- Researchers at the Delhi-based Institute of Genomics and Integrative Biology (CSIR-IGIB) have discovered a protein variant from a different species of bacteria that can edit the DNA with very high precision. In the tool now commonly used for editing disease-causing mutations in DNA (CRISPR-Cas9), the Cas9 protein behaves like a molecular scissors that cuts the DNA at a specific location and inserts a foreign piece of DNA to correct the mutation that causes the disease.
Importance of new protein
- Commonly used Cas9 protein from Strepotococcus pyogenes bacteria (SpCas9) and its engineered derivative tend to potentially bind to DNA at multiple unintended sites thereby leading to unnecessary alterations in the DNA.
- The Cas9 protein is supposed to bind to the DNA only when there is a perfect match between the DNA and the protein, thus reducing the chances of the protein binding at non-target sites on the DNA.
- But even when three mismatches exist between the protein and the DNA, the currently used SpCas9 protein binds and cleaves the DNA.
About FnCas9 (New Cas9 Protein)
- The protein (FnCas9) used by the researchers to edit the DNA is derived from a bacterium — Francisella novicida.
- The researchers found their new Cas9 protein, which binds and cuts the DNA, was able to correct sickle cell anaemia mutation in patient-derived stem cells.
- New FnCas9 protein showed negligible binding when there exists more than one mismatch in the target DNA.
Source: The Hindu