scholarly journals Mitigation of deleterious phenotypes in chloroplast-engineered plants accumulating high levels of foreign proteins

2021 ◽  
Vol 14 (1) ◽  
Author(s):  
Jennifer A. Schmidt ◽  
Lubna V. Richter ◽  
Lisa A. Condoluci ◽  
Beth A. Ahner
Keyword(s):  
Protein Expression ◽  
Protein Production ◽  
Biomass Accumulation ◽  
Cellulase Production ◽  
Protein Yield ◽  
Total Soluble Protein ◽  
Foreign Protein ◽  
Active Components ◽  
Dwarf Phenotype ◽  
Mutant Phenotypes

Abstract Background The global demand for functional proteins is extensive, diverse, and constantly increasing. Medicine, agriculture, and industrial manufacturing all rely on high-quality proteins as major active components or process additives. Historically, these demands have been met by microbial bioreactors that are expensive to operate and maintain, prone to contamination, and relatively inflexible to changing market demands. Well-established crop cultivation techniques coupled with new advancements in genetic engineering may offer a cheaper and more versatile protein production platform. Chloroplast-engineered plants, like tobacco, have the potential to produce large quantities of high-value proteins, but often result in engineered plants with mutant phenotypes. This technology needs to be fine-tuned for commercial applications to maximize target protein yield while maintaining robust plant growth. Results Here, we show that a previously developed Nicotiana tabacum line, TetC-cel6A, can produce an industrial cellulase at levels of up to 28% of total soluble protein (TSP) with a slight dwarf phenotype but no loss in biomass. In seedlings, the dwarf phenotype is recovered by exogenous application of gibberellic acid. We also demonstrate that accumulating foreign protein represents an added burden to the plants’ metabolism that can make them more sensitive to limiting growth conditions such as low nitrogen. The biomass of nitrogen-limited TetC-cel6A plants was found to be as much as 40% lower than wildtype (WT) tobacco, although heterologous cellulase production was not greatly reduced compared to well-fertilized TetC-cel6A plants. Furthermore, cultivation at elevated carbon dioxide (1600 ppm CO2) restored biomass accumulation in TetC-cel6A plants to that of WT, while also increasing total heterologous protein yield (mg Cel6A plant−1) by 50–70%. Conclusions The work reported here demonstrates that well-fertilized tobacco plants have a substantial degree of flexibility in protein metabolism and can accommodate considerable levels of some recombinant proteins without exhibiting deleterious mutant phenotypes. Furthermore, we show that the alterations to protein expression triggered by growth at elevated CO2 can help rebalance endogenous protein expression and/or increase foreign protein production in chloroplast-engineered tobacco.

Expression of Foreign Proteins in Escherichia coli

2021 ◽  
Author(s):  
Ali Iftikhar
Keyword(s):  
Escherichia Coli ◽  
Protein Expression ◽  
Recombinant Proteins ◽  
Expression System ◽  
Maximum Yield ◽  
Protein Yield ◽  
Foreign Protein ◽  
Low Protein ◽  
Prokaryotic Expression System ◽  
Foreign Proteins

Abstract BackgroundOptimization of conditions for the recombinant production of proteins in a prokaryotic expression system is essential as the recombinant proteins impose a metabolic burden on cell's growth leading to low protein yield and low protein expression resulting from cell death.Main textThe concentration of media components is optimized to accommodate for depleted nutrients due to foreign protein expression. The temperature is optimized to reduce proteolytic degradation and accumulation of protein as inclusion bodies in Escherichia coli. The concentration of inducer and time of induction for high protein yield is also optimized. These optimization conditions depend on the promoter under which the gene of interest is present and the characteristics of the target protein.ConclusionIn the past few years, many optimization conditions for the production of recombinant proteins in Escherichia coli have been studied. These conditions depend mainly upon the promoter used to produce protein and the type of protein produced. Optimizing the expression parameters of protein produced in Escherichia coli ensures maximum yield of the desired protein.

scholarly journals Improving Baculovirus Infectivity by Efficiently Embedding Enhancing Factors into Occlusion Bodies

2017 ◽  
Vol 83 (14) ◽  
Author(s):  
Shili Yang ◽  
Lijuan Zhao ◽  
Ruipeng Ma ◽  
Wei Fang ◽  
Jia Hu ◽  
...  
Keyword(s):  
Protein Expression ◽  
Fluorescent Protein ◽  
Expression System ◽  
Agrotis Segetum ◽  
Foreign Protein ◽  
Content Type ◽  
Occlusion Bodies ◽  
Foreign Proteins ◽  
Novel Strategy

