TALEN genome editing tool outperforms CRISPR-Cas9 by 5 times

Fragile X syndrome, sickle cell anemia, beta thalassemia and other diseases are

result of genetic defectsheterochromatin. After conducting the study, scientists came to the conclusion that in such densely packed parts of the genome, the TALEN editing tool is more effective than traditional CRISPR/Cas9. Biologists report their findings in the journalNature Communications.

According to Humin Zhao, professor of chemical andin biomolecular engineering from the University of Illinois at Urbana-Champaign, who led the new study, the discovery confirms that a wider range of genome editing tools is needed to cover all parts of the genome.

“CRISPR is a very powerful tool that revolutionized genetic engineering,” Zhao explains. "But he still has some limitations."

Zhao and his colleagues used fluorescentsingle molecule microscopy to directly observe how two genome editing tools work in living mammalian cells. The fluorescent tags allowed researchers to measure how long it took for CRISPR and TALEN to move along the DNA, as well as detect and cut out target regions.

“We found that CRISPR works betterin less vulnerable regions of the genome, but TALEN can access these genes in the heterochromatic region better than CRISPR, Zhao said. “We also saw that TALEN could have higher editing efficiency than CRISPR.” It can cut DNA and then make changes more efficiently."

In total, TALEN was five timesmore effective than CRISPR in multiple experiments. In any case, the results will lead to improved approaches to targeting different parts of the genome, Zhao concludes: "Either we can use TALEN for certain applications, or we can try to improve CRISPR performance with heterochromatin."

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University of Illinois at Urbana-Champaign, UIUC- the largest of the campuses of the University of Illinois. Founded in 1867. Located in the merged cities of Urbana and Champaign in the center of Illinois, USA.

Heterochromatin - areas of chromatin that are in a condensed (compact) state during the cell cycle. A feature of heterochromatic DNA is its extremely low transcribability.

Activator-like effector nucleasesTranscription activator-like effector nucleases, TALENs, are restriction enzymes that can be engineered to cut specific DNA sequences.

CRISPR - special loci of bacteria and archaea,consisting of straight repeating sequences separated by unique sequences. Spacers are borrowed from foreign genetic elements that the cell has encountered.

Cas9 (CRISPR associated protein 9,CRISPR-associated protein) is a guide RNA-controlled endonuclease associated with the adaptive immune system CRISPR (Clustered Regularly Interspaced Palindromic Repeats) in a number of bacteria, in particularStreptococcus pyogenes.S. pyogenesuses Cas9 to store, inspect, and cut foreign DNA, such as bacteriophage or plasmid DNA.