5U0A
CRISPR RNA-guided surveillance complex
Summary for 5U0A
| Entry DOI | 10.2210/pdb5u0a/pdb |
| Related | 5U07 |
| EMDB information | 8477 8478 |
| Descriptor | CRISPR-associated protein, Cse3 family, CRISPR-associated protein, Cse1 family, CRISPR-associated protein, Cse4 family, ... (8 entities in total) |
| Functional Keywords | crispr-cas, cascacde, surveillance, immune system |
| Biological source | Thermobifida fusca (strain YX) More |
| Total number of polymer chains | 14 |
| Total formula weight | 464311.24 |
| Authors | |
| Primary citation | Xiao, Y.,Luo, M.,Hayes, R.P.,Kim, J.,Ng, S.,Ding, F.,Liao, M.,Ke, A. Structure Basis for Directional R-loop Formation and Substrate Handover Mechanisms in Type I CRISPR-Cas System. Cell, 170:48-60.e11, 2017 Cited by PubMed Abstract: Type I CRISPR systems feature a sequential dsDNA target searching and degradation process, by crRNA-displaying Cascade and nuclease-helicase fusion enzyme Cas3, respectively. Here we present two cryo-EM snapshots of the Thermobifida fusca type I-E Cascade: (1) unwinding 11 bp of dsDNA at the seed-sequence region to scout for sequence complementarity, and (2) further unwinding of the entire protospacer to form a full R-loop. These structures provide the much-needed temporal and spatial resolution to resolve key mechanistic steps leading to Cas3 recruitment. In the early steps, PAM recognition causes severe DNA bending, leading to spontaneous DNA unwinding to form a seed-bubble. The full R-loop formation triggers conformational changes in Cascade, licensing Cas3 to bind. The same process also generates a bulge in the non-target DNA strand, enabling its handover to Cas3 for cleavage. The combination of both negative and positive checkpoints ensures stringent yet efficient target degradation in type I CRISPR-Cas systems. PubMed: 28666122DOI: 10.1016/j.cell.2017.06.012 PDB entries with the same primary citation |
| Experimental method | ELECTRON MICROSCOPY (3.3 Å) |
Structure validation
Download full validation report
