ジャーナル: Mol Cell / 年: 2020 タイトル: Structures of the Cmr-β Complex Reveal the Regulation of the Immunity Mechanism of Type III-B CRISPR-Cas. 著者: Nicholas Sofos / Mingxia Feng / Stefano Stella / Tillmann Pape / Anders Fuglsang / Jinzhong Lin / Qihong Huang / Yingjun Li / Qunxin She / Guillermo Montoya / 要旨: Cmr-β is a type III-B CRISPR-Cas complex that, upon target RNA recognition, unleashes a multifaceted immune response against invading genetic elements, including single-stranded DNA (ssDNA) ...Cmr-β is a type III-B CRISPR-Cas complex that, upon target RNA recognition, unleashes a multifaceted immune response against invading genetic elements, including single-stranded DNA (ssDNA) cleavage, cyclic oligoadenylate synthesis, and also a unique UA-specific single-stranded RNA (ssRNA) hydrolysis by the Cmr2 subunit. Here, we present the structure-function relationship of Cmr-β, unveiling how binding of the target RNA regulates the Cmr2 activities. Cryoelectron microscopy (cryo-EM) analysis revealed the unique subunit architecture of Cmr-β and captured the complex in different conformational stages of the immune response, including the non-cognate and cognate target-RNA-bound complexes. The binding of the target RNA induces a conformational change of Cmr2, which together with the complementation between the 5' tag in the CRISPR RNAs (crRNA) and the 3' antitag of the target RNA activate different configurations in a unique loop of the Cmr3 subunit, which acts as an allosteric sensor signaling the self- versus non-self-recognition. These findings highlight the diverse defense strategies of type III complexes.
分子 #4: CRISPR-associated RAMP protein, Cmr6 family
分子
名称: CRISPR-associated RAMP protein, Cmr6 family / タイプ: protein_or_peptide / ID: 4 詳細: C-terminal Histidine tag added recombinantly to this protein, in order to co-purify the complex. コピー数: 1 / 光学異性体: LEVO
名称: Cmr1 / タイプ: protein_or_peptide / ID: 5 詳細: The N-terminus has a short additional sequence, "MEELL", compared to the annotated version of this protein コピー数: 1 / 光学異性体: LEVO