Publications
CellMar 2021 |
184
(
9
),
2441-2453.e18
DOI:
10.1016/j.cell.2021.03.006

Dual modes of CRISPR-associated transposon homing

Saito, Makoto; Ladha, Alim; Strecker, Jonathan; Faure, Guilhem; Neumann, Edwin; Altae-Tran, Han; Macrae, Rhiannon K; Zhang, Feng
Product Used
Genes
Abstract
Tn7-like transposons have co-opted CRISPR systems, including class 1 type I-F, I-B, and class 2 type V-K. Intriguingly, although these CRISPR-associated transposases (CASTs) undergo robust CRISPR RNA (crRNA)-guided transposition, they are almost never found in sites targeted by the crRNAs encoded by the cognate CRISPR array. To understand this paradox, we investigated CAST V-K and I-B systems and found two distinct modes of transposition: (1) crRNA-guided transposition and (2) CRISPR array-independent homing. We show distinct CAST systems utilize different molecular mechanisms to target their homing site. Type V-K CAST systems use a short, delocalized crRNA for RNA-guided homing, whereas type I-B CAST systems, which contain two distinct target selector proteins, use TniQ for RNA-guided DNA transposition and TnsD for homing to an attachment site. These observations illuminate a key step in the life cycle of CAST systems and highlight the diversity of molecular mechanisms mediating transposon homing.
Product Used
Genes

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