3S5U
Crystal structure of CRISPR associated protein
Summary for 3S5U
| Entry DOI | 10.2210/pdb3s5u/pdb |
| Descriptor | Putative uncharacterized protein, CALCIUM ION (3 entities in total) |
| Functional Keywords | crispr, crispr adaptation mechanism, new spacer aquisition, dsdna binding, dna binding protein |
| Biological source | Enterococcus faecalis |
| Total number of polymer chains | 8 |
| Total formula weight | 204786.84 |
| Authors | |
| Primary citation | Nam, K.H.,Kurinov, I.,Ke, A. Crystal structure of clustered regularly interspaced short palindromic repeats (CRISPR)-associated Csn2 protein revealed Ca2+-dependent double-stranded DNA binding activity. J. Biol. Chem., 286:30759-30768, 2011 Cited by PubMed Abstract: Clustered regularly interspaced short palindromic repeats (CRISPR) and their associated protein genes (cas genes) are widespread in bacteria and archaea. They form a line of RNA-based immunity to eradicate invading bacteriophages and malicious plasmids. A key molecular event during this process is the acquisition of new spacers into the CRISPR loci to guide the selective degradation of the matching foreign genetic elements. Csn2 is a Nmeni subtype-specific cas gene required for new spacer acquisition. Here we characterize the Enterococcus faecalis Csn2 protein as a double-stranded (ds-) DNA-binding protein and report its 2.7 Å tetrameric ring structure. The inner circle of the Csn2 tetrameric ring is ∼26 Å wide and populated with conserved lysine residues poised for nonspecific interactions with ds-DNA. Each Csn2 protomer contains an α/β domain and an α-helical domain; significant hinge motion was observed between these two domains. Ca(2+) was located at strategic positions in the oligomerization interface. We further showed that removal of Ca(2+) ions altered the oligomerization state of Csn2, which in turn severely decreased its affinity for ds-DNA. In summary, our results provided the first insight into the function of the Csn2 protein in CRISPR adaptation by revealing that it is a ds-DNA-binding protein functioning at the quaternary structure level and regulated by Ca(2+) ions. PubMed: 21697083DOI: 10.1074/jbc.M111.256263 PDB entries with the same primary citation |
| Experimental method | X-RAY DIFFRACTION (2.7 Å) |
Structure validation
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