CRISPR-associated transposons or CASTs are mobile genetic elements (MGEs) that have evolved to make use of minimal CRISPR systems for RNA-guided transposition of their DNA.
[1] Structural analysis has shown binding of the TnsB protein and sequence specific motifs on the ends of the transposon which allows for excision and mobility.
[13] A Type V-K system was originally characterized from a cyanobacteria, Scytonema hofmanni, and contains a single Cas effector, Cas12k, that functions with a tracrRNA.
[10] The Cas12k and tracrRNA complex bind to the target site and TnsC is polymerized directly adjacent prior to TniQ attachment and TnsB recognition and integration.
[15] Type V-K spacers preferentially target locations near tRNA genes, but other sites have been observed in these short crRNA guides which have been acquired by non-traditional means.
[16] This has also been shown in a community context with conjugative delivery of suicide vectors to provide antibiotic resistance or enhanced metabolic function to only a single microbe.