cDNA cloning and gene expression of ascorbate oxidase in tobacco

A cDNA clone for ascorbate oxidase (AAO) has been isolated from a cDNA library of tobacco (Nicotiana tabacum) cells. The identity of the amino acid sequence deduced from tobacco AAO cDNA to that from pumpkin AAO cDNA was 68%, which was much lower than the identity (80%) between pumpkin and cucumber AAO. AAO activity in tobacco cells was much lower than that in pumpkin cells, whereas the immunoreactive protein in tobacco cells was more abundant than that in pumpkin cells. We suppose that AAO protein in tobacco cells may be less active than that in pumpkin cells. Genomic Southern blotting suggested that AAO in tobacco was encoded by a single-copy gene. Northern blotting revealed that mRNA of AAO was highly expressed in young and growing tissues of tobacco plant.     

cDNA cloning and characterization of the novel genes related to aldehyde dehydrogenase from wild Chinese grape (Vitis pseudoreticulata W. T. Wang).

mRNA differential display was employed to study the gene differential expression of wild Chinese grape (Vitis pseudoreticulata W. T. Wang) infected by Uncinula necator in different periods, a cDNA fragment of T11AC/B0319-456 coded by aldehyde dehydrogenase (ALDH) gene has been obtained. 5' RACE and 3' RACE have been used to clone the whole cDNA sequences of ALDH which consists of three cDNA sequences, whose sizes are 1887, 1956 and 1961 bp, and they encoded a polypeptide size of 537, 524 and 477 designated as VpALDH2a, VpALDH2b and VpALDH1a, respectively. The deduced amino acid sequence shared highly identity with other plants and Human ALDH. Both VpALDH2a and VpALDH2b protein contain putative mitochondrial targeting sequence except VpALDH1a, it indicates that VpALDH2a and VpALDH2b are mitochondrial enzymes, and VpALDH1a is cytosolic enzyme. The VpALDH2a was subcloned into the expression vector pGEX-4T-1, transformed into E.coli BL 21-coden plus induced by IPTG, and about Mr. 85 kD of GST-ALDH fusion protein displayed in SDS-PAGE gel.     

Molecular cloning and characterization of novel heat shock protein 90 gene from a wild <Emphasis Type="Italic">Vitis pseduoreticulata</Emphasis> native to China

Heat shock protein 90 (Hsp90), known as molecular chaperone, is involved in protein folding and assembly in the cell. In the present study, a full-length cDNA named Vitis pseduoreticulta heat shock protein 90 (VpHsp90) (GenBank accession Number:EU239815), encoding a heat shock protein 90, was obtained by degenerated primers and 3′-and 5′-RACE from Vitis pseudoreticulata according to our previously obtained EST sequence (GenBnak accession number:DV182112), putatively known as Hsp90. Comparison of VpHsp90 sequence has revealed that an open reading frame (ORF) consists of 2,100 bp nucleotides and the translated proteins of 699 amino acid residues. The molecular mass of VpHsp90 calculated from the deduced amino acid sequence was 80.2 kDa, Isolectric Point was 4.893, which is in close proximity of Hsp90. The maximum similarity of VpHsp90 at nucleotides level (85%) and protein level (96%) was found to be with Nicotiana tabacum. Phylogenetic tree analysis at both the nucleotides and amino acids levels indicates that Vitis pseduoreticulata, Nicotiana tabacum, and Arabidopsis thaliana Hsp90 sequences comprise one clade, which is closely related to Oryza sativa, Hordeum vulgare and Triticum aestivum Hsp90s. It may be reasonably concluded that VpHsp90 possesses the ancestral gene of Hsp90 similar to that of higher plant species.     

大鼠心肌营养素-1基因在大肠杆菌中的表达与初步纯化

为了实现心肌营养素 - 1 ( CT- 1 )的高效与可溶性表达 ,将 CT- 1基因分别插入到 3种大肠杆菌表达载体 p BV2 2 0、p GEX- 2 T和 p Trx FUS中 ,并实现了表达 ,全菌表达水平分别为 2 .6%、1 6%和 2 5 %。其中 ,CT- 1在 p Trx FUS表达载体中以包含体和可溶性两种方式表达 ,表达水平分别为2 0 .8%和 1 0 .7%。可溶性表达部分经过强阴离子交换和凝胶过滤两步纯化 ,纯度达 80 %以上     

Molecular cloning of a cytosolic ascorbate peroxidase cDNA from cell cultures of sweetpotato and its expression in response to stress

