An archaeal virus-encoded anti-CRISPR protein inhibits type III-B immunity by inhibiting Cas RNP complex turnover.

ABSTRACT: CRISPR-Cas systems are widespread in prokaryotes and provide adaptive immune against viral infection. Viruses encode a type of proteins called anti-CRISPR to evade the immunity. Here, we identify an archaeal virus-encoded anti-CRISPR protein, AcrIIIB2, that inhibits Type III-B immunity. We find that AcrIIIB2 inhibits Type III-B CRISPR-Cas immunity in vivo regardless of viral early or middle-/late-expressed genes to be targeted. We also demonstrate that AcrIIIB2 interacts with Cmr4α subunit, forming a complex with target RNA and Cmr-α ribonucleoprotein complex (RNP). Furtherly, we discover that AcrIIIB2 inhibits the RNase activity, ssDNase activity and cOA synthesis activity of Cmr-α RNP in vitro under a higher target RNA-to-Cmr-α RNP ratio and has no effect on Cmr-α activities at the targe

SUBMITTER: Liu J 

PROVIDER: S-EPMC10681719 | biostudies-literature | 2023 Nov

REPOSITORIES: biostudies-literature