国内外学术动态
Dual modes of CRISPR-associated transposon homing
文章来源:临床药理研究所    发布时间:2021-03-29    浏览次数:406

Highlights

  • ?

    CRISPR-associated transposases (CASTs) use two mechanisms to home to specific locations within the host genome

     


  • ?

    Type V-K CAST systems utilize delocalized short crRNA for homing

     


  • ?

    Type I-B CAST systems are RNA-guided

     


  • ?

    Type I-B CAST systems harbor dedicated attachment site target proteins for homing

     


Summary

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.
Cell,Published:March 25, 2021DOI:https://doi.org/10.1016/j.cell.2021.03.006