Characterization of the groEL-like genes in Streptomyces albus.

Three GroEL-like heat shock proteins (HSP56, HSP58, and HSP18) have been observed in Streptomyces albus (G. Guglielmi, P. Mazodier, C. J. Thompson, and J. Davies, J. Bacteriol. 173:7374-7381, 1991). Here we report the cloning and complete nucleotide sequence of groEL1, which encodes HSP18 and HSP58, and groEL2, which encodes HSP56. Both nucleotide sequences predicted proteins of 56,680 Da that were 70% identical. The 5' nucleotide sequence of groEL1 coded for a protein corresponding to HSP18 that may be a processed gene product. At least two groEL-like genes were present in all 12 Streptomyces species tested; they were not closely linked in the genome. groEL1, but not groEL2, was adjacent to a groES-like gene.     

Population variability in heat shock proteins among three Antarctic penguin species

Heat shock proteins (HSPs) are synthesised under stressful conditions such as exposure to elevated temperatures, contamination, free radicals, UV light or pathophysiological states resulting from parasites and/or pathogens. HSPs function to protect cells by means of modulation of protein folding. In Antarctica, these proteins have been studied in such organisms as protozoa and fishes, without attention to geographical variation. We studied the variation of HSP70 and HSP60 levels in Gentoo, Adelie and Chinstrap penguins among different populations along the Antarctic Peninsula from King George Island (62°15′S) to Avian Island (67°46′S). Our results show that the northern population of Gentoo penguin showed higher levels of HSP70 and HSP60 than the southern population. High temperature, human impact and immunity as a proxy for parasites and diseases in northern locations could explain such variation. Adelie penguin only showed significant geographical variation in HSP70, increasing north to south, a pattern perhaps related to increased UV radiation and decreased temperatures from north to south. Chinstrap penguin shows no population differences in the variation in neither HSP70 nor HSP60, although HSP70 showed marginally significant differences. Sexual differences in the level of these proteins are also discussed.     

Cloning and expression of heat shock protein genes in two whitefly species in response to thermal stress

Two whitefly species, Trialeurodes vaporariorum and Bemisia tabaci biotype B were shown to have different temperature tolerance and seasonal dynamics. To determine whether this variation in thermal tolerance is related to different expression patterns of heat shock protein (hsp) genes during temperature stress, we obtained complete cDNA sequences for hsp90, hsp70 and hsp20, and analysed their expression profiles across temperature gradients by real‐time quantitative polymerase chain reaction (PCR). Six full‐length cDNAs were cloned and sequenced from these two species. The full‐length cDNAs of hsp90s contain 2166 and 2157 bp open‐reading frames (ORF) which encode proteins with calculated molecular weights of 83 013 and 82 857 Da in T. vaporariorum and B. tabaci, respectively. The 1947 and 1959 bp ORFs of whitefly hsp70s comprise 649 and 653 amino acids with the calculated masses of 70 885 and 71 008 Da in T. vaporariorum and B. tabaci, respectively. Both complete cDNAs of hsp20 of T. vaporariorum and B. tabaci contain 585 bp ORFs and deduced amino acid sequences had molecular weights of 21 559 and 21 539 Da, respectively. The hsp expression profile results showed that temperatures for onset (T_on) or maximal (T_max) induction of hsp expression in T. vaporariorum were generally 2–6°C lower than those in B. tabaci. These results suggest that the T_on (or T_max) of hsps can represent the differences in temperature tolerance of these two whitefly species, and may be used to determine their natural geographical distribution and natural population seasonal dynamics. Significant upregulation of most hsps were observed when temperature stress was lifted, except that hsp70 and hsp20 of B. tabaci did not respond to the cold stress, indicating that response to heat and cold stress may have a different genetic and physiological basis in two whitefly species. These results highlight the importance of understanding the complexity of the heat shock response across multiple isoforms while attempting to link them to whole‐organism traits such as thermal tolerance.     

The evolution of heat shock genes and expression patterns of heat shock proteins in the species from temperature contrasting habitats

Heat shock genes are the most evolutionarily ancient among the systems responsible for adaptation of organisms to a harsh environment. The encoded proteins (heat shock proteins, Hsps) represent the most important factors of adaptation to adverse environmental conditions. They serve as molecular chaperones, providing protein folding and preventing aggregation of damaged cellular proteins. Structural analysis of the heat shock genes in individuals from both phylogenetically close and very distant taxa made it possible to reveal the basic trends of the heat shock gene organization in the context of adaptation to extreme conditions. Using different model objects and nonmodel species from natural populations, it was demonstrated that modulation of the Hsps expression during adaptation to different environmental conditions could be achieved by changing the number and structural organization of heat shock genes in the genome, as well as the structure of their promoters. It was demonstrated that thermotolerant species were usually characterized by elevated levels of Hsps under normal temperature or by the increase in the synthesis of these proteins in response to heat shock. Analysis of the heat shock genes in phylogenetically distant organisms is of great interest because, on one hand, it contributes to the understanding of the molecular mechanisms of evolution of adaptogenes and, on the other hand, sheds the light on the role of different Hsps families in the development of thermotolerance and the resistance to other stress factors.     

