细菌，昆虫细胞和植物系统：重组蛋白表达在不同的生物工厂的比较分析
Summary
In this study the expression of a target human recombinant protein in different production platforms was compared. We focused on traditional fermenter-based cultures and on plants, describing the set-up of each system and highlighting, on the basis of the reported results, the inherent limits and advantages for each platform.
Abstract
植物为基础的系统被认为是用于生产重组蛋白作为其证据充分的电位为柔性，低成本生产高质量的，生物活性的产品的结果的有价值的平台。
在这项研究中，我们比较了在传统的发酵罐系的细胞培养物（细菌和昆虫）与基于植物的表达系统，无论是瞬时和稳定的靶人重组蛋白的表达。
每个平台，我们所描述的设置，优化和生产过程的长度，最终产品的质量和产量，我们评估了临时的生产成本，具体为所选靶重组蛋白质。
总的来说，我们的结果表明，细菌是不适合用于生产目标蛋白的，由于其不溶性包涵体内积累。另一方面，基于植物的系统是通用的平台吨帽允许生产所选蛋白质在较低的成本比杆状病毒/昆虫细胞系统。尤其是，稳定的转基因系显示最高产量的终产物和瞬时表达的植物最快流程开发。然而，并非所有的重组蛋白可受益于基于植物的系统中，但最好的生产平台应凭经验用逐案的方式来确定，如这里所述。
Introduction
Recombinant proteins are commercially mass-produced in heterologous expression systems with the aid of emerging biotechnology tools. Key factors that have to be considered when choosing the heterologous expression system include: protein quality, functionality, process speed, yield and cost.
In the recombinant protein field, the market for pharmaceuticals is expanding rapidly and, consequently, most biopharmaceuticals produced today are recombinant. Proteins can be expressed in cell cultures of bacteria, yeasts, molds, mammals, plants and insects, as well as in plant systems (either via stable- or transient-transformation) and transgenic animals; each expression system has its inherent advantages and limitations and for each target recombinant protein the optimal production system has to be carefully evaluated.
Plant-based platforms are arising as an important alternative to traditional fermenter-based systems for safe and cost-effective recombinant protein production. Although downstream processing costs are comparable to those of microbial and mammalian cells, the lower up-front investment required for commercial production in plants and the potential economy of scale, provided by cultivation over large areas, are key advantages.
We evaluated plants as bioreactors for the expression of the 65 kDa isoform of human glutamic acid decarboxylase (hGAD65), one of the major autoantigen in Type 1 autoimmune diabetes (T1D). hGAD65 is largely adopted as a marker, both for classifying and monitoring the progression of the disease and its role in T1D prevention is currently under investigation in clinical trials. If these trials are successful, the global demand for recombinant hGAD65 will increase dramatically.
Here, we focus on the expression of the enzymatically inactive counterpart of hGAD65, hGAD65mut, a mutant generated by substituting the lysine residue that binds the cofactor PLP (pyridoxal-5′-phosphate) with an arginine residue (K396R)1.
hGAD65mut retains its immunogenicity and, in plant and insect cells, accumulates up to ten-fold higher than hGAD65, its wild-type counterpart. It was hypothesized that the enzymatic activity of hGAD65 interferes with plant cell metabolism to such an extent that it suppresses its own synthesis, whereas hGAD65mut, the enzymatically-inactive form, can be accumulated in plant cells to higher levels.
For the expression of hGAD65mut, the use of different technologies, widely used in plant biotechnology, was explored here and compared to traditional expression platforms (Escherichia coli and Baculovirus/insect cell-based).
In this work, the recombinant platforms developed for the expression of hGAD65mut comprising traditional and plant-based systems were reviewed and compared on the basis of process speed and yield, and of final product quality and functionality.
Protocol
Representative Results
Discussion
在这项研究中三个不同的平台上进行了比较重组人蛋白的表达：细菌细胞，杆状病毒/昆虫细胞和植物。 （ – MagnICON和pK7WG2基础-稳定的即瞬态）的植物为基础的平台是通过利用三个广泛使用的表达技术的进一步探索。选择用于该实验中，hGAD65mut，靶蛋白已在不同的系统13先前已经表示，它的生产和功能是很容易检测和可测量14。
细菌细胞不是一种有效的?…
Disclosures
The authors have nothing to disclose.
