Yuanxing Zhang

East China University of Science and Technology, Shanghai, Shanghai Shi, China

Are you Yuanxing Zhang?

Claim your profile

Publications (173)428.26 Total impact

  • Tongcheng Dai · Na Li · Fajun Han · Hua Zhang · Yuanxing Zhang · Qin Liu
    [Show abstract] [Hide abstract]
    ABSTRACT: Active targeting-ligands have been increasingly used to functionalize nanoparticles for tumour-specific clinical applications. Here we utilize nucleotide adenosine 5′-monophosphate (AMP) as a novel ligand to functionalize polymer-based fluorescent nanoparticles (NPs) for tumour-targeted imaging. We demonstrate that AMP-conjugated NPs (NPs-AMP) efficiently bind to and are following internalized into colon cancer cell CW-2 and breast cancer cell MDA-MB-468 in vitro. RNA interference and inhibitor assays reveal that the targeting effects mainly rely on the specific binding of AMP to adenosine A1 receptor (A1R), which is greatly up-regulated in cancer cells than in matched normal cells. More importantly, NPs-AMP specifically accumulate in the tumour site of colon and breast tumour xenografts and are further internalized into the tumour cells in vivo via tail vein injection, confirming that the high in vitro specificity of AMP can be successfully translated into the in vivo efficacy. Furthermore, NPs-AMP exhibit an active tumour-targeting behaviour in various colon and breast cancer cells, which is positively related to the up-regulation level of A1R in cancer cells, suggesting that AMP potentially suits for more extensive A1R-overexpressing cancer models. This work establishes AMP to be a novel tumour-targeting ligand and provides a promising strategy for future diagnostic or therapeutic applications.
    No preview · Article · Mar 2016 · Biomaterials
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Alcohol oxidase 1 (AOX1) promoter (PAOX1) of Pichia pastoris is the most powerful and commonly used promoter for driving protein expression. However, mechanisms regulating its transcriptional activity are unclear. Here, we identified a Zn(II)2Cys6-type methanol-induced transcription factor 1 (Mit1) and elucidated its roles in regulating PAOX1 activity in response to glycerol and methanol. Mit1 regulated the expression of many genes involved in methanol utilization pathway, including AOX1, but did not participate in peroxisome proliferation and transportation of peroxisomal proteins during methanol metabolism. Structural analysis of Mit1 by performing domain deletions confirmed its specific and critical role in the strict repression of PAOX1 in glycerol medium. Importantly, Mit1, Mxr1, and Prm1, which positively regulated PAOX1 in response to methanol, were bound to PAOX1 at different sites and did not interact with each other. However, these factors cooperatively activated PAOX1 through a cascade. Mxr1 mainly functioned during carbon derepression while Mit1 and Prm1 functioned during methanol induction, with Prm1 transmitting methanol signal to Mit1 by binding to MIT1 promoter (PMIT1), thus increasingly expressing Mit1 and subsequently activating PAOX1.
    Preview · Article · Jan 2016 · Journal of Biological Chemistry
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Light, as an important environmental signal, generally brings about a broad regulation in fungal metabolism. In this work, we aim to explore the light-responded metabolic rules so as to further develop a feasible and effective light regulation strategy for production of anticancer polyketide 1403C by marine fungus Halorosellinia sp. Light derived production enhancement of polyketides was first found in shake flask. To further understand this well working black box, light-responded cell growth, polyketides biosynthesis, metabolic behaviors (enzymes activities and organic acids levels) and mycelia morphology were then investigated in 5-L bioreactor. By comparing cultures under constant irradiation and dark conditions, the entire bioprocess was divided into two phases. During 0 − 60 h, light presumably stimulated relevant metabolism to generate sufficient energy, NADPH and carbon skeleton, particularly malonyl-CoA, which was favorable for mycelia growth and polyketides accumulation. After 60 h, light did harm to biomass and polyketides production. Consequently, a light-dark shift strategy was proposed and verified in 5-L bioreactor. It led to a maximal 1403C production of 1.67 g/L, which was 24% and 74% higher than those obtained under constant irradiation and dark conditions, respectively.
