We constructed bicistronic expression system containing AH6 promoter, 5' UTR and its fore 38 bp sequence from Corynebacterium glutamicum, followed by a conserved Shine-Dalgarno (SD) sequence for xylanase expression. The two major secretory pathways signal peptide in C. glutamicum, Tat (CgR0949) and Sec (CspB) dependent signal peptide were added before xylanase for its secretion. Fed-batch cultivation was done in a 5 L jar for high-level xylanase secretion. The enzyme properties of the purified xylanase were then studied, including the effect of temperature and pH on its activity. The xylanase could be secreted into the culture supernatant when the Sec-dependent signal peptide CspB was used, but none was detected when CgR0949 was used. The secretory production level of xylanase in a flask was 486.2 U/mL and become 1 648.7 U/mL when in a 5 L jar, which was 3.4 fold as in the flask. The optimal pH and temperature of xylanase were pH 4.5 and 45 ℃, respectively. Its activity was 80% of initial activity after pretreatment at 4 ℃ for 24 h at pH 4-11, 95% after incubation below 50 ℃ for 15 min, and 20% when the temperature above 60 ℃. The xylanase could be efficiently secreted into the culture medium by C. glutamicum using its own genetic elements, and the secretion level could be improved through large-scale fed-batch cultivation. This bicistronic expression system can provide a useful tool for heterologous proteins secretion in C. glutamicum. In addition, the catalyze activity of xylanase could be further improved by enzyme properties study.
Corynebacterium glutamicum ; Promoter Regions, Genetic ; Protein Sorting Signals ; Protein Transport

More effective production of human insulin is important, because insulin is the main medication that is used to treat multiple types of diabetes and because many people are suffering from diabetes. The current system of insulin production is based on recombinant DNA technology, and the expression vector is composed of a preproinsulin sequence that is a fused form of an artificial leader peptide and the native proinsulin. It has been reported that the sequence of the leader peptide affects the production of insulin. To analyze how the leader peptide affects the maturation of insulin structurally, we adapted several in silico simulations using 13 artificial proinsulin sequences. Three-dimensional structures of models were predicted and compared. Although their sequences had few differences, the predicted structures were somewhat different. The structures were refined by molecular dynamics simulation, and the energy of each model was estimated. Then, protein-protein docking between the models and trypsin was carried out to compare how efficiently the protease could access the cleavage sites of the proinsulin models. The results showed some concordance with experimental results that have been reported; so, we expect our analysis will be used to predict the optimized sequence of artificial proinsulin for more effective production.
Computer Simulation ; DNA, Recombinant ; Humans* ; Insulin ; Molecular Dynamics Simulation* ; Proinsulin ; Protein Sorting Signals ; Trypsin

Proline-rich proteins (PRPs) are major components of human saliva. In order to know the biological roles of PRPs, we explored the expression pattern and functional protein structures of PRPs by the immunohistochemical and various molecular biological methods. Polyclonal antibody against human gPRP was generated from rabbit by the injection of oral exfoliated cells specially treated by urea and SDS buffer. The PRPs began to be expressed both in the acinar cells and ductal cells from the EIDS (Early Intermediate Developmental Stage) of fetal salivary glands and became intense in the salivary epithelium in the LDS (Late Developmental Stage) and adult salivary glands. The polyclonal antibody against the gPRP showed the cross-reactivity with aPRP and bPRP, these results were relevant to the high homology among subtypes of PRP. However, the simulated protein structures of PRPs showed the characteristic repetitive whorling domains except the N-terminal signal peptide. The whorling domains were also contained the multiple amino acids of glutamine and glycine, which may provide the receptor binding or cross-linking sites of PRPs.
Acinar Cells ; Adult ; Amino Acids ; Epithelium ; Glutamine ; Glycine ; Humans* ; Protein Sorting Signals ; Saliva ; Salivary Glands* ; Urea

The cDNA of endo-1,4-beta-xylanaseA, isolated from Phaenerocheate chrysosporium was expressed in Pichia pastoris. Using either the intrinsic leader peptide of XynA or the alpha-factor signal peptide of Saccharomyces cerevisiae, xylanaseA is efficiently secreted into the medium at maximum concentrations of 1,946 U/L and 2,496 U/L, respectively.
Chrysosporium ; DNA, Complementary ; Phanerochaete ; Pichia ; Polysaccharides ; Protein Sorting Signals ; Saccharomyces cerevisiae

