Abstract
A multi-subunit ribonucleoprotein complex termed the Cmr RNA-silencing complex recognizes and destroys viral RNA in the CRISPR-mediated immune defence mechanism in many prokaryotes using an as yet unclear mechanism. In Archaeoglobus fulgidus, this complex consists of six subunits, Cmr1-Cmr6. Here, the crystal structure of Cmr1 from A. fulgidus is reported, revealing that the protein is composed of two tightly associated ferredoxin-like domains. The domain located at the N-terminus is structurally most similar to the N-terminal ferredoxin-like domain of the CRISPR RNA-processing enzyme Cas6 from Pyrococcus furiosus. An ensuing mutational analysis identified a highly conserved basic surface patch that binds single-stranded nucleic acids specifically, including the mature CRISPR RNA, but in a sequence-independent manner. In addition, this subunit was found to cleave single-stranded RNA. Together, these studies elucidate the structure and the catalytic activity of the Cmr1 subunit.
Keywords:
Archaeoglobus fulgidus; Cmr interference complex; Cmr1 subunit; RNA-binding site.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Amino Acid Sequence
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Archaeal Proteins / chemistry*
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Archaeal Proteins / genetics
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Archaeal Proteins / metabolism
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Archaeoglobus fulgidus / chemistry*
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Archaeoglobus fulgidus / immunology
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Archaeoglobus fulgidus / virology
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Binding Sites
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Clustered Regularly Interspaced Short Palindromic Repeats / genetics*
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Clustered Regularly Interspaced Short Palindromic Repeats / immunology
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Crystallography, X-Ray
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Escherichia coli / genetics
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Escherichia coli / metabolism
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Ferredoxins / chemistry
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Ferredoxins / genetics
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Ferredoxins / metabolism
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Host-Pathogen Interactions
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Models, Molecular
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Molecular Sequence Data
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Protein Structure, Secondary
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Protein Structure, Tertiary
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Protein Subunits / chemistry*
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Protein Subunits / genetics
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Protein Subunits / metabolism
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Pyrococcus furiosus / chemistry
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Pyrococcus furiosus / genetics
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RNA, Viral / chemistry*
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RNA, Viral / metabolism
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Recombinant Proteins / chemistry
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Recombinant Proteins / genetics
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Recombinant Proteins / metabolism
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Sequence Alignment
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Structural Homology, Protein
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Substrate Specificity
Substances
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Archaeal Proteins
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Ferredoxins
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Protein Subunits
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RNA, Viral
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Recombinant Proteins