    Full-text · Article · Jan 2016 · Journal of Biotechnology
  • Source
    Tongcheng Dai · Na Li · Yuanxing Zhang · Qin Liu · Lingzhi Zhang
    [Show abstract] [Hide abstract]
    ABSTRACT: Nanoparticles functionalized with active target ligands have been widely used for tumor-specific diagnosis and therapy. The target ligands include antibodies, peptides, proteins, small molecules, and nucleic acid aptamers. Here, we utilize dipeptide Ser-Glu (DIP) as a new ligand to functionalize polymer-based fluorescent nanoparticles (NPs) for pancreatic cancer target imaging. We demonstrate that in the first step, Ser-Glu-conjugated NPs (NPs-DIP) efficiently bind to AsPC-1 and in the following NPs-DIP are internalized into AsPC-1 in vitro. The peptide transporter 1 inhibition experiment reveals that the targeting effects mainly depend on the specific binding of DIP to peptide transporter 1, which is remarkably upregulated in pancreatic cancer cells compared with varied normal cells. Furthermore, NPs-DIP specifically accumulate in the site of pancreatic tumor xenograft and are further internalized into the tumor cells in vivo after intravenous administration, indicating that DIP successfully enhanced nanoparticles internaliza-tion efficacy into tumor cells in vivo. This work establishes Ser-Glu to be a new tumor-targeting ligand and provides a promising tool for future tumor diagnostic or therapeutic applications.
    Preview · Article · Jan 2016 · International Journal of Nanomedicine
  • [Show abstract] [Hide abstract]
    ABSTRACT: Geobacillus sp. 4j, a deep-sea high-salt thermophile, was found to produce thermostable α -amylase. In this work, culture medium and conditions were firstly optimized to enhance production of thermostable α -amylase by statistical methodologies. The resulting extracellular production was increased by 5 times and reached 6.40 U/ml. Then, a high-temperature batch culture of the thermophile in a 15 L house designed bioreactor was studied. The results showed that, a relatively high dissolved oxygen (600 rpm and 15 L/min) and culture temperature of 60°C facilitated both cell growth and α -amylase production. Thus, an efficient fermentation process was established with initial medium pH of 6.0, culture temperature of 60°C and keeping dissolved oxygen above 20%. It gave a α -amylase production of 79 U/ml and productivity of 19804 U/(L · h), which were 10.8 and 208 times higher than those in shake flask, respectively. This work is useful for deep-sea high-salt thermophile culture, where efforts are lacking presently.
    No preview · Article · Dec 2015 · Preparative Biochemistry & Biotechnology
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Libertellenone H (1) was a promising antitumor diterpenoid isolated from Arctic fungus Eutypella sp. D-1, however, its production was very limited. In this study, we investigated the effects of ethanol on cell growth and libertellenone H production. The mycelium in ethanol-feeding cultures was fragmented and dispersed, and the titer of libertellenone H was remarkably increased to 4.88 mg l(-1) in an optimal feeding manner, which was 16.4-fold higher than the control group. To provide an insight into the cell response to ethanol, genes critical to the libertellenone H biosynthesis were successfully cloned and their transcription levels were determined. The results suggested that the gene transcription levels of 3-hydroxy-3-methyl glutaric acyl coenzyme A reductase and geranylgeranyl diphosphate synthase were up-regulated by ethanol stimulation. The results from this study were helpful for further understanding of the ethanol function on diterpenes biosynthesis as well as developing more effective strategies for over-production of these desired secondary metabolites.
    Full-text · Article · Dec 2015 · Bioprocess and Biosystems Engineering
  • Source
    Hesong Liu · Yue Wang · Jingfan Xiao · Qiyao Wang · Qin Liu · Yuanxing Zhang
    [Show abstract] [Hide abstract]
    ABSTRACT: Edwardsiella tarda, the etiologic agent of edwardsiellosis, is a devastating fish pathogen prevailing in worldwide aquaculture industries and accounting for severe economic losses. There is a raising concern about E. tarda being a significant zoonotic pathogen, and it is urgent to develop a rapid detection of this pathogen. This is the first study to develop a test strip for rapid detection of E. tarda in turbot. Mouse monoclonal antibodies (MAbs) and rabbit polyclonal antibody (PAb) against E. tarda were generated from immunization of mice and rabbits with a virulent isolate of E. tarda EIB202. Two MAbs specific to isolates of E. tarda were obtained, and one of them (25C1) was selected to conjugate with colloidal gold as the detector antibody. Rabbit PAb was used as the capture antibody. It was found the strip had no cross-reactivity with non-E. tarda bacterial microbes and the limit of detection (LOD) was 1 × 105 colony-forming units (CFU)/ml. The detection could be visually observed by the naked eye within 5 min. This test strip was verified with a similar detection limit and much less analysis time compared with a dot blot immunoassay (1 × 105 CFU/ml for LOD and 120 min for reaction time). When the samples were mixed with turbot tissue homogenates, strong immunoreactivity was observed over 105 CFU/ml, which suggested that the turbot tissue homogenates did not affect the detection of the strip. Pre-enrichment with homogenized turbot tissue for 12 h could increase the detection limit of the E. tarda present in the sample up to 1 to 10 CFU/ml. In practice, in detecting 20 turbot ascite samples infected by E. tarda, the immunochromatographic test strip showed a high accuracy (100% positive). The immunochromatographic test strip offers great promise for a rapid, simple, and economical method of E. tarda on-site detection, and with different antibodies, it might be used to detect other aquatic pathogens.
