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PDBsum entry 1twc
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Transcription
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PDB id
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1twc
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Contents |
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1351 a.a.
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1091 a.a.
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266 a.a.
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215 a.a.
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83 a.a.
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133 a.a.
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121 a.a.
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64 a.a.
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114 a.a.
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46 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 of transcription: nucleotide selection by rotation in the RNA polymerase ii active center.
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Authors
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K.D.Westover,
D.A.Bushnell,
R.D.Kornberg.
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Ref.
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Cell, 2004,
119,
481-489.
[DOI no: ]
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PubMed id
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Abstract
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Binding of a ribonucleoside triphosphate to an RNA polymerase II transcribing
complex, with base pairing to the template DNA, was revealed by X-ray
crystallography. Binding of a mismatched nucleoside triphosphate was also
detected, but in an adjacent site, inverted with respect to the correctly paired
nucleotide. The results are consistent with a two-step mechanism of nucleotide
selection, with initial binding to an entry (E) site beneath the active center
in an inverted orientation, followed by rotation into the nucleotide addition
(A) site for pairing with the template DNA. This mechanism is unrelated to that
of single subunit RNA polymerases and so defines a new paradigm for the large,
multisubunit enzymes. Additional findings from these studies include a third
nucleotide binding site that may define the length of backtracked RNA; DNA
double helix unwinding in advance of the polymerase active center; and extension
of the diffraction limit of RNA polymerase II crystals to 2.3 A.
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Figure 2.
Figure 2. Downstream End of the DNA-RNA Hybrid in
Transcribing Complex Structures, Showing Occupancy of the A and
E Sites(A) Transcribing complex with matched NTP (UTP) in the A
site.(B) Transcribing complex with mismatched NTP (ATP) in the E
site. Views are the same as in Figure 1. DNA is blue, RNA is
red, and NTPs are in yellow. Mg ions are shown as magenta
spheres.
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Figure 5.
Figure 5. Substrate Entry to Active Center Regions of
Single and Multisubunit PolymerasesSolvent-accessible surfaces
for transcribing complexes of (A) pol II and (B) T7 RNA
polymerase (PDB 1H38) are shown, in a “front” view of pol II
(Cramer et al., 2000) and corresponding view of the T7 enzyme
(aligned on the sugar-phosphate backbone of the DNA-RNA hybrid)
(Tahirov et al., 2002), with the front portion of the proteins
cut away to reveal the DNA-RNA hybrid (DNA blue, RNA red). A
mismatched NTP bound to pol II as in Figure 2D is shown in pink.
The direction of substrate entry to the active center is
indicated by a black arrow.
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The above figures are
reprinted
by permission from Cell Press:
Cell
(2004,
119,
481-489)
copyright 2004.
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