
Alternative to CRISPR/Cas9 – CAST (CRISPR-associated transposase) – A New Gene-editing Approach for Insertion of Large DNA Sequences into a Genome developed @BroadInstitute @MIT @Harvard
Reporter: Aviva Lev-Ari, PhD, RN
A new gene-editing CAST member
In Science, a team led by Jonathan Strecker, Alim Ladha, and core institute member Feng Zhang reports a new gene-editing approach that can precisely and efficiently insert large DNA sequences into a genome. The system, called CRISPR-associated transposase (CAST), is a completely new platform to integrate genetic sequences into cellular DNA, addressing a long-sought goal for precision gene editing. The team molecularly characterized and harnessed the natural CAST system from cyanobacteria, also unveiling a new way that some CRISPR-associated systems perform in nature: not to protect bacteria from viruses, but to facilitate the spread of transposon DNA. Check out more in coverage from STAT and New Scientist.
SOURCE
https://www.broadinstitute.org/news/research-roundup-june-7-2019
Abstract
CRISPR-Cas nucleases are powerful tools to manipulate nucleic acids; however, targeted insertion of DNA remains a challenge as it requires host cell repair machinery. Here we characterize a CRISPR-associated transposase (CAST) from cyanobacteria Scytonema hofmanni which consists of Tn7-like transposase subunits and the type V-K CRISPR effector (Cas12k). ShCAST catalyzes RNA-guided DNA transposition by unidirectionally inserting segments of DNA 60-66 bp downstream of the protospacer. ShCAST integrates DNA into unique sites in the E. coli genome with frequencies of up to 80% without positive selection. This work expands our understanding of the functional diversity of CRISPR-Cas systems and establishes a paradigm for precision DNA insertion.
SOURCE
https://science.sciencemag.org/content/early/2019/06/05/science.aax9181
Other related articel published in thies Open Access Online Scientific Journal, include:
Breakthrough in Gene Editing CRISPR–Cas systems: First example of a fully programmable, RNA-guided integrase and lays the foundation for genomic manipulations that obviate the requirements for double-strand breaks and homology-directed repair.
Reporter: Aviva Lev-Ari, PhD, RN
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