Login / Signup

Csx28 is a membrane pore that enhances CRISPR-Cas13b-dependent antiphage defense.

Arica R VanderWalJung-Un ParkBogdan V PolevodaJulia K NicosiaAdrian M Molina VargasElizabeth H KelloggMitchell R O'Connell
Published in: Science (New York, N.Y.) (2023)
Type VI CRISPR-Cas systems use RNA-guided ribonuclease (RNase) Cas13 to defend bacteria against viruses, and some of these systems encode putative membrane proteins that have unclear roles in Cas13-mediated defense. We show that Csx28, of type VI-B2 systems, is a transmembrane protein that assists to slow cellular metabolism upon viral infection, increasing antiviral defense. High-resolution cryo-electron microscopy reveals that Csx28 forms an octameric pore-like structure. These Csx28 pores localize to the inner membrane in vivo. Csx28's antiviral activity in vivo requires sequence-specific cleavage of viral messenger RNAs by Cas13b, which subsequently results in membrane depolarization, slowed metabolism, and inhibition of sustained viral infection. Our work suggests a mechanism by which Csx28 acts as a downstream, Cas13b-dependent effector protein that uses membrane perturbation as an antiviral defense strategy.
Keyphrases
  • crispr cas
  • genome editing
  • high resolution
  • electron microscopy
  • immune response
  • mass spectrometry
  • protein protein
  • amino acid
  • regulatory t cells