Five patients with myopathy associated with anti-signal recognition peptide antibodies, admitted to our hospital from December 2015 to June 2018, were chosen in our study, and their clinical and pathological manifestations and treatments were retrospectively analyzed. Five patients showed subacute or chronic onset and proximal limb muscle weakness. Serum creatine kinase level was significantly elevated. Immunoblotting assay confirmed the positive anti-signal recognition particle antibody. EMG prompted myogenic damage. Pathological features included muscle degeneration, necrosis with regeneration, visible atrophy and hypertrophic of muscle fiber, connective tissue hyperplasia and a small amount of inflammatory cell infiltration. Immunohistochemical staining showed necrotizing muscle fiber infiltrated with CD4-positive and CD8-positive lymphocytes and CD68-positive macrophages, and no CD20-positive lymphocytes and CD303-positive dendritic cells were observed. Two patients had expressed a bit of c5b-9 positive capillary. Anti-sarcoglycans staining, anti-dysferlin staining and dystrophin staining showed continuous strong positive expression. Follow-up study found that all patients were response to glucocorticoid, and a combination therapy of immunoglobulin and immunosuppression were necessary for some patients.
Autoantibodies ; Follow-Up Studies ; Humans ; Muscular Diseases ; Protein Sorting Signals ; Retrospective Studies

Staphylococcal nuclease A (SNA) may be used to produce bacterial ghosts for further inactivation of host bacteria and elimination of residual genetic materials. It is still controversial if SNA without signal peptide can be secreted to extracellular matrix and if fusion with other peptide is required for its function in the cytoplasm of host bacteria. To clarify this dispute, a series of temperature-inducible plasmids carrying SNA alone or SNA fused with partial sequences of λ phage cro gene (cSNA) or Mycobacterium tuberculosis urease gene (uSNA) were constructed and evaluated in Escherichia coli. Results show that the percentages of inactivated E. coli by SNA, cSNA and uSNA after 4 h of induction were 99.9%, 99.8% and 74.2%, respectively. Moreover, SNA and cSNA in the cytoplasm of host bacteria were initially detectable after 30 min of induction, whereas uSNA was after 1 h. In comparison, SNA and cSNA in culture supernatant were initially detectable 1 h later, whereas uSNA was 2 h later. The nuclease activity in the cytoplasm or supernatant was ranked as follows: SNA > cSNA > uSNA, and the activity in the supernatant was significantly lower than that in the cytoplasm. Furthermore, host genomic DNA was degraded by SNA or cSNA after 2 h of induction but not by uSNA even throughout the whole experiment. In conclusion, this study indicates that SNA, cSNA and uSNA expressed in host bacteria all have nuclease activity, the enzymes can be released to culture media, and fusion with exogenous peptide negatively reduces the nuclease activity of SNA.
Bacteriolysis ; Bacteriophage lambda ; DNA ; chemistry ; Escherichia coli ; Genetic Vectors ; Micrococcal Nuclease ; chemistry ; Plasmids ; Protein Sorting Signals

OBJECTIVETo examine one young female patient with hereditary FVII deficiency and her family members, to observe the gene mutation and clinical phenotype, and to investigate the molecular mechanism of the dysfunction.

METHODSProthrombin time (PT), activated partial thromoploastin time (APTT), fibrinogen (Fg) and FVII activity (FVII:C) and FVII antigen (FVII:Ag) were tested. The gene mutations were sought by DNA sequencing for all of the exons and flanks, 5' and 3' non-translation region of F7 gene. To confirm the role of the found gene mutation, the reverse sequence were determined with Chromas software. To infer the influence of the mutation on the synthesis and function of FVII protein, the FVII protein molecule model containing the found mutation was constructed and the function prediction was performed by the signal peptide prediction database.

RESULTSCompared with the normal population, the proband's PT value was significantly prolonged, and the ratio % FVII:C and that of FVII:Ag were significantly decreased by 1.1% and 0.9%, respectively. The PT, APTT, FVII:C and FVII:Ag of the proband's parents were both normal. Heterozygous 556th nucleotide mutations T/G were found in the proband's and his father's exon lA of F7 gene, with codon CTG turning into CGG, corresponding leucine (L) into arginine (R), i.e Leu12Arg. Function prediction showed that L12R mutations affected the segmentation of different parts of the signal peptide and its corresponding function, which could result in the decline in the mature protein synthesis and its activity obviously. In addition, a spontaneous 3' untranslated region c11814-insAA heterozygous mutation was detected in the proband's F7 gene, while her parents didn't possess this mutation.

