The robust capacity of skeletal muscle stem cells (SkMSCs, or satellite cells) to regenerate into new muscles in vivo has offered promising therapeutic options for the treatment of degenerative muscle diseases. However, the practical use of SkMSCs to treat muscle diseases is limited, owing to their inability to expand in vitro under defined cultivation conditions without loss of engraftment efficiency. To develop an optimal cultivation condition for SkMSCs, we investigated the behavior of SkMSCs on synthetic maltose-binding protein (MBP)-fibroblast growth factor 2 (FGF2)-immobilized matrix in vitro. We found that the chemically well-defined, xeno-free MBP-FGF2-immobilized matrix effectively supports SkMSC growth without reducing their differentiation potential in vitro. Our data highlights the possible application of the MBP-FGF2 matrix for SkMSC expansion in vitro.
In Vitro Techniques ; Maltose-Binding Proteins ; Muscle, Skeletal ; Muscles ; Stem Cells

To efficiently produce non-specific nuclease (NU) of Serratia marcescens through recombinant overexpression approach and to characterize the purified NU. The nuclease gene was amplified from the genomic DNA of Serratia marcescens by PCR and fused into vector pMAL-c4X with maltose binding protein (MBP) tag. The recombinant vector verified by DNA sequencing was transformed into Escherichia coli BL21. The expressed MBP-NU was purified through the amylose resin and its catalytic characters were analyzed. The results showed the NU gene had 97% identities with the reported S. marcescens nuclease gene and intracellularly expressed in E. coli BL21. The optimal expression conditions were 37 degrees C, 0.75 mmol/L IPTG with 1.5 h induction. The purified MBP-NU exhibited non-specific nuclease activity, able to degrade various nucleic acids, including RNA, single-stranded DNA and double-stranded DNA that was circular or linear. Its optimal temperature was 37 degrees C and optimal pH 8.0. From 1 L culture broth 10.8 mg NU could be purified with a specific activity of 1.11x10(6) U/mg. The catalytic activity of NU was not inhibited by reagents such as EDTA (0.5 mmol/L), PMSF (1 mmol/L) and KCl (150 mmol/L) commonly used in protein purification.
Base Sequence ; Endodeoxyribonucleases ; biosynthesis ; genetics ; Endoribonucleases ; biosynthesis ; genetics ; Escherichia coli ; genetics ; metabolism ; Maltose-Binding Proteins ; genetics ; Molecular Sequence Data ; Recombinant Fusion Proteins ; biosynthesis ; genetics ; isolation & purification ; Serratia marcescens ; enzymology

OBJECTIVE: To recombinant express hepatoma associated gene(HTA) and pre-test the function of HTA to determine the role of HTA in the development of liver cancer. METHODS: HTA338-616 was amplified from HepG2 cells and cloned into the prokaryotic expression vector pET21a(+)-MBP. The proteins MBP and MBP-HTA were induced, purified by His-tag magnetic bead purification kit and identified by Western blot and ELISA. HepG2 cells were stimulated with MBP or MBP-HTA proteins. MTT assay and colony formation assay were employed to examine the proliferation of these cells and the changes of cell cycle distribution were determined by flow cytometry. RESULTS: The prokaryotic expression plasmid pET21a(+)-MBP-HTA was successfully constructed. We got a 52 kD purified purpose protein.The proliferation of HepG2 cells stimulated with MBP-HTA was significantly higher than those stimulated with MBP and negative controls. HepG2 cells stimulated with MBP-HTA showed significant decrease fraction in G1 phase and increase fraction in S phase, and the cell proliferation was enhanced. CONCLUSION HTA protein can significantly promote the proliferation of HepG2 cells, which may be related to the promotion of G1 phase to S phase.
Base Sequence ; Cell Proliferation ; drug effects ; Escherichia coli ; genetics ; metabolism ; Genes, Neoplasm ; physiology ; Genetic Vectors ; Hep G2 Cells ; Humans ; Maltose-Binding Proteins ; biosynthesis ; genetics ; pharmacology ; Molecular Sequence Data ; Neoplasm Proteins ; biosynthesis ; genetics ; pharmacology ; Open Reading Frames ; genetics ; Recombinant Fusion Proteins ; biosynthesis ; genetics ; pharmacology

