BioCoder #1

Better, CRISPR Homemade Genomes

Derek Jacoby

The point of synthetic biology is editing genomes—adding and removing functionality until the organism you are creating behaves exactly as you want it to. Since this behavior is determined by DNA, these additions and deletions must take place in the genome.

When I was first getting into synthetic biology in 2008, some friends and I formed an iGEM team at the University of Victoria. Everything we worked on was based around BioBricks: biological units of defined functionality. BioBricks contain specific DNA sequences at each end of the DNA so that they can be precisely snipped out with restriction enzymes and then put back together in the order you want them. I remember being amazed at the specificity of restriction enzymes—to be able to cut a piece of DNA at a very precise point confers an amazing ability to move segments of DNA around as functional units and create genetic circuits. However, all the circuits we created had to be on small, circular segments of DNA called plasmids. This introduced some significant limitations: we could only create new circuits, existing functionality in the chromosomal DNA was inaccessible to us, the plasmids had to contain antibiotic resistances, and if we ever placed the new constructs in an environment without that antibiotic selection, our hard-won changes would be gone in just a few generations. So everything we created felt temporary. And it all came about because our palette of restriction enzymes ...