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PDBsum entry 4qos
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Transcription
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PDB id
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4qos
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References listed in PDB file
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Key reference
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Title
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Molecular basis of nucleotide-Dependent substrate engagement and remodeling by an aaa+ activator.
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Authors
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V.C.Darbari,
E.Lawton,
D.Lu,
P.C.Burrows,
S.Wiesler,
N.Joly,
N.Zhang,
X.Zhang,
M.Buck.
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Ref.
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Nucleic Acids Res, 2014,
42,
9249-9261.
[DOI no: ]
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PubMed id
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Abstract
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Binding and hydrolysis of ATP is universally required by AAA+ proteins to
underpin their mechano-chemical work. Here we explore the roles of the ATPase
site in an AAA+ transcriptional activator protein, the phage shock protein F
(PspF), by specifically altering the Walker B motif sequence required in
catalyzing ATP hydrolysis. One such mutant, the E108Q variant, is defective in
ATP hydrolysis but fully remodels target transcription complexes, the
RNAP-σ(54) holoenzyme, in an ATP dependent manner. Structural analysis of the
E108Q variant reveals that unlike wild-type protein, which has distinct
conformations for E108 residue in the ATP and ADP bound forms, E108Q adapts the
same conformation irrespective of nucleotide bound. Our data show that the
remodeling activities of E108Q are strongly favored on pre-melted DNA and
engagement with RNAP-σ(54) using ATP binding can be sufficient to convert the
inactive holoenzyme to an active form, while hydrolysis per se is required for
nucleic acid remodeling that leads to transcription bubble formation.
Furthermore, using linked dimer constructs, we show that RNAP-σ(54) engagement
by adjacent subunits within a hexamer are required for this protein remodeling
activity while DNA remodeling activity can tolerate defective ATP hydrolysis of
alternating subunits.
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