Papaya, which is mainly cultivated in the southeastern region of China, is one of the four famous fruits in Lingnan. It is favored by people because of its edible and medicinal value. Fructose-6-phosphate, 2-kinase/fructose-2, 6-bisphosphatase (F2KP) is a unique bifunctional enzyme with a kinase domain and an esterase domain that catalyzes the synthesis and degradation of fructose-2, 6-bisphosphate (Fru-2, 6-P₂), an important regulator of glucose metabolism in organisms. In order to study the function of the gene CpF2KP encoding the enzyme in papaya, it is particularly important to obtain the target protein. In this study, the coding sequence (CDS) of CpF2KP, with a full-length of 2 274 bp, was got from the papaya genome. The amplified sequence of full-length CDS was cloned into the vector PGEX-4T-1 which was double digested with EcoR I and BamH I. The amplified sequence was constructed into a prokaryotic expression vector by genetic recombination. After exploring the induction conditions, the results of SDS-PAGE showed that the size of the recombinant GST-CpF2KP protein was about 110 kDa. The optimum IPTG concentration and temperature for CpF2KP induction were 0.5 mmol/L and 28 ℃, respectively. The purified sin[A1] gle target protein was obtained after purifying the induced CpF2KP protein. In addition, the expression level of this gene was detected in different tissues, and showed that the gene was expressed at the highest level in seeds and the lowest in pulp. This study provides an important basis for further revealing the function of CpF2KP protein and studying the involved biological processes of this gene in papaya.
Humans ; Carica/genetics* ; Recombinant Proteins ; Carbohydrate Metabolism ; Cloning, Molecular ; China

ERα-36 is a novel subtype of estrogen receptor α which promotes tumor cell proliferation, invasion and drug resistance, and it serves as a therapeutic target. However, only small-molecule compounds targeting ERα-36 are under development as anticancer drugs at present. Gene therapy approach targeting ERα-36 can be explored using recombinant adenovirus armed with decoy receptor. The recombinant shuttle plasmid pDC316-Ig κ-ERα-36-Fc-GFP was constructed via genetic engineering to express an Ig κ-signaling peptide-leading secretory recombinant fusion protein ERα-36-Fc. The recombinant adenovirus Ad-ERα-36-Fc-GFP was subsequently packaged, characterized and amplified using AdMax^TM adenovirus packaging system. The expression of fusion protein and functional outcome of Ad-ERα-36-Fc-GFP transduction were further analyzed with triple-negative breast cancer MDA-MB-231 cells. Results showed that the recombinant adenovirus Ad-ERα-36-Fc-GFP was successfully generated. The virus effectively infected MDA-MB-231 cells which resulted in expression and secretion of the recombinant fusion protein ERα-36-Fc, leading to significant inhibition of EGFR/ERK signaling pathway. Preparation of the recombinant adenovirus Ad-ERα-36-Fc-GFP provides a basis for further investigation on cancer gene therapy targeting ERα-36.
Adenoviridae/genetics* ; Cell Proliferation ; Estrogen Receptor alpha/metabolism* ; Recombinant Proteins ; Transfection

In order to construct a recombinant replication deficient human type 5 adenovirus (Ad5) expressing a foot-and-mouth disease virus (FMDV) capsid protein, specific primers for P12A and 3B3C genes of FMDV-OZK93 were synthesized. The P12A and 3B3C genes were then amplified and connected by fusion PCR, and a recombinant shuttle plasmid pDC316-mCMV-EGFP-P12A3B3C expressing the FMDV-OZK93 capsid protein precursor P12A and 3B3C protease were obtained by inserting the P12A3B3C gene into the pDC316-mCMV-EGFP plasmid. The recombinant adenovirus rAdv-P12A3B3C-OZK93 was subsequently packaged, characterized and amplified using AdMax^TM adenovirus packaging system, and the expression was verified by infecting human embryonic kidney cell HEK-293. The humoral and cellular immunity levels of well-expressed and purified recombinant adenovirus immunized mice were evaluated. The results showed that rAdv-P12A3B3C-OZK93 could be stably passaged and the maximum virus titer reached 1×10^9.1 TCID₅₀/mL. Western blotting and indirect immunofluorescence showed that rAdv-P12A3B3C-OZK93 expressed the FMDV-specific proteins P12A and VP1 in HEK-293 cells. In addition, the PK cell infection experiment confirmed that rAdv-P12A3B3C-OZK93 could infect porcine cells, which is essential for vaccination in pigs. Comparing with the inactivated vaccine group, the recombinant adenovirus could induce higher FMDV-specific IgG antibodies, γ-IFN and IL-10. This indicates that the recombinant adenovirus has good immunity for animal, which is very important for the subsequent development of foot-and-mouth disease vaccine.
Adenoviridae/genetics* ; Adenoviruses, Human/genetics* ; Animals ; Antibodies, Viral ; Capsid/metabolism* ; Capsid Proteins ; Foot-and-Mouth Disease/prevention & control* ; Foot-and-Mouth Disease Virus/genetics* ; HEK293 Cells ; Humans ; Mice ; Recombinant Proteins/genetics* ; Serogroup ; Swine ; Viral Proteins ; Viral Vaccines/genetics*

