3pkm
From Proteopedia
Crystal structure of Cas6 with its substrate RNA
Structural highlights
Function[CAS6_PYRFU] CRISPR (clustered regularly interspaced short palindromic repeat), is an adaptive immune system that provides protection against mobile genetic elements (viruses, transposable elements and conjugative plasmids). CRISPR clusters contain sequences complementary to antecedent mobile elements and target invading nucleic acids. CRISPR clusters are transcribed and processed into CRISPR RNA (crRNA), also called psiRNA (prokaryotic silencing) in this organism. This protein processes pre-crRNA into individual crRNA units, with an 8-nt 5'-repeat DNA tag that may help other proteins recognize the crRNA. Further processing occurs at their 3' termini in this organism. Generates a 5'-hydroxy and 2',3'-cyclic phosphodiester.[1] [2] Publication Abstract from PubMedThe CRISPRs (Clustered Regularly Interspaced Short Palindromic Repeats) found in prokaryotic genomes confer small RNA-mediated protection against viruses and other invaders. CRISPR loci contain iterations of a short repeat sequence alternating with small segments of varying invader-derived sequences. Distinct families of CRISPR-associated Cas proteins function to cleave within the repeat sequence of CRISPR transcripts and produce the individual invader-targeting crRNAs. Here, we report the crystal structure of Pyrococcus furiosus Cas6 bound with a repeat RNA at 3.2 A resolution. In contrast to other Cas families of endonucleases, Cas6 clasps nucleotides 2-9 of the repeat RNA using its two ferredoxin-like domains, and the enzyme-anchored 5' end tethers the distal cleavage site of the RNA between nucleotides 22 and 23 to the predicted enzyme active site on the opposite side of the ferrodoxin-like domains. Our findings suggest a wrap-around mechanism for CRISPR RNA recognition and cleavage by Cas6 and related processing endonucleases. Interaction of the Cas6 Riboendonuclease with CRISPR RNAs: Recognition and Cleavage.,Wang R, Preamplume G, Terns MP, Terns RM, Li H Structure. 2011 Feb 9;19(2):257-64. PMID:21300293[3] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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