Acknowledgements
This work was supported by the COST action ‘Molecular pharming: Plants as a production platform for high-value proteins’ FA0804. The Authors thank Dr Anatoli Giritch and Prof. Yuri Gleba for providing the MagnICON vectors for research purposes.
Materials
| Yeast extract | Sigma | Y1333 | |
| Tryptone | Formedium | TRP03 | |
| Agar Bacteriological Grade | Applichem | A0949 | |
| Sf-900 II SFM medium | Gibco | 10902-088 | |
| Grace’s Insect Medium, unsupplemented | Gibco | 11595-030 | |
| Cellfectin II Reagent | Invitrogen | 10362-100 | |
| MS medium including vitamins | Duchefa Biochemie | M0222 | |
| Sucrose | Duchefa Biochemie | S0809 | |
| Plant agar | Duchefa Biochemie | P1001 | |
| Ampicillin sodium | Duchefa Biochemie | A0104 | Toxic |
| Gentamycin sulphate | Duchefa Biochemie | G0124 | Toxic |
| Ganciclovir | Invitrogen | I2562-023 | |
| Carbenicillin disodium | Duchefa Biochemie | C0109 | Toxic |
| Kanamycin sulfate | Sigma | K4000 | Toxic |
| Rifampicin | Duchefa Biochemie | R0146 | Toxic – 25 mg/ml stock in DMSO |
| Streptomycin sulfate | Duchefa Biochemie | S0148 | Toxic |
| Spectinomycin dihydrochloride | Duchefa Biochemie | S0188 | |
| IPTG (Isopropil-β-D-1-tiogalattopiranoside) | Sigma | I5502 | Toxic |
| MES hydrate | Sigma | M8250 | |
| MgCl2 | Biochemical | 436994U | |
| Acetosyringone | Sigma | D134406 | Toxic – 0.1 M stock in DMSO |
| Syringe (1 ml) | Terumo | ||
| MgSO4 | Fluka | 63136 | |
| BAP (6-Benzylaminopurine) | Sigma | B3408 | Toxic |
| NAA (Naphtalene acetic acid) | Duchefa Biochemie | N0903 | Irritant |
| Cefotaxime | Mylan generics | ||
| Trizma base | Sigma | T1503 | Adjust pH with 1 N HCl to make Tris-HCl buffer |
| HCl | Sigma | H1758 | Corrosive |
| NaCl | Sigma | S3014 | 1 M stock |
| KCl | Sigma | P9541 | |
| Na2HPO4 | Sigma | S7907 | |
| KH2PO4 | Sigma | P9791 | |
| PMSF (Phenylmethanesulfonylfluoride) | Sigma | P7626 | Corrosive, toxic |
| Urea | Sigma | U5378 | |
| β-mercaptoethanol | Sigma | M3148 | Toxic |
| Tween-20 | Sigma | P5927 | |
| Hepes | Sigma | H3375 | |
| DTT (Dithiothreitol) | Sigma | D0632 | Toxic – 1 M stock, store at -20 °C |
| CHAPS | Duchefa Biochemie | C1374 | Toxic |
| Plant protease inhibitor cocktail | Sigma | P9599 | Do not freeze/thaw too many times |
| SDS (Sodium dodecyl sulphate) | Sigma | L3771 | Flammable, toxic, corrosive – 10% stock |
| Glycerol | Sigma | G5516 | |
| Brilliant Blue R-250 | Sigma | B7920 | |
| Isopropanol | Sigma | 24137 | Flammable |
| Acetic acid | Sigma | 27221 | Corrosive |
| Anti-Glutamic acid decarboxylase 65/67 | Sigma | G5163 | Do not freeze/thaw too many times |
| Horseradish peroxidase (HRP)-conjugate anti-rabbit antibody | Sigma | A6154 | Do not freeze/thaw too many times |
| Sf9 Cells | Life Technologies | 11496 | |
| BL21 Competent E.coli | New England Biolabs | C2530H | |
| Protein A Sepharose | Sigma | P2545 | |
| Cell culture plates | Sigma | CLS3516 | |
| Radio Immuno Assay kit | Techno Genetics | 12650805 | Radioactive material |
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