Plug and Play with DNA Constructs

DNA production is becoming cheaper than ever, propelled down a Moores law curve by maturing technologies and cheaper reagents. This new biosynthetic industry allows researchers to order up a customized sequence for overnight delivery.

But many users dont just want a chain of nucleotides, they want ready-to-use sequences that can be inserted into a cell to make a product of interest. Such DNA products, known as constructs, include two components a vector that will be read by host machinery and initiate transcription, and an inserted gene that will generate the non-native biomolecule. Constructs can be thousands of bases in length, but once theyre uploaded to the cell, production should be good to go.

This niche is where Genscript is staking its claim. Were the worlds largest provider for construct based gene synthesis, says Jeffrey Hung, a Genscript Vice President, and a lot of our growth is coming from higher demand for biologics, or medicinal biomolecules generated through a microbial host (as opposed to an exclusively chemical synthetic process). Most frequently, the company takes orders for non-native products to be expressed in a different organism, turning the unwitting target cell into a biofactory for recombinant proteins or antibodies. In many cases, biologics the result of intentional expression of known biomolecules are safer than uncharacterized but empirically promising small molecules taken from a cellular milieu. And using the cell as a production platform is an appealing prospect: organisms can tune behavior and metabolism to changing conditions, so small fluctuations in temperature or reactant concentration wont doom a costly industrial process.

For example, in an effort to identify antibodies best suited to recognize potentially threatening pathogens, a range of recombinant antibodies can be produced in a host cell. Tracking how well the displayed pathogenic molecule is bound by different antibodies can identify promising new treatment options. And once that lead is found, explains Hung, we can improve upon it by making the affinity better and better, through iterative design modifications. This sort of approach is becoming increasingly prevalent in immunological fields, including immuno-oncology and autoimmune disease research.

Genscript has also generated a platform for yeast genetics that can quickly narrow the search for case-specific essential genetic components. Its called SC 2.0, and it starts by creating mutations in each of the organisms 6,000 genes. The resulting mutants are grown in isolated wells and monitored for growth. If nothing happens, then youve mutated an essential gene; if the media turns cloudy with cells, then youve identified a non-essential component. We can ask the simple question, says Hung, of which genes are specifically more important for responding to certain environments given certain environmental stimuli. This way, experimenters can separate housekeeping genes from those needed for higher temperature growth, or increased biofuel production. Understanding which aspects of the wild type yeast lifestyle are superfluous under industrial settings highlights opportunities to trim the fat and ensure that the biologically mediated process youre after is as efficient as possible.

Weve found that about 25% of the yeast genome is essential, says Hung, and that 75% is where a lot of future discoveries remain to be found.

*This article is part of a special series on DNA synthesis and was previously published at SynBioBeta, the activity hub for the synthetic biology industry.

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Plug and Play with DNA Constructs