Antibodies to two major chicken heat shock proteins cross-react with similar proteins in widely divergent species.

Three of the proteins induced by heat shock of chicken embryo fibroblasts have been purified, and rabbit antibodies have been raised against them. These antibodies have been used in radioimmune precipitation reactions and in a solid-phase immune assay to detect antigenic material in non-heat-shocked chicken tissues and in extracts of widely different species ranging from yeast to mammalian tissue culture cells and human erythrocyte ghosts. Antibodies to two of the major chicken heat shock proteins, chsp89 and chsp70, cross-reacted with proteins of similar molecular weights in normal embryonic and adult chicken tissues and in extracts from widely different organisms. These data provide further evidence for the university of the heat shock response and conservation of proteins induced by this type of stress.     

Genotype-specific heat shock proteins in two maize inbreds

Summary Leaf blade tissue of maize inbred lines B73 and Mo17 was analyzed for intraspecific genetic variability in the heat shock response. The maize inbreds were characterized for acquired thermal tolerance and patterns of heat shock protein synthesis. The leakage conductivity assay of membrane stability during stress indicated that Mol7 possesses greater potential than B73 to acquire thermal tolerance. Poly(A)⁺ RNA, extracted from leaf blades, was translated in vitro in the presence of ³⁵S-methionine and the translation products separated by twodimensional gel electrophoresis. Major genotypic differences were observed in the translation products. Mo 17 synthesized twelve unique heat shock proteins in the 15–18 kD range, but B73 synthesized only three unique heat shock proteins in the same range. DNA polymorphisms were observed between the maize lines using ³²P labeled heat shock protein gene probes.Abbreviations HKT Heat-killing time - HS Heat shock - HSP Heat shock protein - HMW High molecular weight - LMW Low molecular weight Contribution of the College of Agricultural Sciences, Texas Tech University, Journal No. T-4-333     

A primary survey on bryophyte species reveals two novel classes of nucleotide-binding site (NBS) genes

Due to their potential roles in pathogen defense, genes encoding nucleotide-binding site (NBS) domain have been particularly surveyed in many angiosperm genomes. Two typical classes were found: one is the TIR-NBS-LRR (TNL) class and the other is the CC-NBS-LRR (CNL) class. It is seldom known, however, what kind of NBS-encoding genes are mainly present in other plant groups, especially the most ancient groups of land plants, that is, bryophytes. To fill this gap of knowledge, in this study, we mainly focused on two bryophyte species: the moss Physcomitrella patens and the liverwort Marchantia polymorpha, to survey their NBS-encoding genes. Surprisingly, two novel classes of NBS-encoding genes were discovered. The first novel class is identified from the P. patens genome and a typical member of this class has a protein kinase (PK) domain at the N-terminus and a LRR domain at the C-terminus, forming a complete structure of PK-NBS-LRR (PNL), reminiscent of TNL and CNL classes in angiosperms. The second class is found from the liverwort genome and a typical member of this class possesses an α/β-hydrolase domain at the N-terminus and also a LRR domain at the C-terminus (Hydrolase-NBS-LRR, HNL). Analysis on intron positions and phases also confirmed the novelty of HNL and PNL classes, as reflected by their specific intron locations or phase characteristics. Phylogenetic analysis covering all four classes of NBS-encoding genes revealed a closer relationship among the HNL, PNL and TNL classes, suggesting the CNL class having a more divergent status from the others. The presence of specific introns highlights the chimerical structures of HNL, PNL and TNL genes, and implies their possible origin via exon-shuffling during the quick lineage separation processes of early land plants.     

Acquired thermotolerance and heat shock proteins in thermophiles from the three phylogenetic domains.

Thermophilic organisms from each of the three phylogenetic domains (Bacteria, Archaea, and Eucarya) acquired thermotolerance after heat shock. Bacillus caldolyticus grown at 60 degrees C and heat shocked at 69 degrees C for 10 min showed thermotolerance at 74 degrees C, Sulfolobus shibatae grown at 70 degrees C and heat shocked at 88 degrees C for 60 min showed thermotolerance at 95 degrees C, and Thermomyces lanuginosus grown at 50 degrees C and heat shocked at 55 degrees C for 60 min showed thermotolerance at 58 degrees C. Determinations of protein synthesis during heat shock revealed differences in the dominant heat shock proteins for each species. For B. caldolyticus, a 70-kDa protein dominated while for S. shibatae, a 55-kDa protein dominated and for T. lanuginosus, 31- to 33-kDa proteins dominated. Reagents that disrupted normal protein synthesis during heat shock prevented the enhanced thermotolerance.     

