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PDBsum entry 6b47
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Immune system / RNA
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PDB id
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6b47
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Contents |
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424 a.a.
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305 a.a.
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293 a.a.
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333 a.a.
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87 a.a.
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189 a.a.
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References listed in PDB file
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Key reference
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Title
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Cryo-Em structures reveal mechanism and inhibition of DNA targeting by a crispr-Cas surveillance complex.
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Authors
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T.W.Guo,
A.Bartesaghi,
H.Yang,
V.Falconieri,
P.Rao,
A.Merk,
E.T.Eng,
A.M.Raczkowski,
T.Fox,
L.A.Earl,
D.J.Patel,
S.Subramaniam.
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Ref.
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Cell, 2017,
171,
414.
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PubMed id
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Abstract
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Prokaryotic cells possess CRISPR-mediated adaptive immune systems that protect
them from foreign genetic elements, such as invading viruses. A central element
of this immune system is an RNA-guided surveillance complex capable of targeting
non-self DNA or RNA for degradation in a sequence- and site-specific manner
analogous to RNA interference. Although the complexes display considerable
diversity in their composition and architecture, many basic mechanisms
underlying target recognition and cleavage are highly conserved. Using
cryoelectron microscopy (cryo-EM), we show that the binding of target
double-stranded DNA (dsDNA) to a type I-F CRISPR system yersinia (Csy)
surveillance complex leads to large quaternary and tertiary structural changes
in the complex that are likely necessary in the pathway leading to target dsDNA
degradation by a trans-acting helicase-nuclease. Comparison of the structure of
the surveillance complex before and after dsDNA binding, or in complex with
three virally encoded anti-CRISPR suppressors that inhibit dsDNA binding,
reveals mechanistic details underlying target recognition and inhibition.
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