Enhanced Version of Existing CRISPR based Technology

Context

Recently scientists have developed an enhanced genome-editing system that can modify DNA more precisely and efficiently than existing CRISPR-based technologies.

About

• The CRISPR-Cas system is a tool to cut, delete, or add DNA sequences at precise locations, establishing distinctive windows to treat genetic problems, expand drought-resistant flora, and modify food crops.
• CRISPR takes place naturally in a few bacteria, as a part of their immune system that limits infections by recognising and destroying viral DNA.

CRISPR-Cas9

• Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR) is a DNA sequence which is a part of the bacterial protection machine.
• Cas9 (CRISPR-related) is the name of the protein that transfers resistance.
• It is an enzyme that acts like a couple of molecular scissors, capable of cutting strands of DNA.
• It permits researchers to easily alter DNA sequences and modify gene function.
• CRISPR-based tools rely on the capability of the system to comprehend particular single-nucleotide adjustments in the DNA. 

How does the CRISPR-Cas9 work?

• The CRISPR-Cas9 gene modifying tool makes use of a guide-RNA (gRNA) designed to locate and bind to a specific part of the target genome. 
• The gRNA directs an enzyme, Cas9, to the goal website online, that is followed by a quick DNA series referred to as protospacer adjoining motif (PAM). 
• Cas9 recognises and binds to the PAM sequence, and acts as a molecular scissor that snips a few broken DNA. 
• This automatically triggers the mobile’s DNA repair gadget, which maintains the snipped part to insert the proper DNA sequence.

CRISPR’s off-target problem

• The CRISPR-Cas9 system can also realise and reduce elements of the genome aside from the supposed element. 
• Such “off-goal” outcomes are more commonplace whilst the use of the SpCas9 enzyme derived from Streptococcus pyogenes bacteria. 
• To triumph over those troubles, researchers are exploring especially particular Cas9 enzymes from Francisella novicida bacteria called FnCas9.

Switching SpCas9 with FnCas9

• The scientist has engineered new variations of FnCas9 to decorate it without compromising its specificity.
• An improved FnCas9-based diagnostic may want to target almost twice the range of modifications in comparison to FnCas9, increasing the scope of detecting greater disease-inflicting genetic changes.
• Hence the improved FnCas9 cuts target DNA at a higher rate in comparison to unmodified FnCas9.

Source: The Hindu