Abstract
CRISPR systems mediate adaptive immunity in diverse prokaryotes. CRISPR-associated Cas1 and Cas2 proteins have been shown to enable adaptation to new threats in type I and II CRISPR systems by the acquisition of short segments of DNA (spacers) from invasive elements. In several type III CRISPR systems, Cas1 is naturally fused to a reverse transcriptase (RT). In the marine bacterium Marinomonas mediterranea (MMB-1), we showed that a RT-Cas1 fusion protein enables the acquisition of RNA spacers in vivo in a RT-dependent manner. In vitro, the MMB-1 RT-Cas1 and Cas2 proteins catalyze the ligation of RNA segments into the CRISPR array, which is followed by reverse transcription. These observations outline a host-mediated mechanism for reverse information flow from RNA to DNA.
Copyright © 2016, American Association for the Advancement of Science.
Publication types
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Research Support, N.I.H., Extramural
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Research Support, Non-U.S. Gov't
MeSH terms
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Bacterial Proteins / classification
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Bacterial Proteins / genetics
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Bacterial Proteins / metabolism*
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Base Sequence
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CRISPR-Associated Proteins / classification
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CRISPR-Associated Proteins / genetics
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CRISPR-Associated Proteins / metabolism*
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CRISPR-Cas Systems*
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Clustered Regularly Interspaced Short Palindromic Repeats*
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DNA / genetics
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Introns / genetics
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Marinomonas / enzymology*
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Marinomonas / genetics
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Molecular Sequence Data
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Mutant Chimeric Proteins / classification
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Mutant Chimeric Proteins / genetics
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Mutant Chimeric Proteins / metabolism*
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Phylogeny
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Protein Structure, Tertiary
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RNA / genetics
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RNA / metabolism*
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RNA Splicing
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RNA-Directed DNA Polymerase / classification
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RNA-Directed DNA Polymerase / genetics
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RNA-Directed DNA Polymerase / metabolism*
Substances
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Bacterial Proteins
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CRISPR-Associated Proteins
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Mutant Chimeric Proteins
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RNA
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DNA
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RNA-Directed DNA Polymerase