Cut-and-paste, but not cut, then paste

Genome engineering is constantly searching for new and promising molecular tools – and CRISPR-associated transposons (CASTs) are among them. A new study in Nature Communications from the Querques lab, with Mateusz Walter as a co-first author, reveals how CASTs precisely control DNA transposition. Combining cryo-EM with biochemistry, the researchers uncovered a series of molecular checkpoints that determine how and when the CAST transposase acts.