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PDBsum entry 6c6t
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Transcription/DNA/RNA
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PDB id
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6c6t
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Contents |
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221 a.a.
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1319 a.a.
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1335 a.a.
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83 a.a.
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85 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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Structural basis for transcript elongation control by nusg family universal regulators.
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Authors
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J.Y.Kang,
R.A.Mooney,
Y.Nedialkov,
J.Saba,
T.V.Mishanina,
I.Artsimovitch,
R.Landick,
S.A.Darst.
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Ref.
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Cell, 2018,
173,
1650.
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PubMed id
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Abstract
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NusG/RfaH/Spt5 transcription elongation factors are the only transcription
regulators conserved across all life. Bacterial NusG regulates RNA polymerase
(RNAP) elongation complexes (ECs) across most genes, enhancing elongation by
suppressing RNAP backtracking and coordinating ρ-dependent termination and
translation. The NusG paralog RfaH engages the EC only at operon polarity
suppressor (ops) sites and suppresses both backtrack and hairpin-stabilized
pausing. We used single-particle cryoelectron microscopy (cryo-EM) to determine
structures of ECs at ops with NusG or RfaH. Both factors chaperone base-pairing
of the upstream duplex DNA to suppress backtracking, explaining stimulation of
elongation genome-wide. The RfaH-opsEC structure reveals how RfaH confers operon
specificity through specific recognition of an ops hairpin in the
single-stranded nontemplate DNA and tighter binding to the EC to exclude NusG.
Tight EC binding by RfaH sterically blocks the swiveled RNAP conformation
necessary for hairpin-stabilized pausing. The universal conservation of
NusG/RfaH/Spt5 suggests that the molecular mechanisms uncovered here are
widespread.
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