A synthetic genetic code

Although a large part of how our body works still remains to be known, certain functions have been detailed and understood for years. Like the genetic code – no longer a mystery right? Wrong. New research by Cambridge scientist Jason Chin will change our ideas about our “genetic code” forever.

First some basic information on the genetic code. George Gamow first postulated a theory on how it worked after the discovery of the DNA double helix by Watson and Crick which turned out to be right. As is well known, DNA is made up of a double strand on long molecules made from 4 nucleotides (A,T,C and G) which match up in pairs – A-T and C-G – to create the double helix. The genetic code is defined as the set of rules followed by cells to translate DNA (and other genetic materials) into the proteins which make up the forms and functions of our living bodies. A process called transcription creates a molecule from DNA called messenger RNA which is an exact copy on one strand of DNA. The only difference is that T nucleotides are replaced by U nucleotides to make a further distinction between DNA and mRNA. Following this translation occurs in which a large protein called a ribosome travels along mRNA, reads the code and translates it into amino acids (a series of amino acid makes a polypeptide also known as a protein). The way the ribosome reads mRNA is via a series of nucleotide triplets each corresponding to a known amino acid. For instance, AUG codes of amino acid methionine and ACG for serine. A total of 64 “recurring” combinations codes for 20 different amino acids.

So what is so special about the new research being undertook? Jason Chin and his laboratory have in a sense re-invented the genetic code. They have created a whole new reading system which reads the mRNA by quadruplets of nucleotides as opposed to triplets. By adding chemical groups to normal amino acids and creating novel ribosomes and tRNA molecules (also used in the translation process, these molecules recognised a triplet and match it with the corresponding amino acid), they were able to redesign cells’ machinery. Using the same basic translation process as in normal cells, they are able to create over 276 new synthetic amino acids through a series of new combinations.

But what those this mean and what is the point? Firstly, the idea of creating new amino acids is significant from a medical point of view. Proteins formed from the basic 20 amino acids need a certain environment to remain in the fold that makes them functional. Simple things such as temperature and acidity can change their structure making them useless and sometimes even toxic. Because Chin’s amino acids form links in different ways to normal ones, the structure of the formed proteins are much more stable and can thus withstand much harsher conditions. Such as the high acidity levels found in the digestive tract. It will be possible to create medicine that will not be destroyed directly in the stomach and have a better chance of reaching the targeted area. Experiments with a protein extensively found in the body, Calmodulin, has proved successful. Modulating the amino acids to form this protein lead to the formation of a synthetic version of Calmodulin with altered resistance. Creation of synthetic compounds could also make pharmaceutical products cheaper as Chin’s synthetic proteins can be gown up in bacteria, a simple and cheap process rather than the expensive procedure used nowadays.

Although these findings could mean a whole new world of genetics, some scientists do worry that it might interfere with other processes in the body. By only modulating some proteins, could the consequences be disastrous in normal bodies? Could we create life built only on this synthetic code? Research is only at in its starting blocks, but this is one to watch.


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About me

Natacha is a research scientist and a lover of all things science! She love finding out interesting facts about all aspects of life, whether it’s how genetic engineering works or what the difference between crimped and straight hair is. There’s a bit of science behind every mystery and the Science Informant will help find the clues for everyone to enjoy and understand the amazing world of science!

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