This Small Business Innovation Research Phase I project will investigate the feasibility of producing spider silk fibroins in plant trichomes. Synthetic spider silk has great potential as an environmentally-friendly biomaterial because it is very flexible yet has a tensile strength greater than steel. A great need exists for a novel strategy of spider silk fibroin production in a renewable heterologous system that will allow efficient harvest and recovery. The opportunity that is being pursued is the utilization of a natural mechanism for protein production and purification in a genetically-tractable model plant. Our specific technological innovation is the targeted expression of spider silk proteins within the gland cells of leaf surface structures called glandular secreting trichomes, to achieve high levels of heterologous protein production outside of the main plant body. The research objectives will be to drive the expression of spider silk fibroin in trichomes and then investigate novel methods of fibroin recovery. This work will demonstrate that spider silk fibroins can be produced by plants in a cost-effective manner, and will develop a foundation for the large-scale, photosynthetic production of next-generation biomaterials.
The broader impacts/commercial potential of this project will consist of fundamental studies to determine the feasibility of producing a revolutionary industrial biomaterial in a renewable, plant-based system. The results of these studies will not only demonstrate that biomaterials can be produced and purified from plants, but they will also have great implications for understanding about the biosynthetic hardware of specialized plant structures called glandular secreting trichomes. This work should lead to the development of novel ways of achieving industrial biomaterial production without the use of toxic chemicals, and could thus have great societal impact by decreasing the necessity of utilizing large amounts of hazardous compounds in industrial processes. The goal of this project is to develop the foundation for the photosynthetic production of environmentally-friendly biomaterials.
High value proteins are often difficult and expensive to produce in heterologous protein expression systems. Many proteins simply do not express at high levels, and downstream purification steps add significant costs before proteins can be utilized for their intended purposes. Plants are ideal systems for the photosynthetic production of heterologous eukaryotic proteins, but past efforts have been hindered by inefficient recovery strategies. In this Small Business Innovation Research Phase I project, PhylloTech has utilized leaf surface structures called glandular secreting trichomes to produce and recover spider silk, a high value industrial biomaterial that historically has been difficult to express in heterologous systems. The trichome-mediated protein expression strategy utilized in this project has generated a foundation for the large-scale production of spider silk and other high-value proteins in plants. We have demonstrated that plant trichomes have the capacity to produce spider silk, a protein with considerable molecular mass, and we have found that the expression of spider silk outside of the main plant body greatly reduces the purification steps required for recoverability. Future efforts will focus on scaling up the plant-based bioproduction of spider silk and optimizing protein recovery so that we can produce a range of next-generation biomaterials in an environmentally-friendly, photosynthetic system.
