title: Primary processing of CRISPR RNA by the endonuclease Cas6 in Staphylococcus epidermidis.
abstract: In many bacteria and archaea, an adaptive immune system (CRISPR-Cas) provides immunity against foreign genetic elements. This system uses CRISPR RNAs (crRNAs) derived from the CRISPR array, along with CRISPR-associated (Cas) proteins, to target foreign nucleic acids. In most CRISPR systems, endonucleolytic processing of crRNA precursors (pre-crRNAs) is essential for the pathway. Here we study the Cas6 endonuclease responsible for crRNA processing in the Type III-A CRISPR-Cas system from Staphylococcus epidermidis RP62a, a model for Type III-A CRISPR-Cas systems, and define substrate requirements for SeCas6 activity. We find that SeCas6 is necessary and sufficient for full-length crRNA biogenesis in vitro, and that it relies on both sequence and stem-loop structure in the 3' half of the CRISPR repeat for recognition and processing.
authors.affiliation: Department of Molecular Biosciences, Northwestern University, 2205 Tech Drive, Evanston, IL 60208-3500, USA.
authors.forename: Noelle
authors.initials: N
authors.lastname: Wakefield
authors.affiliation: Department of Molecular Biosciences, Northwestern University, 2205 Tech Drive, Evanston, IL 60208-3500, USA.
authors.forename: Rakhi
authors.initials: R
authors.lastname: Rajan
authors.affiliation: Department of Molecular Biosciences, Northwestern University, 2205 Tech Drive, Evanston, IL 60208-3500, USA. Electronic address: erik.sontheimer@umassmed.edu.
authors.forename: Erik J
authors.initials: EJ
authors.lastname: Sontheimer
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism; D001483:Base Sequence; D064113:CRISPR-Cas Systems / Q000235:genetics*; D064112:Clustered Regularly Interspaced Short Palindromic Repeats / Q000235:genetics*; D004591:Electrophoresis, Polyacrylamide Gel; D004720:Endonucleases / Q000235:genetics* / Q000378:metabolism; D008957:Models, Genetic; D009690:Nucleic Acid Conformation; D012313:RNA / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D012322:RNA Precursors / Q000235:genetics / Q000378:metabolism; D013212:Staphylococcus epidermidis / Q000235:genetics* / Q000378:metabolism; D013379:Substrate Specificity
chemical_list: D001426:Bacterial Proteins; D012322:RNA Precursors; D012313:RNA; D004720:Endonucleases
keywords: CRISPR; CRISPR-associated; Cas6; Clustered regularly interspaced short palindromic repeats; RNA processing