Discovery of a better gene-editing tool?

Shrayana Ghosh, Amity University Kolkata

According to a new study by UC San Francisco scientists, gene editing for the generation of different treatments and the study of disease and normal function in humans and other organisms may develop more rapidly with a new tool for cutting larger pieces of DNA out of the genome of a cell.

CRISPR, which was recently selected to receive the Nobel Prize in chemistry, evolved ages ago in Bacteria as a way to battle against a host of viruses referred to as Bacteriophages and now is being used as a research tool in laboratories.

On encountering a bacteriophage, the bacteria incorporate a part of the phage’s genetic material into its own as a ‘memory’. The phage’s DNA is copied into small molecules known as CRISPR RNAs, which on combining with one r more Cas proteins form a Cas complex. The CRISPR RNA serves as a template for recognition and any match found is targeted, disabled and killed by the CRISPR proteins.

Joseph Bondy-Denomy, an associate professor from the Department of Microbiology and Immunology, UCSF accompanied by  Bálint Csörg and Lina León developed and tested the new CRISPR-Cas3 system which utilised a discrete bacterial immune system which acted like a “molecular wood chipper” and could cut and remove longer parts of DNA with more accuracy in a shorter period different from the CRISPR-Cas9 which cuts a smaller piece of DNA at the target site.

This characteristic feature of CRISPR Cas9 to delete and replace longer parts of DNA can more efficiently help the scientists to analyse the genomic region of the DNA containing unknown sequences giving them an in-depth understanding of the pathogens and how they affect humans, thus providing an easy way to remove potential pathogens or useless DNA from cells. CRISPR-Cas3 can also be used in biotechnology industries such as agriculture and human gene therapy as it allows the insertion of the entire gene into the genome. Unlike CRISPR-Cas9, CRISPR-Cas3 on binding with the target DNA begins chewing one of the strands in the double-stranded DNA in both directions, leaving a single strand exposed and in DNA repair CRISPR-Cas3 allows the researcher to precisely set the boundaries for repair in the large DNAs.

Also read: F. occidentalis: An Genomic-Insight Into The Crop Pest

Sources-

1. https://www.news-medical.net/news/20201021/New-DNA-cutting-tool-could-advance-gene-editing-for-novel-treatments.aspx
2. https://www.nature.com/articles/s41467-019-13226-x

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