title: Recognition and cleavage of a nonstructured CRISPR RNA by its processing endoribonuclease Cas6.
abstract: Clustered regularly interspaced short palindromic repeats (CRISPRs) confer adaptive immunity to prokaryotes through a small RNA-mediated mechanism. Specific endoribonucleases are required by all CRISPR-bearing organisms to process CRISPR RNAs into small RNA that serve as guides for defensive effector complexes. The molecular mechanism of how the endoribonucleases process the class of CRISPR RNA containing no predicted secondary structural features remains largely elusive. Here, we report cocrystal structures of a processing endoribonuclease bound with a noncleavable RNA substrate and its product-like fragment derived from a nonpalindramic repeat. The enzyme stabilizes a short RNA stem-loop structure near the cleavage site and cleaves the phosphodiester bond using an active site comprised of arginine and lysine residues. The distinct RNA binding and cleavage mechanisms underline the diversity in CRISPR RNA processing.
authors: Institute of Molecular Biophysics, Department of Chemistry and Biochemistry, Florida State University, Tallahassee, FL 32306, USA
authors: Yaming
authors: Y
authors: Shao
authors: Hong
authors: H
authors: Li
mesh_terms: D019843:Archaeal Proteins / Q000737:chemistry* / Q000235:genetics; D001483:Base Sequence; D001665:Binding Sites; D018360:Crystallography, X-Ray; D004722:Endoribonucleases / Q000737:chemistry* / Q000235:genetics; D004926:Escherichia coli / Q000737:chemistry / Q000235:genetics; D056004:Molecular Dynamics Simulation; D008969:Molecular Sequence Data; D009154:Mutation; D009690:Nucleic Acid Conformation; D011485:Protein Binding; D054730:Protein Interaction Domains and Motifs; D017433:Protein Structure, Secondary; D021122:Protein Subunits / Q000737:chemistry* / Q000235:genetics; D059367:RNA Cleavage; D020871:RNA Stability; D019642:RNA, Archaeal / Q000737:chemistry* / Q000235:genetics; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics; D048229:Sulfolobus solfataricus / Q000737:chemistry* / Q000235:genetics / Q000276:immunology
chemical_list: D019843:Archaeal Proteins; D021122:Protein Subunits; D019642:RNA, Archaeal; D011994:Recombinant Proteins; D004722:Endoribonucleases