As the market for recombinant proteins continues to skyrocket, biotechs are exploiting a range of options to deal with multiple possibilities. At last month’s CHI “Peptalk” conference, participants explored advances in a number of different expression systems, including bacteria, yeast, mammalian cells, and even cell-free systems.
A widely used protein-expression system is Pichia pastoris. A number of companies that provide molecular reagents also make plasmids and vectors for manipulating Pichia.
The focus of VTU Technology, however, is contract development using the Pichia platform, according to Thomas Purkarthofer, Ph.D., head of the company’s R&D biotechnology division. “Our capabilities are based on molecular technologies available in the public domain, combined with a proprietary set of synthetic variants of the Pichia pastoris AOX1 promoter.”
The AOX1 promoter, inducible with methanol, is known for its power. In order to simplify patent concerns, VTU uses its own optimized plasmids not available publicly, but with no particular IP except for the promoter variants.
With this approach, the company has developed customized high-performance strains for the production of secreted proteins for use in the pharma, chemical, diagnostics, and agricultural industries. The VTU promoter library of synthetic variants of AOX1 spans a range of activities and expression characteristics in order to match promoter properties and specific expression requirements to a given target protein, as well as efficient expression strains for coexpression of auxiliary proteins required by a particular protocol.
These strains were isolated and modified individually in order to provide the highest possible level of function. “Our key to success is a combinatorial strategy, matching promoter variants with target and auxiliary genes to maximize protein output,” Dr. Perkarthofer explained.
The company is in a rather unique situation, in that the technology division was recently formed as a unit of the main company, VTU Holding, which includes engineering and energy-production divisions. This means that there are ample opportunities for collaborative efforts in developing upstream and downstream processes with respect to questions of energy consumption, reactor design, and efficient management of a scale-up program.
Nothing succeeds like overexpression, as the mammalian-cell protein-expression platforms has so dramatically proven. As scientists, program managers, and regulators have become increasingly more comfortable with mammalian-cell expression programs over the years, it has become virtually impossible to dislodge them from their pinnacle. Nonetheless, alternatives keep appearing, and many have received widespread endorsement.