ABSTRACT The relatively low infectivity of baculoviruses to their host larvae limits their use as insecticidal agents on a larger scale. In the present study, a novel strategy was developed to efficiently embed foreign proteins into Autographa californica multiple nucleopolyhedrovirus (AcMNPV) occlusion bodies (OBs) to achieve stable expression of foreign proteins and to improve viral infectivity. A recombinant AcMNPV bacmid was constructed by expressing the 150-amino-acid (aa) N-terminal segment of polyhedrin under the control of the p10 promoter and the remaining C-terminal 95-aa segment under the control of the polyhedrin promoter. The recombinant virus formed OBs in Spodoptera frugiperda 9 cells, in which the occlusion-derived viruses were embedded in a manner similar to that for wild-type AcMNPV. Next, the 95-aa polyhedrin C terminus was fused to enhanced green fluorescent protein, and the recombinant AcMNPV formed fluorescent green OBs and was stably passaged in vitro and in vivo. The AcMNPV recombinants were further modified by fusing truncated Agrotis segetum granulovirus enhancin or truncated Cydia pomonella granulovirus ORF13 (GP37) to the C-terminal 95 aa of polyhedrin, and both recombinants were able to form normal OBs. Bioactivity assays indicated that the median lethal concentrations of these two AcMNPV recombinants were 3- to 5-fold lower than that of the control virus. These results suggest that embedding enhancing factors in baculovirus OBs by use of this novel technique may promote efficient and stable foreign protein expression and significantly improve baculovirus infectivity. IMPORTANCE Baculoviruses have been used as bioinsecticides for over 40 years, but their relatively low infectivity to their host larvae limits their use on a larger scale. It has been reported that it is possible to improve baculovirus infectivity by packaging enhancing factors within baculovirus occlusion bodies (OBs); however, so far, the packaging efficiency has been low. In this article, we describe a novel strategy for efficiently embedding foreign proteins into AcMNPV OBs by expressing N- and C-terminal (dimidiate) polyhedrin fragments (150 and 95 amino acids, respectively) as fusions to foreign proteins under the control of the p10 and polyhedrin promoters, respectively. When this strategy was used to embed an enhancing factor (enhancin or GP37) into the baculovirus OBs, 3- to 5-fold increases in baculoviral infectivity were observed. This novel strategy has the potential to create an efficient protein expression system and a highly efficient virus-based system for insecticide production in the future.

Heterologous Expression and Purification of Hagfish Mucus Protein

2021 ◽  
Vol 15 (1) ◽  
pp. 20-32
Author(s):  
Rui Yang ◽  
Ruishuang Sun ◽  
Wenlong Zhu ◽  
QingShuai Zhang ◽  
Debang Liu ◽  
...  
Keyword(s):  
Protein Expression ◽  
Response Surface ◽  
Self Assembly ◽  
Target Protein ◽  
Protein Yield ◽  
Separation And Purification ◽  
Single Factor ◽  
Purification Method ◽  
Iptg Concentration ◽  
Codon Preference

To realize the application and production of hagfish mucus protein, this experiment increased the protein expression and improved its purification method. According to codon preference, the hagfish mucus protein gene was optimized to increase the production of target protein. Then, the protein expression conditions of the host bacteria were optimized, and the IPTG concentration, induction time and supplementation amounts of glycine, threonine, and serine were evaluated in single-factor tests. On the basis of single-factor experiments, with the supplementation of glycine, threonine, and serine as independent variables, the target protein yield was the response value. According to the Box-Behnken central combination design principle of the response surface method, the influence of the respective variables and their interaction on the hagfish mucus protein yield were studied, and the induction conditions were optimized through a combination of Design-Expert software and response surface analysis. The results show that the best induction conditions for EsTKα shake flasks are IPTG concentration 0.6 mmol/L, induction for 12 h, and glycine, threonine, and serine added at 90 mg/L, 90 mg/L, and 9.91 mg/L, respectively, to achieve the highest protein yield of 153.482 mg/L. The IPTG concentration of EsTKγ was 0.8 mmol/L after induction for 12 h, and the amounts of glycine, threonine, and serine were 54 mg/L, 9.01 mg/L, and 11.4 mg/L, respectively. The theoretical best protein yield was 141.97 mg/L. Finally, based on the principle of specific self-assembly between proteins, the two proteins were subjected to gradient dialysis, and the gelled assembled protein was selected by the phase separation method to achieve separation and purification.

scholarly journals Engineering Biology to Construct Microbial Chassis for the Production of Difficult-to-Express Proteins

2020 ◽  
Vol 21 (3) ◽  
pp. 990 ◽  
Author(s):  
Kangsan Kim ◽  
Donghui Choe ◽  
Dae-Hee Lee ◽  
Byung-Kwan Cho
Keyword(s):  
Recombinant Protein ◽  
Protein Expression ◽  
Recombinant Proteins ◽  
Heterologous Protein ◽  
Recombinant Protein Expression ◽  
Cost Effective ◽  
Protein Yield ◽  
Heterologous Protein Expression ◽  
Heterologous Proteins ◽  
Expression Pathways

A large proportion of the recombinant proteins manufactured today rely on microbe-based expression systems owing to their relatively simple and cost-effective production schemes. However, several issues in microbial protein expression, including formation of insoluble aggregates, low protein yield, and cell death are still highly recursive and tricky to optimize. These obstacles are usually rooted in the metabolic capacity of the expression host, limitation of cellular translational machineries, or genetic instability. To this end, several microbial strains having precisely designed genomes have been suggested as a way around the recurrent problems in recombinant protein expression. Already, a growing number of prokaryotic chassis strains have been genome-streamlined to attain superior cellular fitness, recombinant protein yield, and stability of the exogenous expression pathways. In this review, we outline challenges associated with heterologous protein expression, some examples of microbial chassis engineered for the production of recombinant proteins, and emerging tools to optimize the expression of heterologous proteins. In particular, we discuss the synthetic biology approaches to design and build and test genome-reduced microbial chassis that carry desirable characteristics for heterologous protein expression.

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