Clustered regularly interspaced short palindromic repeats, shortened as CRISPR, is the most talked about advancement in the field of genetic engineering (or genome engineering) these days. So, what is the buzz about? In this post, the aim is to discuss the seminal works briefly and where CRISPR would find its application.
The years between 1993 and 2005 can be recognized as the discovery phase of CRISPR. Francisco Mojica had been working on the locus (disparate repeat sequences) for almost two decades which is now the hallmarks of CRISPR sequences. The term CRISPR was jointly coined by Ruud Jansen and Francisco Mojica.
In May 2005, Alexander Bolotin of French National Institute for Agricultural Research (INRA) studying Streptococcus thermophiles discovered an unusual CRISPR locus, the prime difference being novel CAS genes. One of the CAS genes now known as CAS9 that codes for protein is predicted to have nuclease activity. In addition, the spacers were identical to that of viral genes, also sharing common sequence in the end. This sequence, Protospacer adjacent motif (PAM) is required for target recognition.
A notable contribution came from Luciano Marraffini and Erik Sontheimer of Northwestern University who demonstrated the target molecule is in fact DNA and not RNA. The authors explicitly observed in the paper that the system could be powerful tool when transferred to non-bacterial systems. However, different type of CRISPR system that target RNA was also identified.
The further advancements such as Cas9 ability to cleave target DNA, discovery of tracrRNA for Cas9 system, CRISPR systems’ ability to function heterologously in other species and biochemical characterization of Cas9-mediated cleavage helped scientists to rely on CRISPR as gene editing tool for the future in the world of genome engineering.
CRISPR system is viewed as a viable tool to create molecular pharmacies, destroy viruses such as HIV, Herpes and Hepatitis, CRISPR modified plants to reduce dependence on petrochemicals, precision system to develop new cancer treatments and most importantly study diseases such as like Alzheimer’s and Parkinson’s.
Plant biologists also see CRISPR as a viable system to enhance plant’s ability thereby food security and figure out the functions of genes in complex environments.