Sam Sternberg, PhD
Columbia University

Presenting: Transposon-encoded CRISPR-Cas systems direct RNA-guided DNA integration

Conventional CRISPR–Cas systems maintain genomic integrity by leveraging guide RNAs for the nuclease-dependent degradation of mobile genetic elements, including plasmids and viruses. Here we describe a remarkable inversion of this paradigm, in which bacterial Tn7-like transposons have coopted nuclease-deficient I-F CRISPR–Cas systems to catalyze RNA-guided integration of mobile genetic elements into the genome. Programmable transposition of Vibrio cholerae Tn6677 in E. coli requires CRISPR-and transposon-associated molecular machineries, including a novel co-complex between Cascade and the transposition protein TniQ. Donor DNA integration occurs in one of two possible orientations at a fixed distance downstream of target DNA sequences, and can accommodate variable length genetic payloads. Deep sequencing experiments reveal highly specific, genome-wide DNA integration across dozens of unique target sites. The discovery of a fully programmable, RNA-guided integrase lays the foundation for genomic manipulations that obviate the requirements for DNA double-strand breaks and homology-directed repair.

All-division colloquium.

Hosted by Jason Peters