4AN8
Structure of Thermus thermophilus CasA (Cse1)
Summary for 4AN8
| Entry DOI | 10.2210/pdb4an8/pdb |
| Descriptor | CSE1, ACETATE ION (3 entities in total) |
| Functional Keywords | immune system, crispr, cascade, casa |
| Biological source | THERMUS THERMOPHILUS |
| Total number of polymer chains | 2 |
| Total formula weight | 113267.89 |
| Authors | Sashital, D.G.,Wiedenheft, B.,Doudna, J.A. (deposition date: 2012-03-16, release date: 2012-05-02, Last modification date: 2024-11-20) |
| Primary citation | Sashital, D.G.,Wiedenheft, B.,Doudna, J.A. Mechanism of Foreign DNA Selection in a Bacterial Adaptive Immune System. Mol.Cell, 46:606-, 2012 Cited by PubMed Abstract: In bacterial and archaeal CRISPR immune pathways, DNA sequences from invading bacteriophage or plasmids are integrated into CRISPR loci within the host genome, conferring immunity against subsequent infections. The ribonucleoprotein complex Cascade utilizes RNAs generated from these loci to target complementary "nonself" DNA sequences for destruction, while avoiding binding to "self" sequences within the CRISPR locus. Here we show that CasA, the largest protein subunit of Cascade, is required for nonself target recognition and binding. Combining a 2.3 Å crystal structure of CasA with cryo-EM structures of Cascade, we have identified a loop that is required for viral defense. This loop contacts a conserved three base pair motif that is required for nonself target selection. Our data suggest a model in which the CasA loop scans DNA for this short motif prior to target destabilization and binding, maximizing the efficiency of DNA surveillance by Cascade. PubMed: 22521690DOI: 10.1016/J.MOLCEL.2012.03.020 PDB entries with the same primary citation |
| Experimental method | X-RAY DIFFRACTION (2.3 Å) |
Structure validation
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