Phenylalanine ammonia-lyase (PAL), which catalyzes the conversion from L-phenylalanine to trans-cinnamic acid, is a well-known key enzyme and a connecting step between primary and secondary metabolisms in the phenylpropanoid biosynthetic pathway of plants and microbes. Schisandra chinensis, a woody vine plant belonging to the family of Magnoliaceae, is a rich source of dibenzocyclooctadiene lignans exhibiting potent activity. However, the functional role of PAL in the biosynthesis of lignan is relatively limited, compared with those in lignin and flavonoids biosynthesis. Therefore, it is essential to clone and characterize the PAL genes from this valuable medicinal plant. In this study, molecular cloning and characterization of three PAL genes (ScPAL1-3) from S. chinensis was carried out. ScPALs were cloned using RACE PCR. The sequence analysis of the three ScPALs was carried out to give basic characteristics followed by docking analysis. In order to determine their catalytic activity, recombinant protein was obtained by heterologous expression in pCold-TF vector in Escherichia coli (BL21-DE3), followed by Ni-affinity purification. The catalytic product of the purified recombinant proteins was verified using RP-HPLC through comparing with standard compounds. The optimal temperature, pH value and effects of different metal ions were determined. V_max, K_cat and K_m values were determined under the optimal conditions. The expression of three ScPALs in different tissues was also determined. Our work provided essential information for the function of ScPALs.
Cloning, Molecular ; Escherichia coli/metabolism* ; Phenylalanine/metabolism* ; Phenylalanine Ammonia-Lyase/chemistry* ; Recombinant Proteins ; Schisandra/genetics*

Recombinant proteins provide new means for disease treatment, while creating considerable economic benefits. Using commercial crops (mainly tobacco), cereal crops, legumes, and vegetable crops to produce recombinant proteins with medicinal value is a hot-spot for research in "molecular farming". Although many recombinant proteins have been expressed in plants, only a small number have been successfully put into use. To overcome the problems that greatly hamper the development of recombinant protein production in plants, researchers have improved expression systems to increase the yield of recombinant proteins. Starting from analyzing the problems of low yield and/or low biological activity of recombinant proteins produced by plants, the optimization strategies to solve these problems were reviewed, and future research directions for improving the yield of recombinant proteins produced by plants were proposed.
Crops, Agricultural/genetics* ; Plant Proteins/metabolism* ; Plants, Genetically Modified/genetics* ; Recombinant Proteins ; Tobacco/genetics*

Chinese hamster ovary (CHO) cells are the preferred host cells for the production of complex recombinant therapeutic proteins. Adenine phosphoribosyltransferase (APRT) is a key enzyme in the purine biosynthesis step that catalyzes the condensation of adenine with phosphoribosylate to form adenosine phosphate AMP. In this study, the gene editing technique was used to knock out the aprt gene in CHO cells. Subsequently, the biological properties of APRT-KO CHO cell lines were investigated. A control vector expressed an enhanced green fluorescent protein (EGFP) and an attenuation vector (containing an aprt-attenuated expression cassette and EGFP) were constructed and transfected into APRT-deficient and wild-type CHO cells, respectively. The stable transfected cell pools were subcultured for 60 generations and the mean fluorescence intensity of EGFP in the recombinant CHO cells was detected by flow cytometry to analyze the EGFP expression stability. PCR amplification and sequencing showed that the aprt gene in CHO cell was successfully knocked out. The obtained APRT-deficient CHO cell line had no significant difference from the wild-type CHO cells in terms of cell morphology, growth, proliferation, and doubling time. The transient expression results indicated that compared with the wild-type CHO cells, the expression of EGFP in the APRT-deficient CHO cells transfected with the control vector and the attenuation vector increased by 42%±6% and 56%±9%, respectively. Especially, the EGFP expression levels in APRT-deficient cells transfected with the attenuation vector were significantly higher than those in wild-type CHO cells (P < 0.05). The findings suggest that the APRT-deficient CHO cell line can significantly improve the long-term expression stability of recombinant proteins. This may provide an effective cell engineering strategy for establishing an efficient and stable CHO cell expression system.
Adenine/metabolism* ; Adenine Nucleotides ; Adenine Phosphoribosyltransferase/genetics* ; Adenosine Monophosphate ; Animals ; CHO Cells ; Cricetinae ; Cricetulus ; Recombinant Proteins/genetics*

