TY - JOUR TI - Disintegration promotes protospacer integration by the Cas1-Cas2 complex AU - Ma, Chien-Hui AU - Javanmardi, Kamyab AU - Finkelstein, Ilya J AU - Jayaram, Makkuni A2 - Berger, James M A2 - Storz, Gisela VL - 10 PY - 2021 DA - 2021/08/26 SP - e65763 C1 - eLife 2021;10:e65763 DO - 10.7554/eLife.65763 UR - https://doi.org/10.7554/eLife.65763 AB - ‘Disintegration’—the reversal of transposon DNA integration at a target site—is regarded as an abortive off-pathway reaction. Here, we challenge this view with a biochemical investigation of the mechanism of protospacer insertion, which is mechanistically analogous to DNA transposition, by the Streptococcus pyogenes Cas1-Cas2 complex. In supercoiled target sites, the predominant outcome is the disintegration of one-ended insertions that fail to complete the second integration event. In linear target sites, one-ended insertions far outnumber complete protospacer insertions. The second insertion event is most often accompanied by the disintegration of the first, mediated either by the 3′-hydroxyl exposed during integration or by water. One-ended integration intermediates may mature into complete spacer insertions via DNA repair pathways that are also involved in transposon mobility. We propose that disintegration-promoted integration is functionally important in the adaptive phase of CRISPR-mediated bacterial immunity, and perhaps in other analogous transposition reactions. KW - CRISPR KW - adaptation KW - transposition JF - eLife SN - 2050-084X PB - eLife Sciences Publications, Ltd ER -