Prokaryotic expression and functional analysis of molecular chaperone Acr2 protein of Mycobacterium tuberculosis / 中国生物制品学杂志

@#Objective To express the molecular chaperone Acr2 protein of Mycobacterium tuberculosis(Mtb)in E.coli and analyze the function. Methods The recombinant plasmid pET-28a-Acr2 was transformed into competent E. coli BL21(DE3),and induced by IPTG. The expressed His-Acr2 protein was purified by Ni-NTA chromatography and SuperdexTM200 10/300 GL gel filtration chromatography to obtain Acr2 protein. The Acr2 protein was refolded by spontaneous refolding and reassembly after thermal denaturation(100 ℃ for 15 min)and chemical denaturation(8 mol/L urea,37 ℃ for 4 h).The secondary structure of Acr2 protein before and after denaturation-renaturation was detected by circular dichroism spectroscopy and non-denaturing SDS-PAGE,and the molecular chaperone function of Acr2 protein in vitro was detected by substrate binding assay. Results The purified Acr2 protein had the relative molecular mass of about 232 000,the purity of over 90%,and the concentration of about 2 mg/mL,which recovered its natural secondary structure after denaturationrenaturation,and formed stable complexes with the denatured malate dehydrogenase(MDH)at 48 ℃. Conclusion The Acr2protein can restore its natural molecular conformation with molecular chaperone activity in vitro after denaturation-renaturation treatment,providing a new strategy for the preparation of Mtb protein antigen with natural activity.

Cloning, induction pattern and prokaryotic expression of a small heat shock protein SmHSP21.8 gene from Salvia miltiorrhiza / 药学学报

In order to reveal the molecular mechanism of the small heat shock proteins (sHSPs) involved in stress resistance and active ingredients accumulation in Salvia miltiorrhiza, a small heat shock protein gene was cloned from Salvia miltiorrhiza by reverse transcription PCR according to the transcriptome data of orange root Salvia miltiorrhiza. The gene is named SmHSP21.8 based on the molecular weight of the protein, and it contains an open reading frame of 585 bp, which encodes 194 amino acids. The results of phylogenetic analysis and amino acid sequence alignment showed that SmHSP21.8 protein belongs to the endoplasmic reticulum (ER) subfamily, and contains a conserved endoplasmic reticulum-specific DPFR-I/V-LE-H/Q-x-P motif at N-terminus. The prokaryotic expression vector pMAL-c2X-SmHSP21.8 was constructed and transformed into E. coli BL21 competent cells. The recombinant protein was successfully expressed after inducted. Temporal and spatial expression analysis showed that SmHSP21.8 gene was the highest expressed in flowers and had significant tissue specificity. The relative expression of the gene was significantly increased in seedlings after induction by 38 ℃, PEG6000, abscisic acid(ABA), and indole-3-acetic acid (IAA), indicating that SmHSP21.8 gene may be involved in abiotic stress such as high temperature and drought, as well as the response to exogenous hormones ABA and IAA. These results lay the foundation for further research on the molecular mechanism of small heat shock proteins involved in adversity stress.

Characterization of differentially expressed stress-associated proteins in starch granule development under heat stress in wheat (Triticum aestivum L.).

Abiotic stress causes abrupt increase in the expression of stress-associated proteins, which provide tolerance by modulating the defense mechanism of plants. Small heat shock proteins (sHSPs) and anti-oxidant enzymes are important for environmental stress tolerance of the plants. In this study, two full-length cDNAs encoding small heat shock protein (sHSP) and superoxide dismutase (SOD), designated as TasHSP and SODI were identified and characterized from C-306 (thermotolerant) and PBW343 (thermosusceptible) cultivars of wheat (Triticum aestivum L.). An alpha crystalline domain was observed in TasHSP and manganese/iron binding domain in case of SODI. Quantitative real-time PCR showed very high transcript level of TasHSP and SOD in C-306 compared to PBW343 at different stages of growth and against differential heat stress (HS). Under differential HS at milky-dough stage, the fold change in transcript of both TasHSP and SOD was observed maximum in C-306, compared to PBW343. Protein profiling and isoenzymes analysis showed the expression of several heat-stable proteins and prominent isoenzymes of SOD in C-306, compared to PBW343. Scanning electron microscopy (SEM) of starch granules showed globular, well-shaped and more numbers of endospermic cells in C-306, compared to defragmented, irregular shaped and shrunken granules in case of PBW343 under HS treatment (42°C for 2 h). Diurnal change in soluble starch synthase (SSS) activity showed an increase in the activity during afternoon (35°C), compared to morning (29°C) and evening (32°C) in both the cultivars. Under heat stress (42°C for 2 h), a drastic decrease in the SSS activity was observed, due to the thermal denaturation of the enzyme. Thermotolerance capacity analyzed using cell membrane stability (CMS) showed significantly higher CMS in case of C-306, compared to PBW343 at different stages of growth. Findings suggest that abundance of TasHSP and SODI during milky-dough stage plays a very important role in starch granule biosynthesis. The mechanism may be further exploited to develop tolerant wheat cultivar with high quality seeds.

