8GI1

Homo-octamer of PbuCsx28 protein

Summary for 8GI1

• Entry DOI: 10.2210/pdb8gi1/pdb
• EMDB information: 40059
• Descriptor: Accessory protein Csx28 (1 entity in total)
• Functional Keywords: crispr-associated protein, antiviral protein
• Biological source: Prevotella buccae
• Total number of polymer chains: 8
• Total formula weight: 175281.54

Authors

Park, J.U.,Kellogg, E.H. (deposition date: 2023-03-13, release date: 2023-04-26, Last modification date: 2024-06-19)

Primary citation

VanderWal, A.R.,Park, J.U.,Polevoda, B.,Nicosia, J.K.,Molina Vargas, A.M.,Kellogg, E.H.,O'Connell, M.R.
Csx28 is a membrane pore that enhances CRISPR-Cas13b-dependent antiphage defense.
Science, 380:410-415, 2023

PubMed Abstract: 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.

PubMed: 37104586
DOI: 10.1126/science.abm1184

Experimental method

ELECTRON MICROSCOPY (3.65 Å)