Anannya Roy, Amity University Kolkata
CRISPR- Cas 9 gene-editing system, we all have heard of that isn’t it? A giant in Gene editing. Well here’s the thing- There is something even more interesting than that.
Retrons: A group of researchers at Harvard University and Harvard Medical School have created a new gene-editing tool called Retron Library Recombineering (RLR). This technology is much more useful than CRISPR Cas9 in the field of synthetic biology. CRISPR Cas9 can be beautifully programmed to find and cut specific pieces of DNA but it has certain limitations. The process of editing the DNA to create desired mutations involves manipulating the cell into using a new piece of DNA to repair the break. This procedure is pretty complicated and might even be toxic to cells as it can cut off non-target sites. Other gene-editing techniques involve creating genetic mutations by inserting alternate pieces of DNA while the genome replication is going on. But this procedure is time-consuming.
Retron Library Recombineering is different from the other methods because it can generate millions of mutations and screen them, ultimately massive amounts of data are easily generated and analyzed. The current research was done on the bacterial genome, which was chopped up and turned into single-stranded fragments of DNA. According to one of the scientists, this gene-editing tool is incredibly flexible and can be used for various experiments. The chances of toxicity to cells are also null. Retrons are mainly segments of bacterial DNA that undergo the process of reverse transcription and produce single-stranded DNAs. The procedure involves integrating a single-stranded DNA with the desired mutation into the host organism’s DNA and there are two ways to perform this. In the first technique, the mutant sequence is inserted after the double-stranded DNA is cut physically using CRISPR-cas9 or any other technique. The other method involves inserting mutant DNA and Single-stranded annealing protein into a replicating cell thus incorporating them into the genome. What I think, makes this technology remarkable is that they can identify which of the bacteria have received a retron sequence and which haven’t, thus serving as “Barcodes”.
During the experiment, antibiotic resistance genes were put in circular plasmids of bacterial DNA and they were placed along with retron sequences and the SSAP gene, which helped in the integration into the bacterial genome. Only 0.1% of the Ecoli cells displayed the desired mutation. After several attempts and using different techniques, the number increased to 90%.
This new tool is currently a trending topic and is causing a lot of excitement among researchers and genetic engineers. It is very promising and is said to answer any questions we have regarding how multiple mutations interact with each other and the effects they cause in the organism’s body. Today in our modern ever-changing world, Retrons are something out of a Science Fiction novel. There is a lot to hope for in the future of Biotechnology.
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