4F3E: Crystal Structure Of Thermus Thermophilus Hb8 Casa

Prokaryotes make use of small RNAs encoded by CRISPR (clustered regularly interspaced short palindromic repeat) loci to provide immunity against bacteriophage or plasmid invasion. In Escherichia coli, the CRISPR-associated complex for antiviral defense (Cascade) utilizes these RNAs to target foreign DNA for destruction. CasA, the largest subunit of Cascade, is essential for its function. Here we report the crystal structure of Thermus thermophilus CasA. The structure is composed of two domains that are arranged in a chair-like conformation with a novel fold forming the larger N-terminal domain. Docking of the crystal structure into cryo-electron microscopy maps reveals two loops in CasA that likely have important functions in DNA target binding. Finally, DNA binding experiments show that CasA is essential for binding of Cascade to DNA target.
PDB ID: 4F3EDownload
MMDB ID: 99983
PDB Deposition Date: 2012/5/9
Updated in MMDB: 2012/07
Experimental Method:
x-ray diffraction
Resolution: 2.4  Å
Source Organism:
Similar Structures:
Biological Unit for 4F3E: monomeric; determined by author and by software (PISA)
Molecular Components in 4F3E
Label Count Molecule
Protein (1 molecule)
Casa(Gene symbol: TTHB188)
Molecule annotation
* Click molecule labels to explore molecular sequence information.

Citing MMDB