SynBio11: SynBio and XenoBiology (v1.0)

Xenobiology is a new subfield of synthetic biology that may make some people uncomfortable. I will briefly talk about it here. DNA is common to all life on earth. But Xenobiology is biology not based on DNA. It goes beyond the DNA-RNA-20 amino acids life forms. Xeno means alien or foreign. 

Xenobiology has the potential to shed light on our basic understanding of life and why it works. The most fundamental question in biology is how did life really start? Why does life have only one language (DNA) we know of? If life could evolve so soon after the formation of the earth, and was so successful, why did it not emerge multiple times using multiple codes? Is our current code optimal? Could a parallel biology be possible? A biology that exists in parallel with but not compatible with existing creatures? Viruses that exist but do not infect our cells? A biology not even compatible with known lineages? 

Let us take an XNA with an expanded set of letters. XNA is thought to be safer to manipulate because it is incompatible with life. Floyd Romesburg in 2012 expanded the genetic code by two additional letters to create a 6-letter code and defined new complementary base pairs. Romesburg created the first semi synthetic Xeno organism in 2014. In 2017, Romesburg announced that these cells were able to make proteins and therefore he got them to be functional. Are there commercial applications for this? In 2019, a group developed an 8-letter code called Hachimoji DNA (Hachimoji means 8 letters in Japanese). This offers a much larger potential combination of letters!!

But there is a catch. The more letters you introduce, the more novel machinery you must also build to process the novel codes. For example, new enzymes are need, new special growth media are needed, cannot use almost any other existing bio molecules so new ones would be needed. etc. This is not an easy task!! But these proofs of concepts are very intriguing!!

In addition to creating new base pairs, scientists also recoded - changing the number of codons actively coding for amino acids. Codons are three letter words coded to specific amino acids. Sequences of amino acids are the building blocks of proteins which has a huge role in life. Proteins are what gets expressed as a result of genes. Scientists reduced the number of codons and inserted it into an e-coli bacteria (with only 61 of the 64 codons in its protein-coding sequences). It worked. This shows that life's codon design isn't exclusive. This is another proof of concept that is intriguing. 

These experiments and proof of concepts show new designs for life are potentially possible!! The research goes on. It is just at the beginning.