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Science. 2016 Feb 26;351(6276):aad4234. doi: 10.1126/science.aad4234.

Direct CRISPR spacer acquisition from RNA by a natural reverse transcriptase-Cas1 fusion protein.

Author information

1
Department of Pathology, Stanford University, Stanford CA 94305, USA.
2
Department of Chemical and Systems Biology, Stanford University, Stanford CA 94305, USA.
3
Institute for Cellular and Molecular Biology, Department of Molecular Biosciences, University of Texas at Austin, Austin TX 78712, USA.
4
Department of Genetics and Microbiology, Universidad de Murcia, Murcia 30100, Spain.
5
Department of Plant Biology, Carnegie Institution for Science, Stanford CA 94305, USA.
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Contributed equally

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.

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PMID:
26917774
PMCID:
PMC4898656
DOI:
10.1126/science.aad4234
[Indexed for MEDLINE]
Free PMC Article
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