title: Structure of the Cmr2-Cmr3 subcomplex of the Cmr RNA silencing complex.
abstract: The Cmr complex is an RNA-guided effector complex that cleaves invader RNA in the prokaryotic immune response mediated by the CRISPR (Clustered Regularly Interspaced Short Palindromic Repeat)-Cas system. Here, we report the crystal structure of a Cmr subcomplex containing Cmr2 (Cas10) and Cmr3 subunits at 2.8 Å resolution. The structure revealed a dual ferredoxin fold and glycine-rich loops characteristic of previously known repeat-associated mysterious proteins and two unique insertion elements in Cmr3 that mediate its interaction with Cmr2. Surprisingly, while mutation of both insertion elements significantly weakened Cmr3-Cmr2 interaction, they exhibit differential effects on Cmr-mediated RNA cleavage by the Cmr complex, suggesting stabilization of Cmr2-Cmr3 interactions by other subunits. Further mutational analysis of the two conserved (but non-Cmr2-binding) glycine-rich loops of Cmr3 identified a region that is likely involved in assembly or the RNA cleavage function of the Cmr complex.
authors: Institute of Molecular Biophysics, Florida State University, Tallahassee, FL 32306, USA.
authors: Yaming
authors: Y
authors: Shao
authors: Alexis I
authors: AI
authors: Cocozaki
authors: Nancy F
authors: NF
authors: Ramia
authors: Rebecca M
authors: RM
authors: Terns
authors: Michael P
authors: MP
authors: Terns
authors: Hong
authors: H
authors: Li
mesh_terms: D019843:Archaeal Proteins / Q000737:chemistry* / Q000235:genetics; D001665:Binding Sites; D018360:Crystallography, X-Ray; D004926:Escherichia coli / Q000737:chemistry* / Q000235:genetics; D056004:Molecular Dynamics Simulation; D009154:Mutation; D011485:Protein Binding; D054730:Protein Interaction Domains and Motifs; D055550:Protein Stability; D017433:Protein Structure, Secondary; D021122:Protein Subunits / Q000737:chemistry* / Q000235:genetics; D020027:Pyrococcus furiosus / Q000737:chemistry* / Q000235:genetics / Q000276:immunology; D059367:RNA Cleavage; D034622:RNA Interference; D019642:RNA, Archaeal / Q000737:chemistry* / Q000235:genetics; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics
chemical_list: D019843:Archaeal Proteins; D021122:Protein Subunits; D019642:RNA, Archaeal; D011994:Recombinant Proteins
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