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PDBsum entry 3nkd
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Immune system
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PDB id
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3nkd
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References listed in PDB file
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Key reference
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Title
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A dual function of the crispr-Cas system in bacterial antivirus immunity and DNA repair.
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Authors
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M.Babu,
N.Beloglazova,
R.Flick,
C.Graham,
T.Skarina,
B.Nocek,
A.Gagarinova,
O.Pogoutse,
G.Brown,
A.Binkowski,
S.Phanse,
A.Joachimiak,
E.V.Koonin,
A.Savchenko,
A.Emili,
J.Greenblatt,
A.M.Edwards,
A.F.Yakunin.
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Ref.
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Mol Microbiol, 2011,
79,
484-502.
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PubMed id
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Note: In the PDB file this reference is
annotated as "TO BE PUBLISHED". The citation details given above have
been manually determined.
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Abstract
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Clustered Regularly Interspaced Short Palindromic Repeats (CRISPRs) and the
associated proteins (Cas) comprise a system of adaptive immunity against viruses
and plasmids in prokaryotes. Cas1 is a CRISPR-associated protein that is common
to all CRISPR-containing prokaryotes but its function remains obscure. Here we
show that the purified Cas1 protein of Escherichia coli (YgbT) exhibits nuclease
activity against single-stranded and branched DNAs including Holliday junctions,
replication forks and 5'-flaps. The crystal structure of YgbT and site-directed
mutagenesis have revealed the potential active site. Genome-wide screens show
that YgbT physically and genetically interacts with key components of DNA repair
systems, including recB, recC and ruvB. Consistent with these findings, the ygbT
deletion strain showed increased sensitivity to DNA damage and impaired
chromosomal segregation. Similar phenotypes were observed in strains with
deletion of CRISPR clusters, suggesting that the function of YgbT in repair
involves interaction with the CRISPRs. These results show that YgbT belongs to a
novel, structurally distinct family of nucleases acting on branched DNAs and
suggest that, in addition to antiviral immunity, at least some components of the
CRISPR-Cas system have a function in DNA repair.
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