NEXT GENERATION GENOME EDITING TECHNOLOGIES Next-Generation-Genome-Editing-Technologies | Page 12
The synthesis of crRNA is economically cost effective because when one uses Cpf1 guide
RNAs they have to work upon only 42 nucleotides. Whereas in CAS9 cost of 100 nucleotides
has to be bared as it is a hybrid of (crRNA/trRNA).
It is easier to deliver them as their size is small. Low capacity vectors can be used like adeno-
associated viral vectors.
‘Second chance mechanism’ can be carried out as PAM sites are not destroyed during
cleavage. This is because they are located 18-20 bp away. So a second HDR edit can be made.
2. NgAgo: The experimental child
Gene editing has never been so interesting like it is being right now. While CRISPR is making
scientist gaga over its abilities, there has been a new development to its genre. NgAgo, a DNA
cleaving argonaute from Natronobacterium gregoryi, plays an essential role in eukaryotes during
RNA interference. It binds guideRNA to cleave foreign DNA. They are also present in prokaryotes
and help them protect against foreign DNA. The orthologs like NgAgo which are thermophilic
in nature can cut plasmid and genomic DNA in mammalian cell lines. It can also mediate HDR,
when a template is supplied.
Cpf1 CAS9 NgAgo
Endonuclease Lacks HNH Has HNH domain Argonaute protein
Requires only one guide Requires trRNA as well as Requires guide DNA
RNA crRNA Produces sticky end Produces blunt end Base removal technique
PAM sites are not destroyed PAM sites destroyed PAM sites are not destroyed
Easier to deliver, low Low capacity vectors cannot Low capacity vectors cannot
capacity vectors can be used be used be used
domain