4F3E

Crystal Structure of Thermus thermophilus HB8 CasA

Summary for 4F3E

• Entry DOI: 10.2210/pdb4f3e/pdb
• Descriptor: CasA (2 entities in total)
• Functional Keywords: four helix bundle, cascade complex, immune system
• Biological source: Thermus thermophilus
• Total number of polymer chains: 2
• Total formula weight: 112546.25

Authors

Bailey, S.,Mulepati, S. (deposition date: 2012-05-09, release date: 2012-05-23, Last modification date: 2024-10-30)

Primary citation

Mulepati, S.,Orr, A.,Bailey, S.
Crystal Structure of the Largest Subunit of a Bacterial RNA-guided Immune Complex and Its Role in DNA Target Binding.
J.Biol.Chem., 287:22445-22449, 2012

PubMed Abstract: 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.

PubMed: 22621933
DOI: 10.1074/jbc.C112.379503

Experimental method

X-RAY DIFFRACTION (2.4 Å)