Expressing proteins in tobacco: an interview with Albor Dobon-Alonso from Leaf Expression systems

Several companies participated in SynbiTECH 2019, showcasing their ideas and applications. One of them is Leaf Expression Systems, a startup from Norwich. The company aims to use the tobacco plant Nicotiana benthamiana as an expression platform for protein production. During SynbiTECH, I had the chance to interview Dr Albor Dobon-Alonso, Senior Microbiologist of the company.

What is the advantage of using Nicotiana benthamiana as an expression system as compare to more “traditional” microbial hosts?

There are many advantages of using N. benthamiana as an expression system compare to microbes, but probably the principal is that like humans (and the rest of animals), plants are eukaryotes. This renders the possibility of producing proteins with post-translational modifications, which are needed in many human proteins, such as antibodies. This is not possible to obtain using microbes.

What are the limits of the system?

Even though as I said before plants and animals are both eukaryotes, their metabolisms are not identical, and this could be sometimes a limitation when expressing animal proteins or viral proteins that need specific animal cell processing i.e. if an animal cell specific enzyme is needed for the adequate processing of the target protein. This issue can be overcome by co-expressing the enzyme(s) with the target gene.

How does it feel transitioning from an arguably slow system, A. thaliana, to maybe one of the quickest protein production systems available?

Arabidopsis thaliana is the plant model system and is ideal to study plant molecular biology. But the reality is that I and many other scientists working with A. thaliana use or have used N. benthamiana for their transient expression assays based on its easy transient transformation using Agrobacterium tumefaciens.This is one of the reasons why Nicotiana benthamiana is the plant choice for bulk transient protein expression.

How do you tackle the notorious instability of transient expression?

By definition transient expression is not stable expression. At the moment, we are not interested in generating stable transformants. It is a long and costly process that might be profitable in some few cases, i.e. if a client would want the same product for extended periods of time. In addition, transient expression events occur at higher frequency than stable ones, increasing the yield of the target protein.

Speaking for the plant synthetic biology field in general, could you name a recent breakthrough or study that really gained your interest?

Well, I have to admit that most of my reading on Synthetic Biology deals with novel ways of improving our system and unfortunately I cannot disclose that. Now, I think that nanomachines have an interesting future. Most of them have a protein nature and at Leaf Expression Systems we have successfully generated already VLPs that can be used to efficiently deliver drugs or other products. At the JIC they are doing also very interesting studies, and recently published a rapid gene cloning technique called AgRenSeq, that permits to identify resistance genes in wild crop species and clone them in a matter of months…this used to take years!

What should we expect from Leaf Expression in the next few years?

We have multiple contracts with both commercial and academic clients and we expect to increase our business based on the great advantages and potential of producing proteins in plants. We are also making a great communication effort, such as attending this conference, to describe the advantages of the system. We are also seeking continuously how to improve our manufacturing processes and how to increase our competitiveness.

Albor Dobon-Alonso, originally from Spain, graduated from the UPV (Valencia, Spain) with an MSc. Eng. in Agronomy. He obtained a PhD in Plant Biotechnology in Dr Pablo Tornerois lab at the IBMCP (Valencia, Spain) studying plant pathogen interaction in the model plant Arabidopsis thaliana. After a short postdoc with Professor Pablo Vera he was awarded with a Marie Curie IEF Fellowship to work in the Professor Cristobal Uauy’s Lab at the John Innes Centre where he studied yellow rust disease in wheat, focused in effector discovery. After that, he has been involved in several projects, including exploring the plant production of VLPs in Professor George Lomonossoff’s Lab. Albor joined Leaf Expression Systems in July 2018 and is the Senior Microbiology Scientist of the company.

All images are courtesy of Leaf Expression Systems.