Cloning and expression of a small heat and salt tolerant protein (Hsp22) from Chaetomium globosum.

The present study reports molecular characterization of small heat shock protein gene in Indian isolates of Chaetomium globosum, C. perlucidum, C. reflexum, C. cochlioides and C. cupreum. Six isolates of C. globosum and other species showed a band of 630bp using specific primers. Amplified cDNA product of C. globosum (Cg 1) cloned and sequenced showed 603bp open reading frame encoding 200 amino-acids. The protein sequence had a molecular mass of 22 kDa and was therefore, named Hsp22. BlastX analysis revealed that the gene codes for a protein homologous to previously characterized Hsp22.4 gene from C. globosum (AAR36902.1, XP 001229241.1) and shared 95% identity in amino acid sequence. It also showed varying degree of similarities with small Hsp protein from Neurospora spp. (60%), Myceliophthora sp. (59%), Glomerella sp. (50%), Hypocrea sp. (52%), and Fusarium spp. (51%). This gene was further cloned into pET28a (+) and transformed E. coli BL21 cells were induced by IPTG, and the expressed protein of 30 kDa was analyzed by SDS-PAGE. The IPTG induced transformants displayed significantly greater resistance to NaCl and Na2CO3 stresses.

Expression of HSP27 and alphaB-crystallin in Avian Cerebellum during Development / 대한해부학회지

It is well known that small heat shock proteins play a role as molecular chaperone. However, during normal development of the cerebellum, expression and distribution of HSP27 and alphaB-crystallin (alphaBC) which are small heat shock proteins have not been reported. To verify the protective role of HSP27 and alphaBC in neurons and glial cells, we examined the expression and distribution of HSP27 and alphaBC in the developing chick cerebellum using immunoblot, immunohistochemical and double immunofluorescence staining. Expression of both HSP27 and alphaBC was first identified in the cerebellum of the embryonic day 14 (E14) embryo, and was increased at E18. Double immunofluorescence analysis with myelin-basic protein (MBP) demonstrated that alphaBC positive (+) cells were mature myelinating oligodendrocytes. alphaBC+ cells were observed in the white matter of the E14 cerebellum. At E18, there were a number of alphaBC+ cells in the white matter and a few cells in the granular layer of the gray matter. On the other hand, HSP27+ cells were observed in the white matter and the Purkinje cell layer at E14. At E18, HSP27+ signals were observed in Purkinje cells and neurons of cerebellar nucleus as well as oligodendrocytes in the white matter and the granular layer. The results that HSP27 and alphaBC were expressed in specific neurons and glial cells in the developing cerebellum suggest that HSP27 and alphaBC may be involved in the protective mechanism for the apoptosis of neurons and the physiological stress occurred in oligodendrocyts during cell maturation.

TRANSECTION OF THE OPTIC NERVE INDUCES EXPRESSION OF THE SMALL HEAT SHOCK PROTEIN HSP27 IN THE OPTIC PATHWAY OF GOLDEN HAMSTER / 解剖学报

Objective To observe the expression of the small heat shock protein (HSP27) in the optic chiasma (OC), optic tract (OT), dorsal lateral geniculate body(LG) and superior colliculus (SC) of the adult golden hamster after intraorbital transection of the left optic nerve (ON). Methods The experimental animals were left to survive for l, 2, 3, 4, 5, 6, 8 weeks following ON transection. The animals were perfused with formol-saline and brains were excised, sectioned and stained with the immunohistochemistry. The sections were observed under the light microscope, the optical density (A) was measured and the data were analysed statistically. Results Immunohistochemical results indicated that the HSP27-expressions were not different between the right and left side of the OC, OT, LG and SC in normal or sham-operation controls. However, following transection of the left ON, HSP27 immunohistochemical stainings in the right site of OC, OT,LG and SC were increased, comparing with the left side. The maximum difference of HSP27 immunostaining between the right and left side appeared in the lst week following left ON axotomy. The sharply decrease of the A difference occurred at the 2nd week after axotomy with insignificant changes in the subsequent several weeks. And the significant A difference was observed in most time except 6th week. Most of HSP27-positive cells had morphological appearances similar to astrocytes with smaller cell body and numerous processes. Conclusion After the transection of monolateral ON, HSP27 expressions in the contralateral optic pathway of brain increased and persisted up to 8 weeks. This result suggested that the increase of HSP27 expression had something to do with the injury of the optic pathway, but the mechanism and biological significance of the increase in HSP27 expression level required to be studied further.;