Why in news
Researchers have developed a plant genome editor consisting of a protein derived from Deinococcus radiodurans bacteria — famous for being able to survive extreme conditions.
The protein is less than half the size of the proteins CRISPR commonly uses to target specific parts of the DNA
Deinococcus radiodurans
It is a type of bacteria known for its extraordinary resistance to extreme conditions, including high levels of radiation, desiccation, and various chemicals.
Its resilience is due to its highly efficient DNA repair mechanisms that allow it to recover from severe damage.
Applications: Its unique properties are studied for potential applications in biotechnology, including bioremediation and radiation protection
CRISPR gene-editing tool
CRISPR (Clustered Regularly Interspaced Short Palindromic Repeats) is a powerful tool used to make precise changes to the DNA of organisms
It uses guide RNA to direct the Cas9 or Cas12 protein to a specific DNA sequence where it makes cuts or modifications.
Widely used in genetic research, medicine, and agriculture to edit genes, improve crops, and potentially treat genetic disorders
But they are too bulky for plant cells to accommodate.
It usually involves the introduction of a new gene, or suppression of an existing gene, through a process described as genetic engineering.
CRISPR technology does not involve the introduction of any new gene from the outside.
CRISPR-Cas9 technology is often described as ‘Genetic Scissors’.
Its mechanism is often compared to the ‘cut-copy-paste’, or ‘find-replace’ functionalities in common computer programmes
A bad stretch in the DNA sequence, which is the cause of disease or disorder, is located, cut, and removed and then replaced with a ‘correct’ sequence.
The tools used to achieve this are biochemical i.e., specific protein and RNA molecules.
The technology replicates a natural defence mechanism in some bacteria that uses a similar method to protect itself from virus attacks.
Mechanism:
The first task is to identify the particular sequence of genes that is the cause of the trouble.
Once that is done, an RNA molecule is programmed to locate this sequence on the DNA strand
After this Cas9 is used to break the DNA strand at specific points, and remove the bad sequence.
A DNA strand, when broken, has a natural tendency to re-attach and heal itself. But if the auto-repair mechanism is allowed to continue, the bad sequence can regrow.
So, scientists intervene during the auto-repair process by supplying the correct sequence of genetic codes, which attaches to the broken DNA strand.
The entire process is programmable, and has remarkable efficiency, though the chances of error are not entirely ruled out.
Limitations
CRISPR-Cas9 system can also recognise and cut parts of the genome other than the intended portion.
Such “off-target” effects are more common when using the SpCas9 enzyme derived from Streptococcus pyogenes bacteria.
Scientists have been able to engineer versions of SpCas9 with higher fidelity but only at the cost of editing efficiency
TnpB Based Editing Tool
TnpB is a protein derived from Deinococcus radiodurans used for genome editing.
Unlike CRISPR, TnpB targets and edits DNA using its own mechanism, which is smaller and potentially more suitable for plant cells.
Smaller size compared to CRISPR systems, which makes it more suitable for editing plant genomes where space is limited
ISDra2TnpB
ISDra2TnpB is a specific version of the TnpB protein used for genome editing.
Derived from Deinococcus radiodurans, it is optimized for use in plant genome editing.
ISDra2TnpB is less than half the size of Cas9 and Cas12.
Future of Edited Plants
Edited plants using tools like ISDra2TnpB could lead to significant improvements in crop traits, such as increased yield, disease resistance, and stress tolerance.
Potential applications include :
creating crops with enhanced nutritional profiles,
reduced anti-nutrient factors,
better resilience to environmental challenges
Challenges:
Further development and testing are needed to improve efficiency and effectiveness across different plant species
ensure successful integration of edited traits into commercial crops.
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