Making proteins for research use in plants
When thinking of “protein”, you may think “steak and eggs”, or “falafel and humus”, or of a sports supplement, perhaps? What about a cancer drug? Or a vaccine? Proteins are among the major players in our bodies, working together in a complex and coordinated way to support our life. Given such an important role in our life and in our health, it is not surprising that they are the object of much research.
Recombinant protein (rProtein) expression is an important research tool, as well as being the technology at basis of bioproduction of biotherapeutics and other valuable molecules/products.
The most used rProtein expression systems are microbial-based – E.coli, Komagataella pastoris (formerly P. pastoris) for example. They are used for the production of many rProteins in research available in the catalogues of the specialist providers, and in the research laboratories. These microbial expression systems are also used in large industrial scale production.
Yeasts are eukaryotic micro-organisms, capable of expressing very complex proteins. However, engineering these organisms to introduce the needed genetic instructions for making novel rProteins is not always trivial. Sometimes it has not been possible to produce the required rProteins in the available yeast systems.
Other eukaryote-based rProtein expression systems have been also more or less extensively deployed in research and some at industrial scales: various types of mammalian cell lines, including human-derived cell lines and mammalians (rProtein expression in milk), insect cell lines and whole insects (larvae), plant cell lines and whole plants.
Since the first publications in the 1980s showing expression of rProteins in whole plants, this expression platform has been also extensively used in research, to express many types of plant, animal and synthetic (i.e. non-natural) recombinant proteins.
Generating plants that produce rProteins over generations (stable production) may be the best option in some cases. The process is not as fast as for example for microbial expression and it is a somewhat cumbersome tool if many protein varieties are being expressed.
Transient expression (mainly using Nicotiana benthamiana) is a relatively fast technology, that matches the needs in research: fast access to rProteins, ability to easily express several variants of the protein and also synthetic constructs, reliable and easy to scale up in a research context.
(check https://pharmafactory.org/Technology-1, for a very clear schematic depiction of this technology).
The basic infrastructure for handling N.benthamiana-based rProtein expression can be relatively inexpensive, making it an attractive option for research laboratories, where budgets for equipment to generate research tools can be challenging.
Plant-based rProtein expression is thus very widespread in plant laboratories and others that have access to plant growth facilities, even when microbial and other expression systems are also available to the laboratories.
Access to the plant-based rProtein production technology is being made easier by initiatives such as the recent collaboration between KBIO, an established user of the plant-based protein expression system, and ZERO, a company working to “build and operate turn-key vertical farms for and with industry leaders in different sectors and in different geographies”, for the rapid deployment of a plant-based molecular farming network (see here).
Some companies have specialized in plant-based technologies and are commercializing a broad range of rProteins for research use, directly, and/or via distributors in the large rProtein catalogues.
Here are some of the companies selling R&D proteins made with plant expression systems:
inVitria – provides safe and effective alternatives to serum and serum proteins, produced in a scalable, non-mammalian recombinant expression system at an ISO9001:2015 certified facility in Kansas, USA.
As one of the longest established companies in this field, inVitria products are currently incorporated in 30 on-market products including 11 therapeutics.
ORF Genetics – develops a portfolio of growth factors, including human growth factors for the stem cell research market, as well as for its own successful skincare brand, BIOEFFECT. Furthermore, ORF Genetics’ latest product, MESOkine, launched in 2020, are animal growth factors specifically developed for the cellular agriculture market, with a strong focus on meat production from stem cells.
CapeBiologix – catalogue of PtX™ proteins currently includes antibodies and antigens that are catered to research and development projects relating to various disease states including inflammation, HIV, COVID-19, and autoimmune disorders. Our high-quality proteins can be used for a variety of applications, including Western Blot, ELISA, and Lateral Flow.
Core Biogenesis – Animal Component-Free and Endotoxin-Free growth factors increase the consistency of cell cultures, which is key to obtain reproducible results and to transition to clinical applications. Core Biogenesis website features three types of FGF.
LenioBio – Almost Living Cell-Free Expression – ALiCE® is a scalable eukaryotic cell-free protein expression system capable of producing even the most complex proteins in under 48 hours. Our proprietary cell-free lysate contains all of the machinery necessary to implement eukaryotic post-translational modifications, without specific optimizations.
LenioBio sells the ALiCE® kit and offers protein services based on their cell-free technology.
Leaf Expression Systems – Leaf uses the SupraVec® technology to enable their partners in the development of therapeutic drugs, diagnostics and vaccines. Leaf Expression Systems’ website includes many proteins that have been made using their systems for protein expression in plants.
Other uses of plant expression systems in R&D:
In an impressive demonstration of the power of the N.benthamiana transient protein expression system, a team of researchers at the Department of Energy’s Lawrence Berkeley National Laboratory (Berkeley Lab) in the USA used it recently to map 400 transition factors in plants. Transcription factors are important proteins for gene regulation, controlling when a gene is “on” or “off”.
“For the first time (…) a genome-scale way to map the regulatory role of transcription factors(…). Their work reveals unprecedented insights into gene regulatory networks and identifies a new library of DNA parts that can be used to optimize genetic engineering efforts in plants.”
These scientists found that there are remarkable similarities and conservation between the gene regulation networks of plants and of other organisms such as yeasts. A more comprehensive map of gene regulation in plants has important implications for the breeding of plants better adapted to higher salinity or other conditions.
Beyond the lab, into medical applications:
Given the versatility of plants as rProtein expression systems, and the relative ease in scaling up production (basically, plant more plants), it is not surprising that medicines and high value products for medical applications are also being made in plants.
A COVID vaccine (COVIFENZ ®), a common swine fever vaccine HERBAVACTM and the VergenixTM (recombinant human collagen) product range for wound and soft tissue repair are examples of approved products made in plants for veterinary and medical use.
There are over 200 companies and teams globally involved in making high value recombinant proteins using plants. You can find out more about plant molecular farming and how plants are being used to produce many valuable products in our earlier blogs and on the links above.