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 [[cite:PUB00085375]]. Four Cas proteins (Cas5, Cas6b, Cas7 and Cas8b) are proposed to form a Type I-B Cascade complex that mediates the antiviral defense [[cite:PUB00085160]]. 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 [[cite:PUB00085376]].
","llm":false,"checked":false,"updated":false}],"wikipedia":[{"title":"CRISPR","extract":"CRISPR is a family of DNA sequences found in the genomes of prokaryotic organisms such as bacteria and archaea. Each sequence within an individual prokaryotic CRISPR is derived from a DNA fragment of a bacteriophage that had previously infected the prokaryote or one of its ancestors. These sequences are used to detect and destroy DNA from similar bacteriophages during subsequent infections. Hence these sequences play a key role in the antiviral defense system of prokaryotes and provide a form of heritable, acquired immunity. CRISPR is found in approximately 50% of sequenced bacterial genomes and nearly 90% of sequenced archaea.
","thumbnail":null}],"literature":{"PUB00085375":{"PMID":25451598,"ISBN":null,"volume":"427","issue":"2","year":2015,"title":"Crystal structure of the Csm3-Csm4 subcomplex in the type III-A CRISPR-Cas interference complex.","URL":null,"raw_pages":"259-73","medline_journal":"J Mol Biol","ISO_journal":"J. Mol. Biol.","authors":["Numata T","Inanaga H","Sato C","Osawa T."],"DOI_URL":"https://doi.org/10.1016/j.jmb.2014.09.029"},"PUB00085376":{"PMID":26996962,"ISBN":null,"volume":"24","issue":"4","year":2016,"title":"A Non-Stem-Loop CRISPR RNA Is Processed by Dual Binding Cas6.","URL":null,"raw_pages":"547-54","medline_journal":"Structure","ISO_journal":"Structure","authors":["Shao Y","Richter H","Sun S","Sharma K","Urlaub H","Randau L","Li H."],"DOI_URL":"https://doi.org/10.1016/j.str.2016.02.009"},"PUB00085160":{"PMID":28238733,"ISBN":null,"volume":null,"issue":null,"year":2017,"title":"Fragmentation of the CRISPR-Cas Type I-B signature protein Cas8b.","URL":null,"raw_pages":null,"medline_journal":"Biochim Biophys Acta","ISO_journal":"Biochim. Biophys. Acta","authors":["Richter H","Rompf J","Wiegel J","Rau K","Randau L."],"DOI_URL":"https://doi.org/10.1016/j.bbagen.2017.02.026"}},"set_info":{"accession":"CL0362","name":"RAMPS-Cas5-like"},"overlaps_with":null,"counters":{"subfamilies":0,"domain_architectures":2,"interactions":0,"matches":251,"pathways":0,"proteins":251,"proteomes":213,"sets":1,"structural_models":{"alphafold":202},"structures":2,"taxa":538},"entry_annotations":{"hmm":0,"logo":0,"alignment:seed":29,"alignment:full":133},"cross_references":{},"is_llm":false,"is_reviewed_llm":false,"is_updated_llm":false,"representative_structure":null}}