Proteomics analysis of two heat shock proteins in insects

Heat shock proteins (HSPs) are found in all living organisms, from bacteria to humans, are expressed under stress. In this study, characterization of two families of HSP including HSP60 and HSP70 protein was compared in different insect species from different orders. According to the conserved motifs analysis, none of the motifs were shared by all insects of two protein families but each family had their own common motifs. Functional and structural analyses were carried out on seven different insect species from each protein family as the representative samples. These analyses were performed via ExPASy database tools. The tertiary structure of Drosophila melanogater as the sample of each protein family were predicted by the Phyre2 and TM-score servers then their qualities were verified by SuperPose and PROCHECK. The tertiary structures were predicted through the “c4pj1E” model (PDB Accession Code: 4pj1) in HSP60 family and “c3d2fC” model (PDB Accession Code: 3d2f) in HSP70 family. The protein phylogenetic tree was constructed using the Neighbor-joining (NJ) method by Molecular Evolutionary Genetic Analysis (MEGA) 6.06. According to the results, there was a high identity of HSP60 and HSP70 families so that they should be derived from a common ancestor however they belonged to separate groups. In protein–protein interaction analysis by STRING 10.0, 10 common enriched pathways of biological process, molecular function and Kyoto Encyclopedia of Genes and Genomes (KEGG) were identified in D. melanogaster in both families. The obtained data provide a background for bioinformatic studies of the function and evolution of insects and other organisms.

Communicated by Ramaswamy H. Sarma     

Comparative analysis of the small heat shock proteins in three angiosperm genomes identifies new subfamilies and reveals diverse evolutionary patterns

The small heat shock proteins (sHSPs) are a diverse family of molecular chaperones. It is well established that these proteins are crucial components of the plant heat shock response. They also have important roles in other stress responses and in normal development. We have conducted a comparative sequence analysis of the sHSPs in three complete angiosperms genomes: Arabidopsis thaliana, Populus trichocarpa, and Oryza sativa. Our phylogenetic analysis has identified four additional plant sHSP subfamilies and thus has increased the number of plant sHSP subfamilies from 7 to 11. We have also identified a number of novel sHSP genes in each genome that lack close homologs in other genomes. Using publicly available gene expression data and predicted secondary structures, we have determined that the sHSPs in plants are far more diverse in sequence, expression profile, and in structure than had been previously known. Some of the newly identified subfamilies are not stress regulated, may not posses the highly conserved large oligomer structure, and may not even function as molecular chaperones. We found no consistent evolutionary patterns across the three species studied. For example, gene conversion was found among the sHSPs in O. sativa but not in A. thaliana or P. trichocarpa. Among the three species, P. trichocarpa had the most sHSPs. This was due to an expansion of the cytosolic I sHSPs that was not seen in the other two species. Our analysis indicates that the sHSPs are a dynamic protein family in angiosperms with unexpected levels of diversity. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Barcoding heat shock proteins to human diseases: looking beyond the heat shock response

There are numerous human diseases that are associated with protein misfolding and the formation of toxic protein aggregates. Activating the heat shock response (HSR) – and thus generally restoring the disturbed protein homeostasis associated with such diseases – has often been suggested as a therapeutic strategy. However, most data on activating the HSR or its downstream targets in mouse models of diseases associated with aggregate formation have been rather disappointing. The human chaperonome consists of many more heat shock proteins (HSPs) that are not regulated by the HSR, however, and researchers are now focusing on these as potential therapeutic targets. In this Review, we summarize the existing literature on a set of aggregation diseases and propose that each of them can be characterized or ‘barcoded’ by a different set of HSPs that can rescue specific types of aggregation. Some of these ‘non-canonical’ HSPs have demonstrated effectiveness in vivo, in mouse models of protein-aggregation disease. Interestingly, several of these HSPs also cause diseases when mutated – so-called chaperonopathies – which are also discussed in this Review.KEY WORDS: Chaperonopathies, Heat shock protein, Protein-aggregation diseases     

Heat shock proteins affect RNA processing during the heat shock response of Saccharomyces cerevisiae.

In the yeast Saccharomyces cerevisiae, the splicing of mRNA precursors is disrupted by a severe heat shock. Mild heat treatments prior to severe heat shock protect splicing from disruption, as was previously reported for Drosophila melanogaster. In contrast to D. melanogaster, protein synthesis during the pretreatment is not required to protect splicing in yeast cells. However, protein synthesis is required for the rapid recovery of splicing once it has been disrupted by a sudden severe heat shock. Mutations in two classes of yeast hsp genes affect the pattern of RNA splicing during the heat shock response. First, certain hsp70 mutants, which overproduce other heat shock proteins at normal temperatures, show constitutive protection of splicing at high temperatures and do not require pretreatment. Second, in hsp104 mutants, the recovery of RNA splicing after a severe heat shock is delayed compared with wild-type cells. These results indicate a greater degree of specialization in the protective functions of hsps than has previously been suspected. Some of the proteins (e.g., members of the hsp70 and hsp82 gene families) help to maintain normal cellular processes at higher temperatures. The particular function of hsp104, at least in splicing, is to facilitate recovery of the process once it has been disrupted.     

Fatty acid analysis of four Azospirillum species reveals three groups

Cellular fatty acid composition of 14 strains from the four species of Azospirillum was determined by gas chromatographic analysis. All strains of Azospirillum lipoferum and Azospirillum brasilense were similar in fatty acid data, thus not revealing an expected distinction between the two long established species. Strains of both Azospirillum halopraeferens and Azospirillum amazonense, however, differed significantly from this first group of strains.