Antioxidant enzymes fused with cell-penetrating peptides could enter cells and protect cells from irradiation damage. However, the unselective transmembrane ability of cell-penetrating peptide may also bring antioxidant enzymes into tumor cells, thus protecting tumor cells and consequently reducing the efficacy of radiotherapy. There are active matrix metalloproteinase (MMP)-2 or MMP-9 in most tumor cellular microenvironments. Therefore, a fusion protein containing an MMP-2/9 cleavable substrate peptide X, a cell-penetrating peptide R9, a glutathione S-transferase (GST), and a human Cu, Zn superoxide dismutase (SOD1), was designed and named GST-SOD1-X-R9. In the tumor microenvironment, GST-SOD1-X-R9 would lose its cell-penetrating peptide and could not enter tumor cells due to the cleavage of substrate X by active MMP-2/9, thereby achieving selected entering normal cells. The complete nucleotide sequence of SOD1-X-R9 was synthesized and inserted into the prokaryotic expression vector pGEX-4T-1. The pGEX4T-1-SOD1-X-R9 recombinant plasmid was obtained, and soluble expression of the fusion protein was achieved. GST-SOD1-X-R9 was purified by ammonium sulfate precipitation and GST affinity chromatography. The molecular weight of the fusion protein was approximately 47 kDa, consistent with the theoretical value. The SOD and GST activities were 2 954 U/mg and 328 U/mg, respectively. Stability test suggested that almost no change in either SOD activity or GST activity of GST-SOD1-X-R9 was observed under physiological conditions. The fusion protein could be partially digested by collagenase Ⅳ in solution. Subsequently, the effect of MMP-2/9 activity on transmembrane ability of the fusion protein was tested using 2D and 3D cultured HepG2 cells. Little extracellular MMP-2 activity of HepG2 cells was observed under 2D culture condition. While under the 3D culture model, the size and the MMP-2 activity of the HepG2 tumor spheroid increased daily. GST-SOD1-R9 proteins showed the same transmembrane efficiency in 2D cultured HepG2 cells, but the transmembrane efficiency of GST-SOD1-X-R9 in 3D cultured HepG2 spheres was reduced remarkably. This study provided a basis for further investigating the selectively protective effect of GST-SOD1-X-R9 against oxidative damage in normal cells.
Ammonium Sulfate ; Antioxidants ; Cell-Penetrating Peptides/pharmacology* ; Endopeptidases ; Glutathione Transferase/metabolism* ; Humans ; Matrix Metalloproteinase 2/genetics* ; Matrix Metalloproteinase 9/genetics* ; Recombinant Fusion Proteins ; Recombinant Proteins ; Superoxide Dismutase/metabolism* ; Superoxide Dismutase-1

The aim of this study was to construct a recombinant adenovirus expressing extracellular domain gene of human epidermal growth factor receptor variant Ⅲ (EGFRvIII ECD), and to prepare single domain antibody targeting EGFRvIII ECD by immunizing camels and constructing phage display antibody library. Total RNA was extracted from human prostate cancer cell line PC-3 cells and reversely transcribed into cDNA. EGFRvIII ECD gene was amplified using cDNA as template, and ligated into pAdTrack-CMV plasmid vector and transformed into E. coli BJ5183 competent cells containing pAdEasy-1 plasmid for homologous recombination. The recombinant adenovirus expressing EGFRvIII ECD was obtained through transfecting the plasmid into HEK293A cells. The recombinant adenovirus was used to immunize Bactrian camel to construct EGFRvIII ECD specific single domain antibody library. The single domain antibody was obtained by screening the library with EGFRvIII protein and the antibody was expressed, purified and identified. The results showed that recombinant adenovirus expressing EGFRvIII ECD was obtained. The capacity of EGFRvIII specific phage single domain antibody library was 1.4×10⁹. After three rounds of enrichment and screening, thirty-one positive clones binding to EGFRvIII ECD were obtained by phage-ELISA, and the recombinant single domain antibody E14 with highest OD₄₅₀ value was expressed and purified. The recombinant E14 antibody can react with EGFRvIII ECD with high affinity in ELISA assessment. The results indicated that the EGFRvIII specific single domain antibody library with high capacity and diversity was constructed and the single domain antibody with binding activity to EGFRvIII was obtained by screening the library. This study may facilitate the diagnosis and treatment of EGFRvIII targeted malignant tumors in the future.
Adenoviridae/genetics* ; DNA, Complementary ; ErbB Receptors ; Escherichia coli/genetics* ; Genetic Vectors/genetics* ; Humans ; RNA ; Recombinant Proteins/metabolism* ; Single-Domain Antibodies

