title: Crystal Structure of Streptococcus pyogenes Cas1 and Its Interaction with Csn2 in the Type II CRISPR-Cas System.
abstract: CRISPRs and Cas proteins constitute an RNA-guided microbial immune system against invading nucleic acids. Cas1 is a universal Cas protein found in all three types of CRISPR-Cas systems, and its role is implicated in new spacer acquisition during CRISPR-mediated adaptive immunity. Here, we report the crystal structure of Streptococcus pyogenes Cas1 (SpCas1) in a type II CRISPR-Cas system and characterize its interaction with S. pyogenes Csn2 (SpCsn2). The SpCas1 structure reveals a unique conformational state distinct from type I Cas1 structures, resulting in a more extensive dimerization interface, a more globular overall structure, and a disruption of potential metal-binding sites for catalysis. We demonstrate that SpCas1 directly interacts with SpCsn2, and identify the binding interface and key residues for Cas complex formation. These results provide structural information for a type II Cas1 protein, and lay a foundation for studying multiprotein Cas complexes functioning in type II CRISPR-Cas systems.
authors.affiliation: Department of Agricultural Biotechnology, Seoul National University, Seoul 151-921, Korea.
authors.forename: Donghyun
authors.initials: D
authors.lastname: Ka
authors.affiliation: Department of Chemistry, Seoul National University, Seoul 151-747, Korea.
authors.forename: Hasup
authors.initials: H
authors.lastname: Lee
authors.affiliation: Stem Cell Center, Asan Institute for Life Sciences, Asan Medical Center, Seoul 138-736, Korea.
authors.forename: Yi-Deun
authors.initials: YD
authors.lastname: Jung
authors.affiliation: Clinical Proteomics Core Lab, Asan Institute for Life Sciences, Asan Medical Center, Seoul 138-736, Korea; Department of Convergence Medicine, University of Ulsan College of Medicine, Seoul 138-736, Korea.
authors.forename: Kyunggon
authors.initials: K
authors.lastname: Kim
authors.affiliation: Department of Chemistry, Seoul National University, Seoul 151-747, Korea.
authors.forename: Chaok
authors.initials: C
authors.lastname: Seok
authors.affiliation: Stem Cell Center, Asan Institute for Life Sciences, Asan Medical Center, Seoul 138-736, Korea; Department of Convergence Medicine, University of Ulsan College of Medicine, Seoul 138-736, Korea.
authors.forename: Nayoung
authors.initials: N
authors.lastname: Suh
authors.affiliation: Department of Agricultural Biotechnology, Seoul National University, Seoul 151-921, Korea; Center for Food and Bioconvergence, Seoul National University, Seoul 151-921, Korea; Research Institute of Agriculture and Life Sciences, Seoul National University, Seoul 151-921, Korea. Electronic address: bae@snu.ac.kr.
authors.forename: Euiyoung
authors.initials: E
authors.lastname: Bae
mesh_terms: D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000737:chemistry* / Q000378:metabolism; D001665:Binding Sites; D064130:CRISPR-Associated Proteins / Q000737:chemistry* / Q000378:metabolism; D064113:CRISPR-Cas Systems; D018360:Crystallography, X-Ray; D004706:Endodeoxyribonucleases / Q000737:chemistry* / Q000378:metabolism; D008969:Molecular Sequence Data; D011485:Protein Binding; D013297:Streptococcus pyogenes / Q000201:enzymology*
chemical_list: D001426:Bacterial Proteins; D064130:CRISPR-Associated Proteins; D004706:Endodeoxyribonucleases