Breaking down the CRISPR-Cas mechanism

Researchers Guillermo Montoya, Pablo Alcón and Stefano Stella from Novo Nordisk Foundation Center for Protein Research compile, compare and discuss the molecular characteristics of the CRISPR-Cas tools used for genome editing, in an article in Nature Structural and Molecular Biology (2017-10-16).

This article compiles and compares the basic characteristics of the CRISPR-Cas Class2 proteins in depth and for the first time collects all structural and mechanistic information available for these proteins.

The instructions required to build and maintain all life on Earth are contained in DNA molecules present in our cells. Just like a misspelt word can affect the meaning of a sentence, an error in the DNA can lead to mistakes in the instructions and in cell defects. We know that this is how genetic diseases occur and why don’t we try to correct these mistakes? The idea of correcting DNA errors has become reality in recent years through the development of genome editing techniques where DNA is inserted, deleted or replaced in a living organism. The technology has had tremendous impact on biological research.

In order to initiate editing at a certain position in the genome, a very precise cleavage of the DNA molecule must be made. To achieve this, researchers use “molecular scissors”, proteins that are able to cut DNA. The revolution of genome editing came with the development of the versatile CRISPR-Cas guided systems where custom-made RNA molecules escort the molecular scissors (the protein) to the correct position in the DNA molecule. The possibility to redesign these molecular DNA scissors to find and cut a specific sequence of the genome in other organisms than bacteria, including humans, has transformed them into the ideal genome editing tools.

In this article, researchers at Novo Nordisk Foundation Center for Protein Research at University of Copenhagen compare how the members of the Class 2 CRISPR-Cas proteins recognize a target DNA sequence to promote the precise cut that initiates the editing process. Further understanding of the similarities and differences between these proteins is essential not only to optimize their accuracy as genome editing tools. The mechanistic insights discussed here are also crucial to expand the landscape of possible applications of these proteins, ranging from therapeutics to biotechnology and synthetic biology.

Authors: Pablo Alcón Hernández, Stefano Stella and Guillermo Montoya

Link to full article in Nature Structural & Molecular Biology: Class 2 CRISPR–Cas RNA-guided endonucleases: Swiss Army knives of genome editing