    Preview · Article · Dec 2015
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Delivery of antigens by live bacterial carriers can elicit effective humoral and cellular responses and may be an attractive strategy for live bacterial vaccine production through introduction of a vector that expresses an exogenous protective antigen. To overcome the instability and metabolic burden associated with plasmid introduction, alternative strategies, such as the use of in vivo-inducible promoters, have been proposed. However, screening an ideal in vivo-activated promoter with high efficiency and low leak expression in a particular strain poses great challenges to many researchers. In this work, we constructed an in vivo antigen-expressing vector suitable for Edwardsiella tarda, an enteric Gram-negative invasive intracellular pathogen of both animals and humans. By combining quorum sensing genes from Vibrio fischeri with iron uptake regulons, a synthetic binary regulation system (ironQS) for E. tarda was designed. In vitro expression assay demonstrated that the ironQS system is only initiated in the absence of Fe2+ in the medium when the cell density reaches its threshold. The ironQS system was further confirmed in vivo to present an in vivo-triggered and cell density-dependent expression pattern in larvae and adult zebrafish. A recombinant E. tarda vector vaccine candidate WED(ironQS-G) was established by introducing gapA34, which encodes the protective antigen glyceraldehyde-3-phosphate dehydrogenase (GAPDH) from the fish pathogen Aeromonas hydrophila LSA34 into ironQS system, and the immune protection afforded by this vaccine was assessed in turbot (Scophtalmus maximus). Most of the vaccinated fish survived under the challenge with A. hydrophila LSA34 (RPS = 67.0%) or E. tarda EIB202 (RPS = 72.3%). Quorum sensing system has been extensively used in various gene structures in synthetic biology as a well-functioning and population-dependent gene circuit. In this work, the in vivo expression system, ironQS, maintained the high expression efficiency of the quorum sensing circuit and achieved excellent expression regulation of the Fur box. The ironQS system has great potential in applications requiring in vivo protein expression, such as vector vaccines. Considering its high compatibility, ironQS system could function as a universal expression platform for a variety of bacterial hosts.
    Preview · Article · Dec 2015 · Microbial Cell Factories
  • Source
    Tongcheng Dai · Na Li · Lu Liu · Qin Liu · Yuanxing Zhang
    [Show abstract] [Hide abstract]
    ABSTRACT: Quantum dots (QDs) are engineered nanoparticles that possess special optical and electronic properties and have shown great promise for future biomedical applications. In this work, adenosine 5′-monophosphate (AMP), a small biocompatible molecular, was conjugated to organic QDs to produce hydrophilic AMP-QDs. Using macrophage J774A.1 as the cell model, AMP-QDs exhibited both prior imaging property and low toxicity, and more importantly, triggered limited innate immune responses in macrophage, indicating low immunotoxicity in vitro. Using BALB/c mice as the animal model, AMP-QDs were found to be detained in immune organs but did not evoke robust inflammation responses or obvious histopathological abnormalities, which reveals low immunotoxicity in vivo. This work suggests that AMP is an excellent surface ligand with low immunotoxicity, and potentially used in surface modification for more extensive nanoparticles. Electronic supplementary material The online version of this article (doi:10.1186/s11671-015-1100-3) contains supplementary material, which is available to authorized users.
