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PDBsum entry 3llm
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References listed in PDB file
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Key reference
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Title
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Crystal structure of human RNA helicase a (dhx9): structural basis for unselective nucleotide base binding in a dead-Box variant protein.
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Authors
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P.Schütz,
E.Wahlberg,
T.Karlberg,
M.Hammarström,
R.Collins,
A.Flores,
H.Schüler.
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Ref.
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J Mol Biol, 2010,
400,
768-782.
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PubMed id
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Abstract
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RNA helicases of the DExD/H-box superfamily are critically involved in all RNA
related processes. Previously, no crystal structures of human DExH-box domains
had been determined, and their structures were difficult to predict owing to the
low homology among DExH-motif containing proteins from diverse species. Here we
present crystal structures of the conserved domains-1 of the DEIH-motif
containing helicase DHX9 and of the DEAD-box helicase DDX20. Both contain a
RecA-like core, but DHX9 differs from DEAD-box proteins in the arrangement of
secondary structural elements, and is more similar to viral helicases such as
NS3. The N-terminus of the DHX9 core contains two long alpha-helices that reside
on the surface of the core without contributing to nucleotide binding. The RNA
polymerase-II interacting MTAD sequence forms an extended loop structure that
resides in a hydrophobic groove on the surface of the DEIH domain. DHX9 lacks
base-selective contacts and forms an unspecific but important stacking
interaction with the base of the bound nucleotide, and our biochemical analysis
confirms that the protein can hydrolyze ATP, GTP, CTP, and UTP. Together, these
findings allow localization of functional motifs within the three-dimensional
structure of a human DEIH helicase, and show how these enzymes can bind
nucleotide with high affinity in the absence of a Q-motif.
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