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PDBsum entry 2k3o
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Structural protein
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PDB id
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2k3o
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References listed in PDB file
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Key reference
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Title
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Solution structure of eggcase silk protein and its implications for silk fiber formation.
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Authors
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Z.Lin,
W.Huang,
J.Zhang,
J.S.Fan,
D.Yang.
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Ref.
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Proc Natl Acad Sci U S A, 2009,
106,
8906-8911.
[DOI no: ]
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PubMed id
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Abstract
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Spider silks are renowned for their excellent mechanical properties and
biomimetic and industrial potentials. They are formed from the natural refolding
of water-soluble fibroins with alpha-helical and random coil structures in silk
glands into insoluble fibers with mainly beta-structures. The structures of the
fibroins at atomic resolution and silk formation mechanism remain largely
unknown. Here, we report the 3D structures of individual domains of a
approximately 366-kDa eggcase silk protein that consists of 20 identical type 1
repetitive domains, one type 2 repetitive domain, and conserved nonrepetitive N-
and C-terminal domains. The structures of the individual domains in solution
were determined by using NMR techniques. The domain interactions were
investigated by NMR and dynamic light-scattering techniques. The formation of
micelles and macroscopic fibers from the domains was examined by electron
microscopy. We find that either of the terminal domains covalently linked with
at least one repetitive domain spontaneously forms micelle-like structures and
can be further transformed into fibers at >/=37 degrees C and a protein
concentration of >0.1 wt%. Our biophysical and biochemical experiments
indicate that the less hydrophilic terminal domains initiate the assembly of the
proteins and form the outer layer of the micelles whereas the more hydrophilic
repetitive domains are embedded inside to ensure the formation of the
micelle-like structures that are the essential intermediates in silk formation.
Our results establish the roles of individual silk protein domains in fiber
formation and provide the basis for designing miniature fibroins for producing
artificial silks.
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Figure 2.
Solution structures of TuSp1 domains. Ribbon drawing of the
lowest-energy conformers of NTD (A), RP1 (B), RP2 (C), and CTD
(D). Hydrophobic and charged surface of NTD (E), RP1 (F), RP2
(G), and CTD (H). Unstructured regions are not shown. Color code
is yellow for hydrophobic, blue for positive charges, red for
negative charges, and white for neutral surface. Hydrophobic
patches on the surfaces are circled in black.
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Figure 4.
Models of TuSp1 micelles. (A) NRP/RPC micelle. The
N-terminal/C-terminal domains form the outer layer of the
micelle, whereas the repetitive domains with flexible long
unstructured linkers are randomly packed into the inner core of
the micelle. (B) Single full-length TuSp1 molecule with the N-
and the C-terminal domains interacting with each other. (C)
Full-length TuSp1 micelle. The sizes of micelles were estimated
based on our DLS and TEM results and the structures of NTD, RP1,
RP2, and CTD.
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Secondary reference #1
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Title
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Resonance assignments of a repeated domain of the egg case silk from nephila antipodiana.
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Authors
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Z.Lin,
W.Huang,
D.Yang.
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Ref.
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J Biomol Nmr, 2006,
36,
17.
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PubMed id
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Note In the PDB file this reference is
annotated as "TO BE PUBLISHED".
The citation details given above were identified by an automated
search of PubMed on title and author
names, giving a
perfect match.
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