fixed oil (FO) and its fractions in high fat-high fructose-streptozotocin (HF-HFr-STZ) induced T2DM rat model.

Methods

The T2DM rat model was developed by giving a high-fat and high-fructose diet followed by a single intraperitoneal injection of streptozotocin (STZ 60 mg/kg) on 28th day of the trial. After 72 hours of this injection, rats showing fasting blood glucose (FBG) levels≥230 mg/dL were recruited into six groups. These groups were orally administered distilled water (1 mL/kg), Gliclazide (200 mg/kg), Centratherum anthelminticum seed (FO) and its hexane (HF), chloroform (CF) and ethanol (EF) soluble fractions (200 mg/kg each), respectively for 4 weeks (i.e. 28 days). Blood, serum, and kidney tissue samples of euthanized animals were used for biochemical, pro-inflammatory, and antioxidant markers (ELISA, qRT-PCR, and spectrophotometric assays) and histology, respectively.

Results

C. anthelminticum FO and its fractions reduced the lipid peroxidation, and improved the antioxidant parameters: enzymatic (SOD, CAT, and GPx), non-enzymatic (GSH), and mRNA expression of anti-inflammatory markers (Nrf-2, keap1, and HO-1). mRNA expression of inflammatory and apoptotic markers (TNF-α, IL-1β, COX-1, NF-κB, Bax, and Bcl-2) were attenuated along with improved kidney architecture.

Conclusion

C. anthelminticum can mitigate inflammation and oxidative stress in early DN. The anti-nephropathic effect can be attributed to its ability to down-regulate NF-κB and by bringing the Nrf-2 expression levels to near normal.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12906-022-03776-x.

Identification of Six Small Heat Shock Protein Genes in Ostrinia furnacalis (Lepidoptera: Pyralidae) and Analysis of Their Expression Patterns in Response to Environmental Stressors

Ostrinia furnacalis (Guenée) is a major insect pest in maize production that is highly adaptable to the environment. Small heat shock proteins (sHsps) are a class of chaperone proteins that play an important role in insect responses to various environmental stresses. The present study aimed to clarify the responses of six O. furnacalis sHsps to environmental stressors. In particular, we cloned six sHsp genes, namely, OfHsp24.2, OfHsp21.3, OfHsp20.7, OfHsp21.8, OfHsp29.7, and OfHsp19.9, from O. furnacalis. The putative proteins encoded by these genes contained a typical α-crystallin domain. Real-time quantitative polymerase chain reaction was used to analyze the differences in the expression of these genes at different developmental stages, in different tissues of male and female adults, and in O. furnacalis under UV-A and extreme temperature stresses. The six OfsHsp genes were expressed at significantly different levels based on the developmental stage and tissue type in male and female adults. Furthermore, all OfsHsp genes were significantly upregulated in both male and female adults under extreme temperature and UV-A stresses. Thus, O. furnacalis OfsHsp genes play important and unique regulatory roles in the developmental stages of the insect and in response to various environmental stressors.

Three Heat Shock Protein Genes and Antioxidant Enzymes Protect Pardosa pseudoannulata (Araneae: Lycosidae) from High Temperature Stress

Pardosa pseudoannulata (P. pseudoannulata) is an essential natural predatory enemy in rice ecosystems. The fluctuating climate may cause them to experience heat stress, whereas heat shock proteins (HSPs) and antioxidant enzymes help resist heat damage. Herein, we cloned and characterized the full-length genes PpHSP27, PpHSP60, and PpHSC70 from P. pseudoannulata. Changes in gene expression levels and superoxide dismutase (SOD), catalase (CAT), and glutathione transferase (GST) activities in adult male and female P. pseudoannulata were measured at different stress exposure times and temperatures. We found that the abovementioned HSP genes belong to the sHSP, HSP60, and HSP70 families. The expression of the three HSP genes and the activities of SOD, CAT, and GST were significantly upregulated with the increasing stress temperature and time. The knockdown of the three HSP genes via RNA interference significantly decreased the survival rate of male and female P. pseudoannulata during high temperature stress. Thus, PpHSP27, PpHSP60, and PpHSC70 play an important role in the heat tolerance of P. pseudoannulata, and SOD, CAT, and GST enable recovery heat stress-induced oxidative damage. Their changes and regulation during high temperature stress can improve spiders' adaptability in the field and enhance the biological control of environmental pests.

Coping with global warming: Adult thermal thresholds in four pestiferous Anastrepha species determined under experimental laboratory conditions and development/survival times of immatures and adults under natural field conditions

Climate change, particularly global warming, is disturbing biological processes in unexpected ways and forcing us to re-study/reanalyze the effects of varying temperatures, among them extreme ones, on insect functional traits such as lifespan and fecundity/fertility. Here we experimentally tested, under both laboratory and field conditions, the effects of an extreme range of temperatures (5, 10, 15, 20, 30, 40, and 45 °C, and the naturally varying conditions experienced in the field), on survivorship/lifespan, fecundity, and fertility of four pestiferous fruit fly species exhibiting contrasting life histories and belonging to two phylogenetic groups within the genus Anastrepha: A. ludens, A. obliqua, A. striata, and A. serpentina. In the field, we also measured the length of the entire life cycle (egg to adult), and in one species (A. ludens), the effect on the latter of the host plant (mango and grapefruit). Under laboratory conditions, none of the adults, independent of species, could survive a single day when exposed to a constant temperature of 45 °C, but A. striata and A. serpentina females/males survived at the highly contrasting temperatures of 5 and 40 °C at least 7 days. Maximum longevity was achieved in all species at 15 °C (375, 225, 175 and 160 days in A. ludens, A. serpentina, A. striata and A. obliqua females, respectively). Anastrepha ludens layed many eggs until late in life (368 days) at 15 °C, but none eclosed. Eclosion was only observed in all species at 20 and 30 °C. Under natural conditions, flies lived ca. 100 days less than in the laboratory at 15 °C, likely due to the physiological cost of dealing with the highly varying environmental patterns over 24 h (minimum and maximum temperatures and relative humidity of ca. 10–40 °C, and 22–100%, respectively). In the case of A. ludens, the immature’s developmental time was shorter in mango, but adult survival was longer than in grapefruit. We discuss our results considering the physiological processes regulating the traits measured and tie them to the increasing problem of global warming and its hidden effects on the physiology of insects, as well as the ecological and pest management implications.