    Preview · Article · Nov 2015 · Nanoscale Research Letters
  • Xiaohong Liu · Hua Zhang · Yuan Gao · Yang Zhang · Haizhen Wu · Yuanxing Zhang
    [Show abstract] [Hide abstract]
    ABSTRACT: Vaccine is one of the efficient candidates to prevent fish disease through activating host immune response in aquaculture. Actually, several vaccines are often administered with adjuvants to increase immunostimulation, especially for some water-based formalin-killed vaccines. However, side effects are inevitable after vaccination of some adjuvants. Therefore, exploration for effective and harmless aquatic adjuvants is urgently needed. In this study, immunoprotection of a formalin-inactivated Vibrio anguillarum vaccine applied with chitosan oligosaccharide (COS) was analyzed. High levels of protection were achieved in zebrafish and turbot vaccinated with inactivated vaccine and COS (RPS of 89.0 ± 4.5% and 80.0 ± 6.9%) compared with fish vaccinated with inactivated vaccine alone (RPS of 47.8 ± 6.6% and 64.7 ± 5.8%) at 4 week post vaccination. Moreover, high antibody reaction and cross-protection against Vibrio alginolyticus and Vibrio harveyi were observed of turbot vaccinated with inactivated vaccine and COS. In conclusion, COS can enhance immunoprotection of a formalin-inactivated V. anguillarum vaccine, significantly activate humoral immune response of host, and be benefit for inhibition against pathogens. Therefore, COS would be a potential adjuvant for aquatic vaccine design in the future.
    No preview · Article · Oct 2015 · Fish & Shellfish Immunology
  • [Show abstract] [Hide abstract]
    ABSTRACT: Objective: The regulator in glycerol repression of Pichia pastoris AOX1 promoter (P AOX1 ) is still unclear. Results: A Cys2His2 zinc finger transcriptional repressor PpNrg1 localized to nucleus and participated in the repression of P AOX1 in P. pastoris in glucose and glycerol. Quantitative real-time PCR revealed that PpNrg1 repressed expression of numerous genes involved in methanol utilization and peroxisome biogenesis in 0.02 % glucose and 1 % (v/v) glycerol. Electrophoretic mobility shift assay and DNase I footprinting assay revealed that PpNrg1 bound to five sites of P AOX1 , including two binding sites of PpMxr1, which is an indispensable activator of P AOX1 in P. pastoris. Conclusion: Transcriptional repressor PpNrg1 suppresses P AOX1 in glucose and glycerol by directly binding to five sites of P AOX1 , including two binding sites of transcriptional activator PpMxr1.
    No preview · Article · Oct 2015 · Biotechnology Letters
  • Meixia Wang · Hao He · Ke Na · Menghao Cai · Xiangshan Zhou · Wenjie Zhao · Yuanxing Zhang
    [Show abstract] [Hide abstract]
    ABSTRACT: Fungi fibrinolytic compound 1 (FGFC1) is a potential fibrinolytic drug candidate produced by the marine fungus Stachybotrys longispora FG216. FGFC1 has an interesting chemical structure, with two symmetrical carbon-chains connected by ornithine. This study demonstrated that the carbon skeleton of FGFC1 was synthesized in a mixed biosynthetic mode based on pathway inhibitor and precursor regulation; the process involves the shikimate and mevalonate pathways. Moreover, the key precursor ornithine was directly integrated into the molecule. Through ornithine regulation, two critical intermediates of FGFC1 were then detected and designated as FGFC2 and FGFC3. The chemical structures of FGFC2 and FGFC3 and their relationships among the four compounds were inferred. We then derived that one molecule of l-ornithine and one molecule of FGFC3 synthesized one molecule of FGFC2; one molecule of l-ornithine and two molecules of FGFC3 synthesized one molecule of FGFC1. Based on bioprocess features, the full fermentation process was divided into four specific phases. Accordingly, feeding of cells with different concentrations of glucose and ornithine showed that FGFC1 production reached 9.92 and 9.6 g/L, respectively, which were increases of 16.3% and 9.6% compared to the control.
    No preview · Article · Oct 2015 · PROCESS BIOCHEMISTRY
  • [Show abstract] [Hide abstract]
    ABSTRACT: The development of aquaculture has been hampered by different aquatic pathogens that can cause edwardsiellosis, vibriosis, or other diseases. Therefore, developing a broad spectrum vaccine against different fish diseases is necessary. In this study, fructose 1,6-bisphosphate aldolase (FBA), a conserved enzyme in the glycolytic pathway, was demonstrated to be located in the non-cytoplasmic components of five aquatic pathogenic bacteria and exhibited remarkable protection and cross-protection against these pathogens in turbot and zebrafish. Further analysis revealed that sera sampled from vaccinated turbot had a high level of specific antibody and bactericidal activity against these pathogens. Meanwhile, the increased expressions of immune response-related genes associated with antigen recognition and presentation indicated that the adaptive immune response was effectively aroused. Taken together, our results suggest that FBA can be utilized as a broad-spectrum vaccine against various pathogenic bacteria of aquaculture in the future. Copyright © 2015. Published by Elsevier Ltd.
