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PDBsum entry 2wc9
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Viral protein
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PDB id
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2wc9
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References listed in PDB file
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Key reference
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Title
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Structural basis for the nuclease activity of a bacteriophage large terminase.
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Authors
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C.Smits,
M.Chechik,
O.V.Kovalevskiy,
M.B.Shevtsov,
A.W.Foster,
J.C.Alonso,
A.A.Antson.
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Ref.
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Embo Rep, 2009,
10,
592-598.
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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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The DNA-packaging motor in tailed bacteriophages requires nuclease activity to
ensure that the genome is packaged correctly. This nuclease activity is tightly
regulated as the enzyme is inactive for the duration of DNA translocation. Here,
we report the X-ray structure of the large terminase nuclease domain from
bacteriophage SPP1. Similarity with the RNase H family endonucleases allowed
interactions with the DNA to be predicted. A structure-based alignment with the
distantly related T4 gp17 terminase shows the conservation of an extended
beta-sheet and an auxiliary beta-hairpin that are not found in other RNase H
family proteins. The model with DNA suggests that the beta-hairpin partly blocks
the active site, and in vivo activity assays show that the nuclease domain is
not functional in the absence of the ATPase domain. Here, we propose that the
nuclease activity is regulated by movement of the beta-hairpin, altering active
site access and the orientation of catalytically essential residues.
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