Human maltase-glucoamylase (MGAM) hydrolyzes linear alpha-1,4-linked oligosaccharide substrates, playing a crucial role in the production of glucose in the human lumen and acting as an efficient drug target for type 2 diabetes and obesity. The amino- and carboxyl-terminal portions of MGAM (MGAM-N and MGAM-C) carry out the same catalytic reaction but have different substrate specificities. In this study, we report crystal structures of MGAM-C alone at a resolution of 3.1 Å, and in complex with its inhibitor acarbose at a resolution of 2.9 Å. Structural studies, combined with biochemical analysis, revealed that a segment of 21 amino acids in the active site of MGAM-C forms additional sugar subsites (+ 2 and + 3 subsites), accounting for the preference for longer substrates of MAGM-C compared with that of MGAM-N. Moreover, we discovered that a single mutation of Trp1251 to tyrosine in MGAM-C imparts a novel catalytic ability to digest branched alpha-1,6-linked oligosaccharides. These results provide important information for understanding the substrate specificity of alpha-glucosidases during the process of terminal starch digestion, and for designing more efficient drugs to control type 2 diabetes or obesity.
Acarbose ; chemistry ; Amino Acid Sequence ; Catalytic Domain ; Crystallography, X-Ray ; Glycoside Hydrolase Inhibitors ; Humans ; Hydrogen Bonding ; Intestines ; enzymology ; Kinetics ; Maltose ; chemistry ; Molecular Sequence Data ; Mutagenesis, Site-Directed ; Mutation, Missense ; Oligosaccharides ; chemistry ; Pichia ; Protein Binding ; Recombinant Proteins ; antagonists & inhibitors ; chemistry ; genetics ; Substrate Specificity ; Surface Properties ; alpha-Glucosidases ; chemistry ; genetics

OBJECTIVETo economically obtain the Abeta peptide for Alzheimer's disease (AD) research by expressing the Abeta peptide fused with the maltose binding protein (MBP) possessing high solubility in E.coli.

METHODSThe cDNA-coding sequence of Abeta peptide was modified by the addition of a BamH I site at the 5' end and a Hind III site at the 3' end using PCR. The modified sequence was ligated into the maltose-binding protein (MBP) fusion expression vector pMAL-c2 containing an thrombin cleavage site, which was transformed into competent E.coli DH5alpha cells. After identification of the single clones by PCR and DNA sequencing, the recombinant plasmid was transformed into E.coli TB1 and induced to express MBP-Abeta fusion protein. The expressed fusion protein was purified using amylose resin column and identified by SDS-PAGE and Western blotting.

RESULTSThe result of DNA sequencing verified the consistency between the inserted sequence and Abeta (1-42) sequence. SDS-PAGE electrophoresis showed that MBP-Abeta fusion protein was highly expressed in E.coli TB1, and Western blotting demonstrated that the purified fusion protein and the separated Abeta peptide could be recognized by specific anti-Abeta (22-35) antibody.

CONCLUSIONMBP-Abeta fusion protein highly expressed in E. coli TB1 cells with enhanced solubility and the separated Abeta peptide with good immunogenicity obtained may lend support to AD research.

