Creating a Semi-Synthetic Organism

All organisms share a genetic language: four nucleotides that make up the genomes of all known life. A, C, T, and G; combinations of these four base pairs have clearly led to a massive variety of living things. With this in mind, Professor Floyd Romesberg and graduate student Yorke Zhang’s synthetically created organism is even more amazing. This strand of E. coli, containing synthetic base pairs X and Y in its genome, is a groundbreaking discovery and could lead to many beneficial applications in medicine and other fields of science.

These scientists at The Scripps Research Institute began the study in 2014, and just recently announced the results: “a new bacterium that uses the four natural bases (called A, T, C and G), which every living organism possesses, but that also holds as a pair two synthetic bases called X and Y in its genetic code”. How did they do this? The process was long and difficult, to say the least. First, the researchers created two synthetic base pairs (X and Y), small molecules of similar makeup as that of the normal nucleotides. The base pairs were not made for a certain purpose, such as providing resistance to a drug or something that would benefit the organism, but instead to see if a single-celled organism could retain the new bases and continue to function and reproduce. Romesberg and Zhang were able to insert the synthetic nucleotides into the genome of an E. coli bacterium, but it when it divided it did not pass on the base pairs consistently. To solve this problem, the researchers thought about how bacteria and viruses interact. A bacterium fights off a foreign invader by taking some of the enemy genome and putting it in their own genome. This acts as a ‘wanted poster’ so the organism knows to attack that virus if it encounters it again. Taking this information, the scientists used CRISPR-Cas9, (a popular tool in human genome experiments) to make an organism without the synthetic X and Y pairs to be seen as an enemy. In this way, organisms would need to HAVE those base pairs to survive. By making them necessary for life, the scientists succeeded in making the E. coli pass down the new nucleotides. After 60 rounds of replication, the bacteria retained the X and Y bases, making the researchers confident that the organisms could keep the synthetic nucleotides in their genome infinitesimally.

So how does this apply? While the scientists concluded that their are “zero applications as of now,” I think that there are many possibilities for how this newfound knowledge could benefit society. If the base pairs could be arranged in a specific way to code for a new protein that the original base pairs were not capable of, then this new protein could help people fight off other kinds of diseases. Or bacteria could have a genome that allowed them to digest the waste in landfills. Or they could digest chemicals in the air that have a negative effect on the environment and release oxygen or carbon dioxide. Creating synthetic base pairs for specific purposes could lead to literally endless possibilities. Organisms that could survive in space, or make space colonies more efficient by producing useful chemicals for human life. In the end, this study is the first of many huge discoveries in synthetic genome studies, and I am excited to see or take part in more of these discoveries.

About Mr. Mohn

Biology Teacher

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