Cloning and heterologous expression of pro-2127,a gene encoding cold-active protease from Pseudoalteromonas sp.QI-1

The psychrotropic bacterium, Pseudoalteromonas sp. QI-I, which produces extracellular cold-active protease, was isolated from Antarctic seawater. The genomic DNA of this bacterium was used to construct a plasmid genomic library with the goal of screening cold-active protease genes. Gene pro-2127 with an open reading frame of 2127 bp encoding protease PRO-2127 was cloned and sequenced. Alignment of amino acid sequences suggested that the precursor of PRO-2127 was a member of subfamily S8A, and that it might contain four domains： a signal peptide, an N-terminal prosequence, a catalytic domain and a C-terminal extension. Amino acids Asp185, His244 and Ser425 might form a catalytic triad. PRO-2127 showed some structural features common to psychrophilic enzymes, such as a decrease in Arg residues and the Arg/（Arg＋Lys） ratio. Heterologous expression of pro-2127 in Escherichia coli BL21 （DE3） by pColdlII was also successfully observed in this study.

Cloning and expression of Hsp22.4 gene from Chaetomium globosum

A study was conducted on the molecular mechanism of small heat shock proteins （sHSPs） in Chaetomium globosum. Heat shock protein 22.4 （Hsp22.4） from C. globosum was cloned and expressed in Escherichia coli. BlastX analysis revealed that the Hsp22.4 gene from C. globosum shared the highest identity in amino acid sequence with a Hsp gene from Neurospora crassa, and the identity between them was 65%. The C. globosum Hsp22.4 gene was inserted into the expressive vector of pGEX-4T-2 and the recombinant plasmid named pGEX-HSE E. coli BL21 transformed with pGEX-HSP plasmid was induced by IPTG, and the expressed proteins were analyzed with SDS-PAGE. A 50 kD protein was specially expressed in E. coli BL21, and the result was consistent with expectation, and showed that the Hsp22.4 gene had been expressed in E. coli. Our study has made a foundation for further studying the function ofsHSPs protein.

Cloning, expression profiling and promoter functional analysis of bone morphogenetic protein 2 in the tongue sole(Cynoglossus semilaevis)

BMP2 plays crucial roles in vertebrate developmental process and acts as a bone inducer during osteogenesis. We present here the molecular cloning of bmp2 cDNA from the marine flatfish Cynoglossus semilaevis, and the analysis of bmp2 expression profiling and promoter function. The full length of bmp2 cDNA sequence is 2 048 bp,which encodes a protein of 422 amino acids. Tissue expression distribution of bmp2 was examined in 14 tissues of mature individuals by quantitative real time PCR（qRT-PCR）. The results revealed that bmp2 was expressed ubiquitously, and the highest expression level was detected in the spinal cord. Moreover, bmp2 expression levels were detected at 15 sampling time points of early developmental stages（egg, larva, juvenile and fingerling stages）.The highest expression level of bmp2 was observed at the gastrula stage, which was about ten times higher than those at the other three embryo stages. Whole-mount in situ hybridization showed that the bmp2 signal was strongly detected at the location of the crown-like larval fin, heart and liver, and slightly expressed in the notochord at one day post hatch（dph）; then the expression of bmp2 started to be concentrated in notochord at three dph. Subsequently, we characterized the 5′-flanking region of bmp2 by testing the promoter activity by Luciferase reporter assays. Positive regulatory region was detected at the location of –179 to ＋109. The predicted transcription factor binding sites（E-box binding factors, zinc finger transcription factor, etc.） in this region might participate in the transcriptional regulation of the bmp2 gene.