Alzheimer Disease ; genetics ; Amyloid beta-Peptides ; biosynthesis ; genetics ; Escherichia coli ; genetics ; metabolism ; Genetic Vectors ; genetics ; Humans ; Maltose-Binding Proteins ; biosynthesis ; genetics ; Recombinant Fusion Proteins ; biosynthesis ; genetics ; isolation & purification

Peroxisome proliferator-activated receptoralpha (PPARalpha) is a ligand-activated transcription factor which plays a pivotal role in the regulations of metabolism. A cDNA encoding ligand binding domain (LBD) of PPARalpha was amplified by RT-PCR from human hepatic tissue and the product was inserted into the downstream of the malE gene in the vector pMAL-p2X,which encodes maltose-binding protein (MBP). The recombinant plasmid containing MBP-PPARalpha gene was transformed into E. coli. TB1, and then the growth conditions of the recombinant strain were studied, which remarkably influenced the final yield of protein expression. With the use of SDS-PAGE and Bio-Rad Quantity One gel image analysis, we found the best expression condition as follows: The induction was started as OD600 reached 0.5 by the adding of IPTG to a final concentration of 0.4 mmol/L, and then the incubation continued 6 hours at 30 degrees C. The maximum yield of fusion protein was 31.34% of the total mass of cytoplasm proteins. Moreover, the soluble form of the target protein is useful for further work on purification and on screening the ligands of PPARalpha.
Carrier Proteins ; biosynthesis ; genetics ; Electrophoresis, Polyacrylamide Gel ; Escherichia coli ; genetics ; metabolism ; Genetic Vectors ; genetics ; Humans ; Ligands ; Maltose-Binding Proteins ; PPAR alpha ; biosynthesis ; genetics ; Recombinant Fusion Proteins ; biosynthesis ; genetics ; isolation & purification

D-amino acid oxidase (DAAO) is one of important industrial enzymes. To increase the solubility and activity of the TvDAAO from Trignoposis variabilis expressed in recombinant Escherichia coli (E. coli), a maltose binding protein (MBP) and Vitreoscilla hemoglobin (VHb) was introduced to fuse with N-terminal of the TvDAAO, respectively. Fusion protein of MBP-TvDAAO was constitutively expressed in JM105/pMKC-DAAO and inductively expressed in JM105/pMKL-DAAO. With respect to the control strain of BL21 (DE3)/pET-DAAO without MBP fusion, the constitutive fusion expression obtained 28% of soluble protein with 3.7 folds of solubility improvement. As for the inductive fusion expression, corresponding results changed to 17% and 1.8 folds, respectively. However, the DAAO activity significantly decreased in the MBP-fusing expression. Fusion protein of VHb-TvDAAO was constructed and inductively expressed in BL21 (DE3)/pET-VDAAO. Its DAAO activity highly reached 3.24 u/mL in flask culture, about 90% increase in contrast to the control without VHb.
Bacterial Proteins ; biosynthesis ; genetics ; Carrier Proteins ; biosynthesis ; genetics ; D-Amino-Acid Oxidase ; biosynthesis ; genetics ; Escherichia coli ; genetics ; metabolism ; Maltose-Binding Proteins ; Recombinant Fusion Proteins ; biosynthesis ; genetics ; Truncated Hemoglobins ; biosynthesis ; genetics ; Yeasts ; enzymology ; genetics

