Friday, June 4th, 2021 -- For the very first time, scientists from the Medical Research Council (MRC) Laboratory of Molecular Biology in Cambridge, UK have developed special (bacteria) cells that are able to construct artificial polymers, from building blocks (monomers, coded by codons) that are not present in nature. In order for researchers to make this possible, they encoded specific instructions in the genes of the bacteria. Through this study, the scientists also discovered that this synthetic (artificial) genome also made the bacteria resistant to viral infection.
Prior to this study, in 2019, the MRC research team used biotechnology techniques to construct the complete genome of the bacterium E.coli (Escherichia coli) in a lab. In doing so, they also simplified the genome by replacing some of its codons so that it has a different sequence while still coding for the same amino acid. This modified bacteria no longer contained those replaced codons in their genome, but they could still make normal proteins and live and grow.
Building on this study, the scientists have further altered the bacteria to remove the tRNA molecules that recognized those removed/replaced codons. This means that even if those codons are present in the genome, the cell would no longer be able to read those codons.
Since virus genomes contain high quantities of these replaced/removed codons, any time a virus tries to enter the bacteria, it is immediately destroyed since the modified bacteria has no mechanisms to read the virus genome.
The creation of these virus-resistant bacteria could lead to the development of new polymers, such as proteins, plastics, and many drugs. Since even a trace of a virus in a batch of drug-manufacturing bacteria could destroy the whole batch, these modified bacteria could make manufacturing certain types of drugs (antibiotics, insulin, etc.) much more reliable and cheaper.
In the creation of these synthetic bacteria genomes that do not contain certain codons, the researchers have allowed these codons to be used for other purposes, like coding for monomers (synthetic building blocks). According to study lead, Professor Jason Chin from the MRC Laboratory of Molecular Biology, "These bacteria may be turned into renewable and programmable factories that produce a wide range of new molecules with novel properties, which could have benefits for biotechnology and medicine.” Professor Chin also mentioned that he and his team plan to “investigate applications of this technology to develop novel polymers, such as biodegradable plastics, which could contribute to a circular bioeconomy.”
Source: (2021) First cells reprogrammed to make synthetic polymers. In: UKRI. https://www.ukri.org/news/first-cells-reprogrammed-to-make-synthetic-polymers/. Accessed 4 Jun 2021
Polymers: substances that are made up of large molecules, called macromolecules, of smaller, repeating chemical units
Genome: all the genetic material of an organism, consisting of various types of DNA
Codons: a group of three mRNA bases (Adenine, Cytosine, Uracil, Guanine) that is read by special molecules called “tRNA,” which brings the corresponding amino acid to the ribosome to continue the protein-making process. There are also codons (“Stop Codons”) that indicate the cell to stop making the polypeptide/amino acid chain.