General Information/The casposases
More recently, TE related to CRISPRs, Casposons have been identified and a reassement of their ends has led to the identification of an 14-15 bp target duplication . Moreover, the purified Cas1 enzyme encoded by these ancestral transposons has been demonstrated to catalyse strand transfer of a pre-cleaved transposon in vitro but does not appear to promote transposon strand cleavage in this assay. Cas1 "casposases" use similar chemistry to that used by the CRISPR Cas1-Cas2 complex but with opposite substrate specificities since CRISPR Cas1-Cas2 integrates "random" sequences into a specific site in the CRISPR locus whereas casposases integrate a specific site (the casposon ends) into random target sequences (Fig.24.1).
- Krupovic M, Makarova KS, Forterre P, Prangishvili D, Koonin EV . Casposons: a new superfamily of self-synthesizing DNA transposons at the origin of prokaryotic CRISPR-Cas immunity. - BMC Biol: 2014 May 19, 12;36 [PubMed:24884953] [DOI]
- Hickman AB, Dyda F . CRISPR-Cas immunity and mobile DNA: a new superfamily of DNA transposons encoding a Cas1 endonuclease. - Mob DNA: 2014, 5;23 [PubMed:25180049] [DOI]
- Hickman AB, Dyda F . The casposon-encoded Cas1 protein from Aciduliprofundum boonei is a DNA integrase that generates target site duplications. - Nucleic Acids Res: 2015 Dec 15, 43(22);10576-87 [PubMed:26573596] [DOI]