Pulldown assay is an in vitro method for studies of protein-protein interactions, in which tagged proteins are usually expressed as the bait to enrich other proteins that could bind to them. In this technology, the GST tag is broadest used for its modest size and hydrophilic property. In most cases, the GST tag could increase the hydrophility of the fusion protein and help to avoid the formation of inclusion bodies. However, in the other few cases, the target protein may be strongly hydrophobic or have complicated structures that were hard to fold and assemble in correct conformations without champerons, and even the existence of GST tag could not make them soluble. These proteins were always expressed as inclusion bodies and had no functions. LMO2 was a small molecular weight and insoluble protein, in this study, GST system and MBP system were used to express GST-LMO2 and MBP-LMO2 fusion proteins, respectively. We found that GST-LMO2 fusion protein was expressed as inclusion bodies whereas MBP-LMO2 fusion protein was expressed in soluble form. Moreover, the production rate of MBP-LMO2 was also much higher than GST-LMO2. Then MBP-LMO2 fusion proteins and renatured GST-LMO2 fusion proteins were used as bait in pulldown assay to study the interaction between LMO2 and endogenous GATA1 in K562 cells. Western blot analyses showed that both of these proteins could bind to endogenous GATA1 in K562 cells, but recovered GATA1 protein by MBP-LMO2 fusion protein was much more than GST-LMO2 fusion protein. These results suggest that using of MBP system is a helpful attempt in the case of studying small molecular weight, strong hydrophobic proteins.
Adaptor Proteins, Signal Transducing ; Carrier Proteins ; chemistry ; Chemical Precipitation ; DNA-Binding Proteins ; chemistry ; GATA1 Transcription Factor ; chemistry ; Genetic Vectors ; Glutathione Transferase ; chemistry ; Humans ; K562 Cells ; LIM Domain Proteins ; Maltose-Binding Proteins ; Metalloproteins ; chemistry ; Protein Binding ; Protein Interaction Domains and Motifs ; Protein Renaturation ; Proto-Oncogene Proteins ; chemistry ; Recombinant Fusion Proteins ; genetics ; metabolism

OBJECTIVETo identify the interaction partners of a new splicing product of LMO2 gene (LMO2-C), and study its function in K562 cells.

METHODSMaltose binding protein (MBP) pull down and mammalian two-hybrid assay (MTHA) were used to identify the interaction partners of LMO2-C in K562 cells. Semiquantitative RT-PCR was used to detect the expression of hematopoietic specific gene glycoprotein (GPA) in K562 cells.

RESULTSMBP-LMO2-C fusion protein was expressed and purified in soluble form successfully. Endogenous GATA1 and LDB1 proteins were confirmed to bind to LMO2-C by MBP pull down analysis. The MTHA also showed that LMO2-C had comparable binding affinities to LDB1 with LMO2-L, and over expression of LMO2-C prevented LMO2-L from binding to LDB1, the inhibition rate being (81.13 +/- 0.68)%. RT-PCR results showed that the expression level of GPA was reduced [(51.00 +/- 1.58)%] in K562 cells while LMO2-C overexpressed.

CONCLUSIONLMO2-C can bind endogenous GATA1 and LDB1 protein in K562 cells and down regulates the expression of GPA.

Adaptor Proteins, Signal Transducing ; DNA-Binding Proteins ; genetics ; metabolism ; GATA1 Transcription Factor ; metabolism ; Humans ; K562 Cells ; LIM Domain Proteins ; Maltose-Binding Proteins ; Metalloproteins ; genetics ; metabolism ; Periplasmic Binding Proteins ; Proto-Oncogene Proteins ; RNA Splicing ; Transcription Factors ; metabolism ; Two-Hybrid System Techniques

BMP6 is a potent protein for future treatment strategies of bone regeneration as it is a very important regulator of bone homeostasis. Active BMP6 is a dimer containing multidisulfide bonds and is a highly hydrophobic protein prone to aggregation. To obtain soluble and active BMP6 in Escherichia coli, we compared the effects of four N-terminal fusion tags (TRX, GST, MBP and CBD) and N-terminal His6-tag. The expression and solubility were tested under the different conditions (expression hosts, temperatures and inductor concentrations). A series of experiments leads to the finding that the placement of MBP before the BMP6 is best in availing the soluble expression of the protein. Our study alsodemonstrates that in E. coli BL21trxB(DE3) cytoplasm, which is a thioredoxin reductase mutant strain, soluble homodimeric BMP6 can be formed. The overexpressed MBP-BMP6 fusion protein is purified by chromatography, and shown to be functionally active.
Bone Morphogenetic Protein 6 ; biosynthesis ; genetics ; Carrier Proteins ; genetics ; Escherichia coli ; genetics ; metabolism ; Genetic Vectors ; Humans ; Maltose-Binding Proteins ; Recombinant Fusion Proteins ; biosynthesis ; genetics ; isolation & purification ; metabolism ; Solubility ; Transformation, Bacterial