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PDBsum entry 2c4b
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Fusion protein
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PDB id
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2c4b
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References listed in PDB file
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Key reference
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Title
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Barnase fusion as a tool to determine the crystal structure of the small disulfide-Rich protein mcoeeti.
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Authors
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H.H.Niemann,
H.U.Schmoldt,
A.Wentzel,
H.Kolmar,
D.W.Heinz.
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Ref.
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J Mol Biol, 2006,
356,
1-8.
[DOI no: ]
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PubMed id
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Abstract
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We present a fusion system suited to determine the crystal structure of small
disulfide-rich proteins. McoEeTI, a hybrid inhibitor cystine knot microprotein,
was produced as a soluble fusion to a catalytically inactive variant of the
RNAse barnase in Escherichia coli. Functioning as a versatile tag, barnase
facilitated purification, crystallization and high-resolution structure
determination. Flexibility of the linker region allows for different relative
orientations of barnase and the fusion partner in two crystallographically
independent molecules and may thereby facilitate crystal packing. Nevertheless,
the linker region is well ordered in both molecules. This system may prove more
generally useful to determine the crystal structure of peptides and small
proteins.
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Figure 1.
Figure 1. Structure of the barnase-McoEeTI fusion protein.
Overlay of the two crystallographically independent molecules.
Chain A, barnase in blue and McoEeTI in cyan; chain B, barnase
in red and McoEeTI in orange. The four residue linker is in
light green or yellow. The overlay was performed on barnase,
highlighting the rigid body rotation of the fusion partners
relative to one another. The view is straight down the axis of
rotation (shown as boxed cross) as defined by DYNDOM.13
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Figure 2.
Figure 2. The linker between barnase and McoEeTI is well
ordered. (a) Water molecules with very low B-factors bridge
barnase, the linker and McoEeTI. Residues from barnase (Gln15 to
His18) are shown with carbon atoms in purple, Ser113 from the
linker in orange and Val116 and Ala132 from McoEeTI with carbon
atoms in cyan. Hydrogen bonds from water molecules 1, 2, 3 and 5
are shown as broken green lines. (b) Plot of the main chain
B-value by residue. The linker residues 111-114 (SSSM) have low
B-values. Linker residues are indicated by a black bar.
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The above figures are
reprinted
by permission from Elsevier:
J Mol Biol
(2006,
356,
1-8)
copyright 2006.
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