14-3-3 proteins are important proteins in plants, as they regulate plant growth and development and the response to biotic or abiotic stresses. In this study, a 14-3-3 gene(GenBank accession: OM683281) was screened from the cDNA library of the medicinal species Salvia miltiorrhiza by yeast two-hybrid and cloned. The open reading frame(ORF) was 780 bp, encoding 259 amino a cids. Bioinformatics analysis predicted that the protein was a non-transmembrane protein with the molecular formula of C_(1287)H_(2046)N_(346)O_(422)S_9, relative molecular weight of 29.4 kDa, and no signal peptide. Homologous sequence alignment and phylogenetic tree analysis proved that the protein belonged to 14-3-3 family and had close genetic relationship with the 14-3-3 proteins from Arabidopsis thaliana, Oryza sativa, and Nicotiana tabacum. The 14-3-3 gene was ligated to the prokaryotic expression vector pGEX-4 T-1 and then transformed into Escherichia coli BL21 for the expression of recombinant protein. Real-time fluorescent quantitative PCR showed that the expression of this gene was different among roots, stems, leaves, and flowers of S. miltiorrhiza. To be specific, the highest expression was found in leaves, followed by stems, and the lowest expression was detected in flowers. S. miltiorrhiza plants were treated with 15% PEG(simulation of drought), and hormones salicylic acid, methyl jasmonate, and ethephon, respectively, and the expression of 14-3-3 gene peaked at the early stage of induction. Therefore, the gene can quickly respond to abiotic stresses such as drought and plant hormone treatments such as salicylic acid, jasmonic acid, and ethylene. This study lays the foundation for revealing the molecular mechanism of 14-3-3 protein regulating tanshinone biosynthesis and responding to biotic and abiotic stresses.
14-3-3 Proteins/metabolism* ; Amino Acid Sequence ; Cloning, Molecular ; Ethylenes/metabolism* ; Gene Expression Regulation, Plant ; Hormones/metabolism* ; Phylogeny ; Plant Growth Regulators/pharmacology* ; Plant Proteins/metabolism* ; Recombinant Proteins/genetics* ; Salicylic Acid/metabolism* ; Salvia miltiorrhiza/metabolism*

To enhance recombinant protein production by CHO cells, We compared the impact of overexpression of metabolic enzymes, namely pyruvate carboxylase 2 (PYC2), malate dehydrogenase Ⅱ (MDH2), alanine aminotransferase Ⅰ (ALT1), ornithine transcarbamylase (OTC), carbamoyl phosphate synthetase Ⅰ (CPSⅠ), and metabolism related proteins, namely taurine transporter (TAUT) and Vitreoscilla hemoglobin (VHb), on transient expression of anti-hLAG3 by ExpiCHO-S. Overexpression of these 7 proteins could differentially enhance antibody production. OTC, CPSI, MDH2, and PYC2 overexpression could improve antibody titer by 29.2%, 27.6%, 24.1%, and 20.3%, respectively. Specifically, OTC and MDH2 could obviously improve early-stage antibody production rate and the culture period was shortened by 4 days compared with that of the control. In addition, OTC and MDH2 had little impact on the affinity of anti-hLAG3. In most cases, overexpression of these proteins had little impact on the cell growth of ExpiCHO-S. MDH2 and ALT1 overexpression in H293T cells could also improve antibody production. Overall, overexpression of enzymes involved in cellular metabolism is an effective tool to improve antibody production in transient expression system.
Animals ; CHO Cells ; Cricetinae ; Cricetulus ; Enzymes/metabolism* ; Recombinant Proteins/genetics*