Apoplast-Extraction Based Method to Improve the Purity of Plant Produced Recombinant Protein

Summary

The purification of recombinant proteins from plant systems is usually challenged by plant proteins. This work provides a method to effectively extract and purify a secreted recombinant protein from the apoplast of Nicotiana benthamiana.

Abstract

Plants are a newly developing eukaryotic expression system being explored to produce therapeutic proteins. Purification of recombinant proteins from plants is one of the most critical steps in the production process. Typically, proteins were purified from total soluble proteins (TSP), and the presence of miscellaneous intracellular proteins and cytochromes poses challenges for subsequent protein purification steps. Moreover, most therapeutic proteins like antigens and antibodies are secreted to obtain proper glycosylation, and the presence of incompletely modified proteins leads to inconsistent antigen or antibody structures. This work introduces a more effective method to obtain highly purified recombinant proteins from the plant apoplastic space. The recombinant Green fluorescent protein (GFP) is engineered to be secreted into the apoplast of Nicotiana benthamiana and is then extracted using an infiltration-centrifugation method. The GFP-His from the extracted apoplast is then purified by nickel affinity chromatography. In contrast to the traditional methods from TSP, purification from the apoplast produces highly purified recombinant proteins. This represents an important technological improvement for plant production systems.

Introduction

Nowadays, various plant-produced recombinant therapeutic proteins are under study, including antibodies, vaccines, bioactive proteins, enzymes, and small polypeptides^1,2,3,4,5,6. Plants are becoming an increasingly utilized platform for producing therapeutic proteins due to their safety, low cost, and ability to rapidly scale production^7,8. Protein expression and modification in plant systems, along with protein pu....

Protocol

1. Preparation of N. benthamiana plants

1. Place seedling blocks in a tray, add 1 L of water and soak for approximately 2 h until fully saturated.
2. Evenly sprinkle wild-type N. benthamiana seeds on the seedling blocks, cover with a lid, and germinate for 1 week. Grow N. benthamiana in a greenhouse with 18 h photoperiod, 24 °C, 45% relative humidity, and fertilize every 2 weeks.
3. Once the seeds have sprouted, use .......

Discussion

Using plants to produce therapeutic proteins has expanded quickly in recent years^1,2,3,4,5,6. Protein-encoding genes are cloned into expression vectors and delivered into plant tissues via agroinfiltration. After production by plant cells, proteins are purified for downstream applications. Typically, recombinant proteins are .......

Materials

Name	Company	Catalog Number	Comments
100 mesh nylon fine mesh yarn	Guangzhou Huayu Trading limited company	hy-230724-2	For AWF protein extraction
50 ml centrifuge tubes	Vazyme	TCF00150	For centrifuge
ClonExpress II one step cloning kit	Vazyme	C112-02	For clone
FastDigest Sac1	NEB	R3156S	For clone
FastDigest XbaI	NEB	FD0685	For clone
ImageJ 1.5.0	/	/	For greyscale analysis
Large filter	Thermo Fisher	NEST	For filtering
Laser scanning confocal microscopy	Leica SP8		For subcellular localization
Ni sepharose excel	Cytiva	10339806	For protein purification
Precast protein plus gel	YEASEN	36246ES10	For SDS-PAGE
Small filter	Nalgene	1660045	For filtering
SuperSignal West Femto Substrate Trial Kit	Thermo Fisher	34076	For western blotting
Triton X-100	SCR	30188928	To configure the extraction buffer
Type rotaryvang vacuum pump	Zhejiang taizhouqiujing vacuum pump limited company	2XZ-2	For vacuum infiltration
Vertical mixer	Haimen Qilinbel Instrument Manufacturing limited company	BE-1200	For mixing
β-mercaptoethanol	SIGMA	BCBK8223V	To configure the extraction buffer