    No preview · Article · Aug 2015 · Fish & Shellfish Immunology
  • Jiao Zhou · Hao He · Xiaolong Wang · Jian Lu · Xiangshan Zhou · Menghao Cai · Yuanxing Zhang
    [Show abstract] [Hide abstract]
    ABSTRACT: Streptomyces sp. R-527F, which produces the macrotetrolide antibiotic dinactin, was isolated from the sediments of the Arctic Ocean. In this work, optimization of the nutrients required for dinactin production including medium development and precursor stimulation, were investigated. Optimization of the medium and replacement of polar sea water were achieved using a one factor at a time experiment in conjunction with statistical analysis using methods covering Plackett–Burman design, the steepest descent method and central composite design. Dinactin production in the optimized medium was 160.8 mg/L, which was 47 fold higher than the control. Supplementation of the fermentation with exogenous acetate (1.5 mmol/L), succinate (6 mmol/L), malonate (24 mmol/L) and citrate (6 mmol/L) further enhanced dinactin biosynthesis by 42.7, 122.3, 66.7, and 62.1%, respectively. The precursors, in particular succinate, facilitated sugar use and also increased pH levels. Furthermore, a six-pulse feeding of total 6 mmol/L succinate in a 5 L bioreactor fermentation yielded a maximal production of 279.0 mg/L dinactin, 124.1% higher than that without precursor stimulation. This nutritional regulation process is easy to scale up and holds the potential for adaptation to industrial use. © 2015, The Korean Society for Biotechnology and Bioengineering and Springer-Verlag Berlin Heidelberg.
    No preview · Article · Aug 2015 · Biotechnology and Bioprocess Engineering
  • [Show abstract] [Hide abstract]
    ABSTRACT: A deep-sea thermophile, Geobacillus sp. 4j, was identified to grow on starch and produce thermostable amylase. N-terminally truncated form of Geobacillus sp. 4j α-amylase (Gs4j-amyA) was fused at its N-terminal end with the signal peptide of outer membrane protein A (OmpA) of Escherichia coli. The enzyme was over-expressed in E. coli BL21 with a maximum extracellular production of 130U/ml in shake flask. The yield of the transformant increased 22-fold as, compared with that of the wild strain. The recombinant enzyme purified to apparent homogeneity by metal-affinity chromatography, exhibited a molecular mass of 62kDa. It displayed the maximal activity at 60-65°C and pH 5.5. Its half-life (t1/2) at 80°C was 4.25h with a temperature deactivation energy of 166.3kJ/mol. Compared to three commonly used commercial α-amylases, the Gs4j-amyA exhibited similar thermostable performance to BLA but better than BAA and BSA. It also showed a universally efficient raw starch hydrolysis performance superior to commercial α-amylases at an acidic pH approaching nature of starch slurry. As a new acidic-resistant thermostable α-amylase, it has the potential to bypass the industrial gelatinization step in raw starch hydrolysis. Copyright © 2015. Published by Elsevier Inc.
    No preview · Article · Jun 2015 · Protein Expression and Purification
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Bacterial strains used as backbone for the generation of vaccine prototypes should exhibit an adequate and stable safety profile. Given the fact that live attenuated vaccines often contain some potential risks in virulence recovery and spread infections, new approaches are greatly needed to improve their biological safety. Here, a critically iron-regulated promoter PviuA was screened from V. anguillarum, which was demonstrated to respond to iron-limitation signal both in vitro and in vivo. By using PviuA as a regulatory switch to control the expression of phage P22 lysis cassette 13-19-15, a novel in vivo inducible bacterial lysis system was established in Vibrio anguillarum. This system was proved to be activated by iron-limitation signals and then effectively lyse Vibrio anguillarum both in vitro and in vivo. Further, this controllable bacterial lysis system, after being transformed into a live attenuated V. anguillarum vaccine strain MVAV6203, was confirmed to significantly improve biological safety of the live attenuated vaccine without impairing its immune protection efficacy. Copyright © 2015. Published by Elsevier Ltd.
