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PDBsum entry 2bjv
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Transcription
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PDB id
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2bjv
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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 insights into the activity of enhancer-Binding proteins.
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Authors
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M.Rappas,
J.Schumacher,
F.Beuron,
H.Niwa,
P.Bordes,
S.Wigneshweraraj,
C.A.Keetch,
C.V.Robinson,
M.Buck,
X.Zhang.
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Ref.
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Science, 2005,
307,
1972-1975.
[DOI no: ]
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PubMed id
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Abstract
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Activators of bacterial sigma54-RNA polymerase holoenzyme are mechanochemical
proteins that use adenosine triphosphate (ATP) hydrolysis to activate
transcription. We have determined by cryogenic electron microscopy (cryo-EM) a
20 angstrom resolution structure of an activator, phage shock protein F
[PspF(1-275)], which is bound to an ATP transition state analog in complex with
its basal factor, sigma54. By fitting the crystal structure of PspF(1-275) at
1.75 angstroms into the EM map, we identified two loops involved in binding
sigma54. Comparing enhancer-binding structures in different nucleotide states
and mutational analysis led us to propose nucleotide-dependent conformational
changes that free the loops for association with sigma54.
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Figure 2.
Fig. 2. Crystal structure of PspF[(1-275)]. The P6[5]  hexamer of
PspF[(1-275)] is shown as viewed down the sixfold axis. Both
/ß (green) and -helical domains
(pink) of one monomer are contoured with dashed lines. The
nucleotide-binding pocket is highlighted in yellow and is
located in the cleft between the /ß and -helical domain
at the interface with the adjacent monomer. N- and C-termini of
two adjacent monomers are also shown. Color coding is as
follows: blue, helices; red, central ß sheet; orange, L1;
and green, L2. The tip of the highlighted L1 is shown as a
dotted line because residues 82 to 89 were not resolved in our
crystal structure.
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Figure 3.
Fig. 3. Fitting of the PspF[(1-275)] crystal structure into the
EM electron density map of the PspF[(1-275)]-ADP.AlF[x]-  54
complex. (A) The front view of the EM density is colored
transparent gray and the PspF[(1-275)] crystal structure has a
blue ribbon representation. The fitting of the -helical domain
into one "claw" of the hexameric ring is highlighted; the
densities connecting PspF[(1-275)] to 54 are indicated
by red arrows. (B) Cross-eye stereo view of the fitting of one
pair of L1 and L2 loops into the connecting densities; the tip
of L1 is shown as a dotted line because residues 82 to 89 are
not resolved. When positioned in the densities, the loops extend
upward almost at a right angle to the plane of the hexamer.
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The above figures are
reprinted
by permission from the AAAs:
Science
(2005,
307,
1972-1975)
copyright 2005.
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