Cloning and expression of human arresten gene and effect of its recombinant protein on endothelial cell proliferation

To clone human arresten gene and investigate biological activity of the recombinant protein.Methods Human arresten gene was obtained from the plasmid pGEMArr and subcloned into the BamHⅠ and Pst Ⅰ restriction sites of prokaryotic expression vector pRSET containing T7 promoter.The recombinant plasmid pRSETAN was subsequently transformed into the strain E.coli BL21(DE3),and the target gene was expressed under induction of IPTG.The expressed protein was extracted,purified by Ni 2+ chelation affinity chromatography and refoled.The effect of the recombinant protein on proliferation of human umbilical vein endothelial cells (HUVECs) was also analyzed with the MTT assay.Results Endonuclease digesting and DNA sequencing confirmed that the arresten gene was correctly inserted into the expression vector.The recombinant protein was hightly expressed in the form of inclusion body in the host bacteria after induction.SDS-PAGE analysis revealed that the recombinant protein with a molecular weight of 26×103 amounted to 27% of the total bacterial proteins.The purity of the expected protein could reach over 96% through affinity chromatography.After renaturation,the recombinant protein could reach over 96% through affinity chromatography.After renaturation,the recombinant protein could significantly suppress proliferation of human umbilical vein endothelia cells(HUVECs) induced by vascular endothelial growth factor(VEGF).Conclusion Human arresten gene was successfully cloned into the expression vector pRSET and expressed at high level in Escherichia coli.Purified and refolded arresten protein could effectively inhibit proliferation of vascular endothelia cells.2 refs.

Construction of recombinant plasmid and prokaryotic expression in E. Coli and biological activity analysis of human placenta arresten gene

BACKGROUND: The proliferation and metastasis of cancers depend on angiogenesis. This property provides the feasibility for the treatment of cancer by inhibition of angiogenesis, and many angiogenic inhibitors have been demonstrated to effectively inhibit angiogenesis and consequently the growth of solid cancer. As for the newly identified angiogenesis inhibitor, arresten, some studies have found its high activity on restrainting tumor vessel. This study was to assess the anti-angiogenic activity of arresten. METHODS: The arresten gene was obtained from a healthy puerpera's placenta tissue by the reverse transcriptase-polymerase chain reaction (RT-PCR) method, and molecular cloning to prokaryotic expression plasmid pBV220 by recombination strategy. The prokaryotic expression plasmid pBV220/arr was identified by restriction enzyme digestion and sequenced. The pBV220/arr was transformed into E. coli JM109, DH5α, BL21 and BL21 (DE3) by the CaCl_2 transformation method. The arresten expression level was detected by SDS-PAGE. The expressed product was purlfled, re-naturalized and detected for its biological activity of inhibiting the angiogenesis of chorioallantoic membrane (CAM). RESULTS: The arresten gene was cloned and pBV220/arr was constructed. The arresten expression level of protein was highly increased after pBV220/arr was transformed into E. coli BL21 (DE3). SDS-PAGE showed that the expressed arresten proteins were mainly inclusion bodies and had a molecular weight of 26 kDa. The expressed arresten protein showed evident biological activities. CONCLUSIONS: The successful construction of recombinant plasmid pBV220/arr and the effective expression in E. coil have laid a foundation for further study of its anti-angiogenic function and may pave the way for future antitumor application.

Molecular cloning of genes flhA and flhB_2 for flagellar biosynthesis of Leptospira interrogans and functional prediction of the prokaryotic expressing products

