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Cas6b C-terminal domain Clustered, regularly interspaced, short palindromic repeat (CRISPR) loci play a pivotal role in the prokaryotic host defense system against invading genetic materials. The CRISPR loci are transcribed to produce CRISPR RNAs (crRNAs), which form interference complexes with CRISPR-associated (Cas) proteins to target the invading nucleic acid for degradation. Four Cas proteins (Cas5, Cas6b, Cas7 and Cas8b) are proposed to form a Type I-B Cascade complex that mediates the antiviral defense. This is the C-terminal domain found in Cas6b proteins. Cas6b is a member of Cas6 RNA processing endoribonucleases found in bacteria and archaea whose RNA substrates have a wide range of structural features. Cocrystal structures of Cas6 from Methanococcus maripaludis (MmCas6b) bound with its repeat RNA revealed a dual-site binding structure and a cleavage site conformation poised for phosphodiester bond breakage. |
Jiyao W et al.(2023). "The conserved domain database in 2023.",