title: Direct CRISPR spacer acquisition from RNA by a natural reverse transcriptase-Cas1 fusion protein.
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.
authors.affiliation: Department of Pathology, Stanford University, Stanford CA 94305, USA.|Department of Chemical and Systems Biology, Stanford University, Stanford CA 94305, USA.
authors.forename: Sukrit
authors.initials: S
authors.lastname: Silas
authors.affiliation: Institute for Cellular and Molecular Biology, Department of Molecular Biosciences, University of Texas at Austin, Austin TX 78712, USA.
authors.forename: Georg
authors.initials: G
authors.lastname: Mohr
authors.affiliation: Institute for Cellular and Molecular Biology, Department of Molecular Biosciences, University of Texas at Austin, Austin TX 78712, USA.
authors.forename: David J
authors.initials: DJ
authors.lastname: Sidote
authors.affiliation: Institute for Cellular and Molecular Biology, Department of Molecular Biosciences, University of Texas at Austin, Austin TX 78712, USA.
authors.forename: Laura M
authors.initials: LM
authors.lastname: Markham
authors.affiliation: Department of Genetics and Microbiology, Universidad de Murcia, Murcia 30100, Spain.
authors.forename: Antonio
authors.initials: A
authors.lastname: Sanchez-Amat
authors.affiliation: Department of Plant Biology, Carnegie Institution for Science, Stanford CA 94305, USA.
authors.forename: Devaki
authors.initials: D
authors.lastname: Bhaya
authors.affiliation: Institute for Cellular and Molecular Biology, Department of Molecular Biosciences, University of Texas at Austin, Austin TX 78712, USA.
authors.forename: Alan M
authors.initials: AM
authors.lastname: Lambowitz
authors.affiliation: Department of Pathology, Stanford University, Stanford CA 94305, USA.
authors.forename: Andrew Z
authors.initials: AZ
authors.lastname: Fire
mesh_terms: D001426:Bacterial Proteins / Q000145:classification / Q000235:genetics / Q000378:metabolism*; D001483:Base Sequence; D064130:CRISPR-Associated Proteins / Q000145:classification / Q000235:genetics / Q000378:metabolism*; D064113:CRISPR-Cas Systems; D064112:Clustered Regularly Interspaced Short Palindromic Repeats; D004247:DNA / Q000235:genetics; D007438:Introns / Q000235:genetics; D053544:Marinomonas / Q000201:enzymology* / Q000235:genetics; D008969:Molecular Sequence Data; D050506:Mutant Chimeric Proteins / Q000145:classification / Q000235:genetics / Q000378:metabolism*; D010802:Phylogeny; D017434:Protein Structure, Tertiary; D012313:RNA / Q000235:genetics / Q000378:metabolism*; D012326:RNA Splicing; D012194:RNA-Directed DNA Polymerase / Q000145:classification / Q000235:genetics / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; D064130:CRISPR-Associated Proteins; D050506:Mutant Chimeric Proteins; D012313:RNA; D004247:DNA; D012194:RNA-Directed DNA Polymerase