To determine the pathogenic potential of the leptospiral flagella-associated proteins, the genes flhA and flhB2 encoding the biosynthesis of flagella of leptospira interrogans serogroup icterohaemor- rhagiae serovar lai stain 56601 were cloned and their prokaryotic expression systems were constructed. It was demonstrated that the cloned flhA and flhB2 genes had 2118 bp in length and showed 100% and 99.9% of homologies in their nucleotide sequences and 100% and 98.8% of homologies in their putative amino acid sequences respectively, in comparison with those of previously reported. The prokaryotic expression systems under the induction with IPTG could efficiently express the target proteins rFlhA and rFlhB2 with the outputs of approximate 10% of the total bacterial proteins. Based on the sequences of the cloned genes flhA and flhB2, the structural features in associated with pathogenesis and the functions of the target proteins were analyzed with bioinformatics softwares, in which the FlhA was found to have 7 major transmembrane helices, while the FlhB2 had 5 ones. The conserved domains in the FlhA showed high similarity to those of the FHIPEP of the other bacterial FlhA and EscV families, but the conserved domains in the FlhB2 were similar to those of bac-export-2 and EscU families, EscV and EscU families being the protein products of the type IR secretion system in association with pathogenesis. The FlhA and FlhB2 also contained protein kinase C （PKC） and protein tyrosine kinase （PTK） phosphorylation sites, indicating that PKC and PTK of host cells were involved in the internalization and intracellular proliferation in the pathogenesis of microorganisms. All these data leads to a conclusion that the flhA and flhB2 genes of L. interrogans are relatively conserved and their gene products have great potential in the pathogenesis of this organism.

Characterization of two novel heat shock protein 70s and their transcriptional expression patterns in response to thermal stress in adult of Frankliniella occidentalis (Thysanoptera:Thripidae)

Heat shock protein 70（HSP70） is one of the most important members in the heat shock protein family, and plays important roles in the thermotolerance of insect. To explore the molecular mechanism of thermotolerance of Frankliniella occidentalis adults, the difference in the expression of HSP70s in F. occidentalis male or female adults under the thermal stress was studied under the laboratory conditions. Two full length c DNAs of HSP70s gene（Fohsc704 and Fohsc705） were cloned from F. occidentalis by using RT-PCR and RACE. The genomic sequence was demonstrated by genomic validation, and the position and size of the intron were analyzed by sequence analysis of c DNA. Real-time PCR was used to analyze the HSP70 expression patterns. The c DNA of Fohsc704 and Fohsc705 possessed 2 073 and 1 476 bp which encoded 690 and 491 amino acids（aa） with a calculated molecular weight of 75 and 54 k Da, respectively. Four introns in Fohsc704 and six introns in Fohsc705 protein were found. However, the HSP70 protein sequences in our study were ended with EKKN and GIFL, which were different from the reported Fo HSP70s. Various expression patterns of Fohsc704 and Fohsc705 were found in both genders of F. occidentalis under thermal stress. The expression of Fohsc704 and Fohsc705 reached to the highest level at –12 and –8°C in male adults, respectively, and Fohsc705 expressed the highest level at 33°C in female adults. In conclusion, HSP70s of F. occidentalis in our study are novel heat shock proteins. There were difference in expression patterns of the two hsc70s in genders of F. occidentalis, and the two HSP70s play important roles in the thermotolerance of F. occidentalis.

Gene cloning and expression of cadherin in midgut of Helicoverpa armigera and its Cry1A binding region

Cadherins belong to one of the families of animal glycoproteins responsible for cal-cium-dependent cell-cell adhesion.Recent literatures showed that the cadherin-like in midgut of several insects served as the receptor of Bt toxin Cry1A and the variation of cadherin-like is re-lated to insect’s resistance to Cry1A.The full-length cDNA encoding cadherin-like of Helicoverpa armigera is cloned by degenerate PCR and RACE techniques and the gene was designated as BtR-harm,which is 5581 bp in full-length,encoding 1730 amino acid residues(BtR-harm was deposited in GenBank and the accession number is AF519180).Its predicted molecular weight and isoelectric point were 195.39 kDa and 4.23,respectively.The inferred amino acid sequence includes a signal sequence,11 cadherin repeats,a membrane-proximal region,a transmem-brane region and a cytoplasmic region.Sequence analysis indicated that the deduced protein sequence was most similar to the cadherin-like from Heliothis virescens with 84.2%identity and highly similar to three other lepidopteran cadherin from Bombyx mori,Manduca sexta and Pectinophora gossypiella,with the sequence identities of 60.3.6%,57.5%and 51.0%,respec-tively.The cDNA encoding cadherin gene was expressed successfully in E.coli and the recom-binant proteins can bind with Cry1Ac.Truncation analysis and binding experiment of BtR-harm revealed that the Cry1A binding region was a contiguous 244-amino acid sequence,which lo-cated between amino acid 1217 and 1461.Semi-quantitative RT-PCR analysis showed that BtR-harm was highly expressed in midgut of H.armigera,very low expressed in foregut and hindgut and was not expressed in other tissues.After H.armigera producing resistance to Cry1Ac,the expression quantity of BtR-harm significantly decreased in midgut of H.armigera.It is the first confirmation that BtR-harm can function as receptor of Cry1Ac in H.armigera and the binding region was located on a contiguous 244 amino acid sequence,suggesting that the de-crease of expression quantity of BtR-harm is one of the main reasons for H.armigera resistance to Cry1Ac.

