Abstract
Many bacteria and archaea contain clustered regularly interspaced short palindromic repeats (CRISPRs) that confer resistance to invasive genetic elements. Central to this immune system is the production of CRISPR-derived RNAs (crRNAs) after transcription of the CRISPR locus. Here, we identify the endoribonuclease (Csy4) responsible for CRISPR transcript (pre-crRNA) processing in Pseudomonas aeruginosa. A 1.8 angstrom crystal structure of Csy4 bound to its cognate RNA reveals that Csy4 makes sequence-specific interactions in the major groove of the crRNA repeat stem-loop. Together with electrostatic contacts to the phosphate backbone, these enable Csy4 to bind selectively and cleave pre-crRNAs using phylogenetically conserved serine and histidine residues in the active site. The RNA recognition mechanism identified here explains sequence- and structure-specific processing by a large family of CRISPR-specific endoribonucleases.
Publication types
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Research Support, N.I.H., Extramural
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Research Support, Non-U.S. Gov't
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Research Support, U.S. Gov't, Non-P.H.S.
MeSH terms
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Amino Acid Substitution
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Bacterial Proteins / chemistry*
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Bacterial Proteins / metabolism*
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Base Pairing
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Base Sequence
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CRISPR-Associated Proteins
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Crystallization
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Crystallography, X-Ray
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Endoribonucleases / chemistry*
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Endoribonucleases / metabolism*
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Genes, Bacterial
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Hydrogen Bonding
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Models, Molecular
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Nucleic Acid Conformation
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Protein Conformation
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Protein Structure, Tertiary
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Pseudomonas aeruginosa / enzymology*
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Pseudomonas aeruginosa / genetics*
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RNA Processing, Post-Transcriptional*
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RNA, Bacterial / chemistry
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RNA, Bacterial / genetics
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RNA, Bacterial / metabolism*
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Repetitive Sequences, Nucleic Acid*
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Static Electricity
Substances
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Bacterial Proteins
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CRISPR-Associated Proteins
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RNA, Bacterial
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Csy4 endoribonuclease, Pseudomonas aeruginosa
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Endoribonucleases
Associated data
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PDB/2XLI
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PDB/2XLJ
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PDB/2XLK