CONCLUSIONA new hererozygous mutation (L12R) located in signal peptide of F7 gene is the primary molecular basis of the case with hereditary FVII deficiency. At the same time, the proband's spontaneous 3' non-translation region c11814-insAA mutation may lead to the further reduetion of the FVII synthesis.

Bacillus subtilis is a model strain for studying the physiological and biochemical mechanisms of microorganism, and is also a good chassis cell for industrial application to produce biological agents such as small molecule compounds, bulk chemicals, industrial enzymes, precursors of drugs and health product. In recent years, studies on metabolic engineering methods and strategies of B. subtilis have been increasingly reported, providing good tools and theoretical references for using it as chassis cells to produce biological agents. This review provides information on systematically optimizing the Bacillus subtilis chassis cell by regulating global regulatory factors, simplifying and optimizing the genome, multi-site and multi-dimensional regulating, dynamic regulating through biosensors, membrane protein engineering. For producing the protein reagent, the strain is optimized by optimizing the promoters, signal peptides, secretion components and building the expression system without chemical inducers. In addition, this review also prospects the important issues and directions that need to be focused on in the further optimization of B. subtilis in industrial production.
Bacillus subtilis/genetics* ; Bacterial Proteins/genetics* ; Biotechnology ; Metabolic Engineering ; Promoter Regions, Genetic ; Protein Sorting Signals/genetics*

Dipsaci Radix is one of the commonly used Chinese medicinal materials in China, with a long history. It has the medicinal activities of nourishing liver and kidney, recovering from broken sinews, and treating bone fracture. Triterpenoid saponins are the main functional ingredients of Dipsacus asper. β-Amyrin synthases(β-AS) as a superfamily of oxidosqualene cyclases(OSCs) can catalyze the construction of the skeleton structure of oleanane-type triterpenoid saponins. There are only a few studies about the β-AS in D. asper, and the catalytic mechanism of this enzyme remains to be explored. To enrich the information of β-AS, according to the transcriptome sequencing results, we cloned DaWβ-AS gene from D. asper into a specific vector for heterologous expression in Escherichia coli. In the meantime, real-time PCR was performed to analyze the relative expression of DaWβ-AS in four different tissues of D. asper. The results of RT-qPCR showed DaWβ-AS had the highest expression level in leaves. Bioinformatics results indicated that DaWβ-AS had a conserved domain of PLN03012 superfamily, belonging to the cl31551 superfamily. There was no transmembrane domain or signal peptide in DaWβ-AS. This study provides a scientific basis for revealing the biological pathways of triterpenoid saponins in D. asper, which will facilitate the biosynthesis of the associated saponins and afford reference for the cultivation and development of high-quality resources of D. asper.
Cloning, Molecular ; Computational Biology ; Dipsacaceae/chemistry* ; Intramolecular Transferases ; Protein Sorting Signals ; Saponins/chemistry* ; Triterpenes/chemistry*

Neutrophilic granule protein (NGP) was previously reported as a granular protein of neutrophils in mouse, but the function has not been known clearly. We found the presence of the possible signal peptide in NGP and validated this protein is circulating in the bloodstream. In our findings, NGP is being modified post-translationally in Golgi apparatus and endoplasmic reticulum, which is a universal character of secretory molecules with a signal peptide. The secreted NGP protein could be detected both in vitro and in vivo. NGP has sequence similarity with an antimicrobial protein cathelicidin, and we observed the aspect of inflammation of NGP. Interestingly, NGP interacts with the complex of LPS and LPS binding protein (LBP). This interaction blocks the binding of the complex of LPS and LBP to TLR4 and the downstream inflammatory signals. Furthermore, the inhibitory function of NGP against the inflammatory effect of LPS could be observed in both in vitro and in vivo. With these findings, we report NGP is a novel secretory protein to mask LPS and inhibit its function.
Animals ; Carrier Proteins ; Cytokines ; Endoplasmic Reticulum ; Golgi Apparatus ; In Vitro Techniques ; Inflammation ; Lipopolysaccharides ; Masks ; Mice ; Neutrophils ; Protein Binding ; Protein Sorting Signals