A cDNA encoding a cytosolic ascorbate peroxidase (APX), swAPX1 , was isolated from cell cultures of sweetpotato (Ipomoea batatas) by cDNA library screening, and its expression in the context of various environmental stresses was investigated. swAPX1 contains an ORF of 250 amino acids (27.5 kDa) encoding a protein with a pI value of 5.32. The swAPX1 ORF does not code for a transit peptide, suggesting that the product is a cytosolic isoform. RNA blot analysis showed that swAPX1 gene is expressed in cultured cells and mature leaves, but not in stems, non-storage or storage roots of sweetpotato. The level of swAPX1 RNA progressively increased during cell growth in suspension cultures. In leaf tissues, the gene responded differentially to various abiotic stresses, as revealed by RT-PCR analysis. swAPX1 was highly induced in leaves by wounding, and treatment with methyl viologen (50 M), hydrogen peroxide (440 mM), abscisic acid (ABA; 100 M) or exposure to high temperature (37°C). In addition, the gene was strongly induced in the leaves following inoculation with a bacterial pathogen (Pectobacterium chrysanthemi). These results indicate that swAPX1 may be involved in hydrogen peroxide-detoxification and thus help to overcome the oxidative stress induced by abiotic and biotic stresses.Communicated by G. Jürgens     

Efficient secretory expression of an alkaline pectate lyase gene from Bacillus subtilis in E. coli and the purification and characterization of the protein

The gene encoding pectate lyase (PL) from Bacillus subtilis WSHB04-02 was amplified by PCR, fused with a periplasmic secretion signal peptide sequence, pelB, from pET22b(+), cloned and expressed in Escherichia coli cells using a temperature control vector, pHsh. The recombinant E. coil was grown in a 5 l fermentor. PL was secreted in broth at 22 U l⁻¹ after 20 h when temperature was increased from 30°C to 42°C. The recombinant enzyme was purified to homogeneity as judged by SDS-PAGE. It was optimally active at pH 9.4 and 50°C over 30 min. Analysis of polygalacturonic acid (PGA) degradation products by electrospray ionization (ESI)-mass spectrometry (MS) indicated that PL produced a mixture of unsaturated oligo-galacturonides including unsaturated tri-galacturonic acid and unsaturated bi-galacturonic acid but not unsaturated mono-galacturonic acid.     

Optimizing expression and purification of an ATP-binding gene gsiA from Escherichia coli k-12 by using GFP fusion

The cloning, expression and purification of the glutathione (sulfur) import system ATP-binding protein (gsiA) was carried out. The coding sequence of Escherichia coli gsiA, which encodes the ATP-binding protein of a glutathione importer, was amplified by PCR, and then inserted into a prokaryotic expression vector pWaldo-GFPe harboring green fluorescent protein (GFP) reporter gene. The resulting recombinant plasmid pWaldo-GFP-GsiA was transformed into various E. coli strains, and expression conditions were optimized. The effect of five E. coli expression strains on the production of the recombinant gsiA protein was evaluated. E. coli BL21 (DE3) was found to be the most productive strain for GsiA-GFP fusion-protein expression, most of which was insoluble fraction. However, results from in-gel and Western blot analysis suggested that expression of recombinant GsiA in Rosetta (DE3) provides an efficient source in soluble form. By using GFP as reporter, the most suitable host strain was conveniently obtained, whereby optimizing conditions for overexpression and purification of the proteins for further functional and structural studies, became, not only less laborious, but also time-saving.     

cDNA cloning and mRNA expression of LIM protein gene homologue from the silkworm, Bombyx mori

LIM protein cDNA, from Bombyx mori that contains an open reading frame of 622 bp encoding 94 amino acids, was identified and characterized. The B. mori LIM protein homologue is classified into group 2 LIM proteins that contain glycine-rich LIM domain. B. mori LIM protein mRNA is up-regulated at late embryogenesis and detected in the mid-gut of 5th instar larvae.     

Cloning, characterization and heterologous expression of epoxide hydrolase-encoding cDNA sequences from yeasts belonging to the genera Rhodotorula and Rhodosporidium

Epoxide hydrolase-encoding cDNA sequences were isolated from the basidiomycetous yeast species Rhodosporidium toruloides CBS 349, Rhodosporidium toruloides CBS 14 and Rhodotorula araucariae CBS 6031 in order to evaluate the molecular data and potential application of this type of enzymes. The deduced amino acid sequences were similar to those of the known epoxide hydrolases from Rhodotorula glutinis CBS 8761, Xanthophyllomyces dendrorhous CBS 6938 and Aspergillus niger LCP 521, which all correspond to the group of the microsomal epoxide hydrolases. The epoxide hydrolase encoding cDNAs of the Rhodosporidium and Rhodotorula species were expressed in Escherichia coli. The recombinant strains were able to hydrolyze trans-1-phenyl-1,2-epoxypropane with high enantioselectivity.     