    Full-text · Article · Jun 2015 · Fish & Shellfish Immunology
  • Ni Ye · Haizhen Wu · Yuanxing Zhang
    [Show abstract] [Hide abstract]
    ABSTRACT: In this study, expressions of some immune parameters among embryos during different development stages from immunized and mock-immunized female fish were compared at day 14 post immunization of the zebrafish brood stock vaccinated with the live attenuated Vibrio anguillarum vaccine MVAV6203. It was found that transcriptional levels of innate immune cell gene markers including spi.1, l-plastin, mpx and gata-1 as well as the myeloid transcription factor c/ebpβ were up-regulated and expressed earlier in embryos of immunized female zebrafish than naive embryos during early development stage. Investigation through ELISA revealed an increase in antibody level in egg cytosol of the female zebrafish following immunization prior to breeding, which was transferred to larvae through eggs. Rise of specific antibody against wild-type V. anguillarumMVM425 was detected at hour 24 post fertilization (p.f.) eggs from immunized brood stock. Extracts of the newly fertilized eggs from immunized zebrafish also showed a higher capability of killing V. anguillarum MVM425. Moreover, larvae from immunized zebrafish also showed a higher capability of resisting the V. anguillarum MVM425 from proliferation after immersion challenge. Interestingly, the higher content of total IgM and specific antibody in eggs and larvae at 24, 48 and 72 h p.f. were positively correlated with their higher antibacterial activity against V. anguillarum MVAV425. Our results showed that, the development of immune cells was enhanced and the maternally derived antibody could protect early embryos and larvae from attack of specific pathogens via vaccination with a live attenuated vaccine.
    No preview · Article · Jun 2015 · Aquaculture Research
  • Xiaohong Liu · Haizhen Wu · Qin Liu · Qiyao Wang · Jingfan Xiao · Yuanxing Zhang
    [Show abstract] [Hide abstract]
    ABSTRACT: Vibrio anguillarum, which is part of normal microflora on fish, is the causative agent of vibriosis in aquaculture. It is speculated that V. anguillarum does not affect the host in most situations, but can cause a severe disease once the host is compromised. In the study reported herein, skin-injured and intestine-injured zebrafish, Danio rerio, were established as a model to mimic the natural infection caused by V. anguillarum when fish suffered an injury to a mucosal surface. Our results showed the lethal dose to 50% of the population (LD50) of skin-injured zebrafish was 6.8 × 103 colony-forming unit (CFU)/mL, which was much lower than intestine-injured zebrafish (1.9 × 106 CFU/mL) or non-injured zebrafish (5.5 × 106 CFU/mL). With the quantitative polymerase chain reaction and immunohistochemical analysis, we found that V. anguillarum proliferated rapidly in the skin and muscle after the bacteria entered into the host via the skin injury. The bacteria were subsequently transported to the immune organs and then caused a systemic infection in the fish. However, mortality of skin-injured zebrafish significantly decreased if the fish were allowed to heal. These results indicate that minimizing injury to the mucosal surfaces of fish, especially the skin, will reduce infections caused by V. anguillarum.
    No preview · Article · Jun 2015 · Journal of the World Aquaculture Society
  • Source
    Teng Chu · Yajun Huang · Mingyu Hou · Qiyao Wang · Jingfan Xiao · Qin Liu · Yuanxing Zhang
    [Show abstract] [Hide abstract]
    ABSTRACT: Quorum sensing system, as a well-functioned population-dependent gene switch, has been widely applied in many gene circuits in synthetic biology. In our work, an efficient cell density-controlled expression system (QS) was established via engineering Vibrio fischeri luxI-luxR quorum sensing system. In order to achieve in vivo programmed gene expression, a synthetic binary regulation circuit (araQS) was constructed by assembling multiple genetic components including quorum quenching protein AiiA and arabinose promoter ParaBAD into the QS system. In vitro expression assay verified that the araQS system was only initiated in the absence of arabinose in the medium at high cell density. In vivo expression assay confirmed that the araQS system presented an in vivo-triggered and cell density-dependent expression pattern. Furthermore, the araQS system was demonstrated to function well in different bacteria, indicating a wide range of bacterial hosts for use. To explore its potential applications in vivo, the araQS system was used to control the production of a heterologous protective antigen in an attenuated Edwardsiella tarda, which successfully evoked efficient immune protection in fish model. This work suggested that the araQS system could program bacterial expression in vivo and might have potential uses, including, but not limited to, bacterial vector vaccine. Copyright © 2015, American Society for Microbiology. All Rights Reserved.
    Preview · Article · May 2015 · Applied and Environmental Microbiology

  • No preview · Article · May 2015 · Fish & Shellfish Immunology