Identification and Cloning of Differentially Expressed Genes Involved in the Interaction Between Potato and Phytophthora infestans using a Subtractive Hybridization and cDNA-AFLP Combinational Approach

Using a subtractive hybridization （SH）/cDNA-AFLP combinational approach, differentially expressed genes involved in the potato-Phytophthora infestans interaction were identified. These included genes potentially controlling pathogenesis or avr genes in P. infestans as well as those potentially involved in potato resistance or susceptibility to this pathogen. Forty-one differentially expressed transcript, derived fragments （TDFs）, resulting from the interaction, were cloned and sequenced. Two TDFs, suggested as potential pathogenicity factors, have sequence similarity to N-succinyl diaminopimelate aminotransferase and a transcriptional regulator, TetR family gene, respectively. Two other TDFs, suggested as potential avr genes, have sequence similarity to an EST sequence from Avr41Cf.41Avr91Cf- 9 and a P. infestans avirulence-associated gene, respectively. Genes＇ expression and origin were confirmed using Southern blots, Northern blots and qRT-PCR, he., potential resistance gene DL81 was induced at 12 hpi in the moderately resistant cultivar, whereas it was down-regulated as early as 6 hpi in the susceptible cultivar. On the other hand, DL21 was induced at 6 hpi （3.38-fold） in response to the highly aggressive isolate （US8） and strongly up-regulated thereafter （25.13-fold at 120 hpi.）, whereas it was only slightly up-regulated in response to the weakly aggressive isolate US11 （3.82-fold at 96 hpi）, suggesting its potential involvement as a susceptibility gene.

Cloning of Chinese obese cDNA and its expression in E coli

Objective To obtain the sequence of Chinese obese (OB) cDNA and establish a method of leptin production in China Methods Han Chinese OB cDNA fragment was obtained by reverse transcriptase polymerase chain reaction (RT PCR) with total RNA extracted from human adipocytes and was inserted into the expressing vector pBV220 Then the constructed recombinant plasmid pBV220 OB was transformed to E coli DH5α for leptin expression The recombinant expressing system was confirmed by restriction endonuclease digestion, DNA sequencing and protein expression E coli cells were lysed by high pressure homogenization After cell membrane was extracted, the inclusion bodies were mainly renatured and purified primarily by precipitation with ammonium sulfate and gel chromatography through a Sephadex G75 column The activity of recombinant leptin was determined by its influence on the satiety and weight gain of mice Results Analysis of DNA sequence showed that Han Chinese OB cDNA included the glutamine codon at 49 The amount of recombinant leptin expressed in E coli accounted for 31%-47% of total cellular proteins From 1?L of fermentative bacteria about 40?mg of pure recombinant human leptin was isolated with a purity of being above 95% The recombinant human leptin could reduce food intake and inhibit weight gains in mice Conclusion The glutamine codon at 49 is not missing in Chinese OB gene The biologically active human leptin can be obtained by a relatively simple method of recombinant DNA technology