| Structural highlights
Function
CSE1_ECOLI CRISPR (clustered regularly interspaced short palindromic repeat), is an adaptive immune system that provides protection against mobile genetic elements (viruses, transposable elements and conjugative plasmids). CRISPR clusters contain sequences complementary to antecedent mobile elements and target invading nucleic acids. CRISPR clusters are transcribed and processed into CRISPR RNA (crRNA).[1] [2] [3] [4] A component of Cascade, which participates in CRISPR interference, the third stage of CRISPR immunity. Cascade binds both crRNA and in a sequence-specific manner negatively supercoiled dsDNA target. This leads to the formation of an R-loop in which the crRNA binds the target DNA, displacing the noncomplementary strand. Cas3 is recruited to Cascade, probably via interactions with CasA, nicks target DNA and then unwinds and cleaves the target, leading to DNA degradation and invader neutralization. CasA is not required for formation of Cascade, but probably enhances binding to and subsequent recognition of both target dsDNA and ssDNA.[5] [6] [7] [8]
Publication Abstract from PubMed
In prokaryotes, RNA derived from type I and type III CRISPR loci direct large ribonucleoprotein complexes to destroy invading bacteriophage and plasmids. In Escherichia coli, this 405-kDa complex is called Cascade. Here, we report the 3.03A crystal structure of Cascade bound to a single-stranded DNA target. The structure reveals that the CRISPR RNA and target strands do not form a double helix but instead adopt an underwound ribbon-like structure. This non-canonical structure is facilitated by rotation of every sixth nucleotide out of the RNA-DNA hybrid and is stabilized by the highly interlocked organization of protein subunits. These studies provide insight into both the assembly and the activity of this complex and suggest a mechanism to enforce fidelity of target binding.
Crystal structure of a CRISPR RNA-guided surveillance complex bound to a ssDNA target.,Mulepati S, Heroux A, Bailey S Science. 2014 Aug 14. pii: 1256996. PMID:25123481[9]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
See Also
References
- ↑ Perez-Rodriguez R, Haitjema C, Huang Q, Nam KH, Bernardis S, Ke A, DeLisa MP. Envelope stress is a trigger of CRISPR RNA-mediated DNA silencing in Escherichia coli. Mol Microbiol. 2011 Feb;79(3):584-99. doi: 10.1111/j.1365-2958.2010.07482.x. Epub, 2010 Dec 13. PMID:21255106 doi:10.1111/j.1365-2958.2010.07482.x
- ↑ Jore MM, Lundgren M, van Duijn E, Bultema JB, Westra ER, Waghmare SP, Wiedenheft B, Pul U, Wurm R, Wagner R, Beijer MR, Barendregt A, Zhou K, Snijders AP, Dickman MJ, Doudna JA, Boekema EJ, Heck AJ, van der Oost J, Brouns SJ. Structural basis for CRISPR RNA-guided DNA recognition by Cascade. Nat Struct Mol Biol. 2011 May;18(5):529-36. doi: 10.1038/nsmb.2019. Epub 2011 Apr, 3. PMID:21460843 doi:http://dx.doi.org/10.1038/nsmb.2019
- ↑ 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
- ↑ Sashital DG, Wiedenheft B, Doudna JA. Mechanism of Foreign DNA Selection in a Bacterial Adaptive Immune System. Mol Cell. 2012 Apr 17. PMID:22521690 doi:10.1016/j.molcel.2012.03.020
- ↑ Perez-Rodriguez R, Haitjema C, Huang Q, Nam KH, Bernardis S, Ke A, DeLisa MP. Envelope stress is a trigger of CRISPR RNA-mediated DNA silencing in Escherichia coli. Mol Microbiol. 2011 Feb;79(3):584-99. doi: 10.1111/j.1365-2958.2010.07482.x. Epub, 2010 Dec 13. PMID:21255106 doi:10.1111/j.1365-2958.2010.07482.x
- ↑ Jore MM, Lundgren M, van Duijn E, Bultema JB, Westra ER, Waghmare SP, Wiedenheft B, Pul U, Wurm R, Wagner R, Beijer MR, Barendregt A, Zhou K, Snijders AP, Dickman MJ, Doudna JA, Boekema EJ, Heck AJ, van der Oost J, Brouns SJ. Structural basis for CRISPR RNA-guided DNA recognition by Cascade. Nat Struct Mol Biol. 2011 May;18(5):529-36. doi: 10.1038/nsmb.2019. Epub 2011 Apr, 3. PMID:21460843 doi:http://dx.doi.org/10.1038/nsmb.2019
- ↑ 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
- ↑ Sashital DG, Wiedenheft B, Doudna JA. Mechanism of Foreign DNA Selection in a Bacterial Adaptive Immune System. Mol Cell. 2012 Apr 17. PMID:22521690 doi:10.1016/j.molcel.2012.03.020
- ↑ Mulepati S, Heroux A, Bailey S. Crystal structure of a CRISPR RNA-guided surveillance complex bound to a ssDNA target. Science. 2014 Aug 14. pii: 1256996. PMID:25123481 doi:http://dx.doi.org/10.1126/science.1256996
|
