Steve wants to be a biohacker. He has no access to a wet lab but he has done a few molecular biology classes and is up-to-date on the state of the art. He sends away for a kit and 4 to 8 weeks later receives it in the mail. It includes a biohacker device to be connected to his computer and a number of vials of a specially engineered bacteria. After reading the instructions he carefully inserts a vial into the biohacker loads up the software, and inserts a slide. His first creation is the same as most inexperienced biohackers, the test page:
Steve has started on a path that has been paved by a technological revolution that, as I write this, has yet to occur. The development which will take biohacking out of the universities and military labs and into the garage - where all interesting technology must eventually lead - is in vivo DNA synthesis. That is, making any desired DNA sequence directly inside the cell.
For the purposes of this discussion I'm talking about bacterial cells as the vast majority of biohacking today is done using bacteria. But there's no reason why eukaryotic cells cannot be manipulated just as easily and, in fact, proteins that typically occur in eukaryotic cells may be just what is needed to make in vivo DNA synthesis a reality.
I'm specifically thinking about the process of RNA splicing. The most common kind of splicing is cis-splicing where the introns of a single transcript are spliced out, joining together the exons into contiguous mRNA, but there's another kind.
Trans-splicing is the selective joining of two exons that are not within the same transcript. The transcripts are required to share a complementary sequence which causes the two transcripts to line up. The introns are removed as usual.
So it seems that by selective expression of two genes containing appropriate complementary sequences and the required indicators to initiate trans-splicing, a level of mRNA synthesis can be achieved. Imagine a library of "left" and "right" exons of five bases length. This is a total of 2 x 5 x 4 = 40 genes. If each of these genes is promoted by an addressable external signal, we can make 400 different mRNA sequences of 10 bases length on command.
Reverse transcriptase can be used to convert the mRNA back into DNA.
But it would appear we can do even more than this. Once trans-splicing has joined a left to a right exon, there's no reason why complementary sequences on the right exon can not be used to initiate trans-splicing of another transcript. Perhaps we will require another library of five base length exons with appropriate complementary sequences, call them right-right-exons, but we definitely won't need any right-right-right-exons as once we can make reasonably long sequences on command we can encode the appropriate complementary sequence. Now the only limitation is the trans-splicing mechanism - of which k-base-long splices have been reported.
Unfortunately, creation of a "bootstrap" bacteria for a biohacker device will require the
use of a wet lab to create. I, currently, am not in the business of biology, and I'm not
eligible to participate in the iGEM competition as I have been out of school for quite some
time now. If you are interested in this idea and would like to try it out, I would love to
hear your results. Similarly, if you are unimpressed by this idea, or think you have heard
it before, drop me a line.