A semi-synthetic life.
Researchers at the Scripps Research Institute in California have become the first to create a whole new form of life, one with six letters to its genetic code instead of four. They say the results will pave the way for the creation of “organisms with wholly unnatural attributes and traits not found elsewhere in nature.”
For as long as there has been life on Earth, the building blocks used to create the bounty of life forms we see around us have been constant and unchangeable. Nature has used the same four nucleotide bases -adenine, cytosine, guanine and thymine- molecules that link up in pairs to form the rungs of the DNA ladder, to produce an infinite variety of organisms. Now, with the help of new research techniques such as the gene editing tool CRISPR-Cas9, scientists have created stable “semisynthetic” life which uses not only A, C, G and T for its DNA base pairs but also a couple of synthetic molecules that researchers call X and Y.
Semi-synthetic life will “blow open what we can do with proteins…”
“This will blow open what we can do with proteins,” says Floyd Romesberg of the Department of Chemistry at the Scripps Research Institute and lead author of the new study, to The Guardian.
Back in 2014, Romesberg and his team first announced the creation of a modified version of E. coli bacteria, one which held the expanded genetic code. Their new creation proved to be unstable, however, and unable to keep the extra base pairs indefinitely, a result which Romesberg equates to discovering electricity but not being able to keep the light on. “Your genome isn’t just stable for a day,” said Romesberg in a statement. “Your genome has to be stable for the scale of your lifetime. If the semisynthetic organism is going to really be an organism, it has to be able to stably maintain that information.”
The breakthrough came with the use of CRISPR-Cas9, itself a DNA segment coupled with an enzyme, to alter the semi-synthetic E. coli so that it would refrain from treating cells containing X and Y molecules as foreign invaders, allowing them to proliferate. “The optimized semi-synthetic organism (SSO) grows robustly,” say the study’s authors, whose research is published in the journal Proceedings of the National Academy of Sciences. “This SSO is thus a form of life that can stably store genetic information using a six-letter, three-base-pair alphabet.”
Romesberg sees his research as geared towards the creation of new proteins not found in nature, with the aim of making new drugs to fight disease. As far as the worry about ‘playing God’ and perhaps unleashing uncontrollable processes into the environment, Romesberg is steadfast in his belief that we cannot be afraid of the unknown, saying, “the benefits need to be weighed against the potential costs, and in this case the benefits include new and better drugs.”
DNA research has come a long way since the double helix was first discovered in 1953 by James Watson and Francis Crick. The mapping of the human genome was finished in 2003, giving scientists a complete record of the sequencing of base pairs within human DNA, a feat which has subsequently been repeated for a number of other complex organisms.
This year, to mark Canada’s 150 anniversary, geneticists at Toronto’s Hospital for Sick Children have sequenced the genome of the Canadian beaver. “The Canadian beaver had not been done, and we figured if anyone’s going to do the Canadian beaver, it should be Canadian scientists,” said Stephen Scherer, director of the hospital’s Centre for Applied Genomics. The team used the DNA from a 10-year old male beaver from the Toronto Zoo.