4f3e is a 2 chain structure with sequence from Thermus thermophilus. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance.
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 likely have important functions in DNA target binding. Finally, DNA binding experiments show CasA is essential for binding of Cascade to DNA target.
Crystal structure of the largest subunit of a bacterial RNA-guided immune complex and its role in DNA target binding.,Mulepati S, Orr A, Bailey S J Biol Chem. 2012 May 23. PMID:22621933[1]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
References
↑ 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. 2012 May 23. PMID:22621933 doi:10.1074/jbc.C112.379503