Efficient and rapid protein expression and purification of small high disulfide containing sweet protein brazzein in E. coli

Brazzein protein comes from an edible fruit, which has a long history of being a staple in the local human diet in Africa. The attractive features of brazzein as a potential commercial sweetener include its small size (53 amino acid residues), its stability over wide ranges of temperature and pH, and the similarity of its sweetness to sucrose. Heterologous production of brazzein is complicated by the fact that the protein contains four disulfide bridges and requires a specific N-terminal sequence. Our previous protocol for producing the protein from Escherichia coli involved several steps with low overall yield: expression as a fusion protein, denaturation and renaturation, oxidation of the cysteines, and cleavage by cyanogen bromide at an engineered methionine adjacent to the desired N-terminus. The new protocol described here, which is much faster and leads to a higher yield of native protein, involves the production of brazzein in E. coli as a fusion with SUMO. The isolated protein product contains the brazzein domain folded with correct disulfide bonds formed and is then cleaved with a specific SUMO protease to liberate native brazzein. This protocol represents an important advancement that will enable more efficient research into the interaction between brazzein and the receptor as well as investigations to test the potential of brazzein as a commercially viable natural low calorie sweetener.     

Molecular Cloning of a cDNA Encoding Ribosome Inactivating Protein from Amaranthus viridis and Its Expression in E. coli

In order to isolate a cDNA clone of ribosome inactivating protein (RIP), a cDNA library was constructed in Uni-ZAP XL vector with poly(A) RNA purified from leaves of Amaranthus viridis. To get the probe for screening the library, PCR of phage DNA was conducted using the vector primer and degenerate primer designed from a conserved putative active site of the RIPs. Twenty-six cDNA clones from about 600,000 plaques were isolated, and one of these clones was fully sequenced. It was 1,047 bp and contained an open reading frame encoding 270 amino acids. The deduced amino acid sequence had a putative signal sequence of 17 amino acids and a putative active site (AIQMVAEAARFFKYIE) conserved in other RIPs. E. coli cells expressing A. viridis RIP cDNA did not grow well as compared to control cells, indicating that recombinant A. viridis RIP presumably inactivated E. coli ribosomes. In addition, recombinant A. viridis RIP cDNA produced by E. coli had translation inhibition activity in vitro.     

cDNA cloning and mRNA expression of heat shock protein 90 gene in the haemocytes of Zhikong scallop Chlamys farreri

Heat shock protein 90 (HSP90) is a highly conserved molecular chaperone contributing to the folding, maintenance of structural integrity and proper regulation of a subset of cytosolic proteins. The full-length cDNA of Zhikong scallop Chlamys farreri HSP90 (designated CfHSP90) was cloned by EST and rapid RACE techniques. It was of 2710 bp, including an open reading frame (ORF) of 2181 bp encoding a polypeptide of 726 amino acids with all the five HSP90 family signatures. BLAST analysis revealed that the CfHSP90 gene shared high similarity with other known HSP90 genes. Fluorescent real-time quantitative RT-PCR was used to examine the expression pattern of CfHSP90 mRNA in haemocytes of scallops exposed to Cd²⁺, Pb²⁺ and Cu²⁺ for 10 and 20 days, respectively. All the three heavy metals could induce CfHSP90 expression. There was a clear dose-dependent expression pattern of CfHSP90 after heavy metals exposure for 10 days or 20 days. Different concentrations of the same metal resulted in different effects on CfHSP90 expression. The results indicated that CfHSP90 responded to various heavy metal stresses with a dose-dependent expression pattern as well as exposure time effect, and could be used as a molecular biomarker in a heavy metal polluted environment.     

大肠杆菌K12苹果酸酶的克隆、表达与纯化

以大肠杆菌K12基因组DNA为模板,PCR扩增得到NAD 依赖型苹果酸酶(NAD-ME)的全长基因,并克隆到载体pET24b( )中,得到表达质粒pET24b-ME。在IPTG诱导下,携带pET24b-ME的大肠杆菌BL21(DE3)高效表达分子量约为65 kDa的可溶性蛋白。重组NAD-ME经镍亲和层析纯化,比活达到100 U/mg以上。以上结果为深入研究苹果酸酶生物催化特性及其与辅酶的相互作用奠定了基础。