Plant-Based Transient Expression

Cape Bio Pharms uses transient expression to produce recombinant proteins in plants. 

In order to produce a recombinant protein in this manner, genes of interest are first sourced from online databases, expired patents and old papers. These digital sequences are optimised for cloning into plant-based expression vectors, as well as codon optimised. They are then converted into physical DNA through synthesis technology. Agrobacterium Tumefaciens bacteria are transformed with the expression vector containing the gene/s of interest. Once the bacteria have grown to an optimum volume and density, the plants are infiltrated using vaccuum infiltration to transfer the genes of interest into our plant leaves. 

Read More

Plant-Based Transient Expression

Cape Bio Pharms uses transient expression to produce recombinant proteins in plants. 

In order to produce a recombinant protein in this manner, genes of interest are first sourced from online databases, expired patents and old papers. These digital sequences are optimised for cloning into plant-based expression vectors, as well as codon optimised. They are then converted into physical DNA through synthesis technology. Agrobacterium Tumefaciens bacteria are transformed with the expression vector containing the gene/s of interest. Once the bacteria have grown to an optimum volume and density, the plants are infiltrated using vaccuum infiltration to transfer the genes of interest into our plant leaves. 

Proteins are the building blocks of life. Due to conservation during evolution, the basic processes that govern production of proteins from DNA code are highly similar across all eukaryotic cells. This means that a gene from any other organism can be recognised, transcribed and translated by plant molecular machinery. This method has been used to successfully produce complex and high molecular weight proteins with multiple subunits in plants.  Full length immunoglobulins can be constructed in plant cells from light and heavy chain genes infiltrated in separate expression vectors. 

The bacterial system used to infiltrate genes of interest into the plants is based on the soil bacterium Agrobacterium Tumefaciens.  The strain used has had its oncogenes removed to prevent the disease symptoms (galls) from occurring in plants caused by wild-type Agrobacterium infections (i.e. they are disarmed). Nicotiana thus acts as a “bio-processor” to produce proteins of interest based on the genes inserted into our high yielding expression vector. A wonderful history of this bacteria over the last 100 years can be found here: https://www.apsnet.org/edcenter/apsnetfeatures/Pages/Agrobacterium.aspx.

It has long been known that Agrobacterium was the causative agent of crown gall tumors in plants, mainly dicotyledonous plants. Scientists were puzzled however, when they observed that once transformation had taken place, there was no live replicating bacteria found within the tumor cells, they were proliferating independently of the bacteria! What was causing the transformation of these cells then?

In the 1970’s it was discovered that a large plasmid termed the Ti (tumor inducing) plasmid was responsible for the tumor forming function of Agrobacterium3. DNA between the left and right borders of this plasmid is transferred into the plant cells.

The tumor inducing genes have since been removed from the Ti plasmid of Agrobacterium and this plasmid exploited for it's ability to transfer genes into plant cells. Plant based expression vectors have evolved considerably and variuos mechanisms exist to increase the yields of recombinantly produced proteins in plants. 

In this way, genes are not stably introduced into the plant genome and the protein is only transiently produced. The seeds do not contain the introduced gene or protein.