Researchers at Massachusetts Institute of Technology developed a revolutionary new gene editing tool. The tool is called PASTE, and it is a new CRISPR-Cas9 based genome editing tool. It combines traditional CRISPR and integrases, enzymes that can insert or remove DNA sequences, to cut out certain DNA segments and “paste” in other DNA segments. This new method removes the necessity for double-stranded DNA breaks, which can lead to mutations in the DNA sequence. 
PASTE combines CRISPR-Cas9 nickase, which cuts out a singular DNA strand, with serine integrase, an enzyme that can insert a lot of DNA, and reverse transcriptase, an enzyme that allows PASTE to add a single strand of DNA each time while preventing double-stranded DNA breaks. PASTE produces less indels than CRISPR-Cas9 alone. Indels(insertions or deletions are genetic mutations that often occur when a gene is edited. They can alter the function of genes, thus affecting the organism’s overall health or specific traits (New Atlas).
Additionally, PASTE researchers believe that PASTE could possibly treat genetic diseases by replacing “bad” genes with “good” genes. This is because PASTE is great at “pasting” genes into various parts of an organism’s genome. PASTE researchers tested PASTE against homology-independent targeted insertion and homology-directed repair, discovering that paste had higher insertion effectiveness than homology-independent target insertion, but lower insertion effectiveness than homology-directed repair. PASTE, however, produced less “inaccuracies” than homology-directed repair. These inaccuracies occur when the tool inserts DNA into the wrong part of an organism’s genome, effectively risking unwanted effects (Genome Web).
While PASTE is still in its infancy, it is already revolutionizing the gene editing industry. It not only reduces the risk of undesired mutations, but also increases the efficiency of gene insertion. It is pioneering treatment of genetic diseases.
AP Bio Side Note 🙂
This technology relates to AP Bio because of its use of introns and exons. PASTE can remove or replace introns and exons, depending on what causes the genetic mutation. This is interesting because although introns are noncoding sequences of DNA, mutations in them can still cause negative effects in people. Additionally, while more intuitive, it is also revolutionary that technology is able to replace exons. I am excited to see what the future for Crispr tools holds. Please leave a comment if you found this post interesting!
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