PDBsum entry 2k3o

Structural protein

PDB id: 2k3o

Contents

Protein chain

129 a.a. *

* Residue conservation analysis

PDB id:

2k3o

Name:

Structural protein

Title:

Solution structure of the type 2 repetitive domain (tusp1-rp2) of the egg case silk from nephila antipodiana

Structure:

Tusp1. Chain: a. Fragment: last repeated domain, rp2 (unp residues 186-314). Synonym: egg case silk. Engineered: yes

Source:

Nephila antipodiana. Batik golden web spider. Organism_taxid: 171624. Gene: eggcase silk gene. Expressed in: escherichia coli. Expression_system_taxid: 562.

NMR struc:

10 models

Authors:

Z.Lin,W.Huang,J.Fan,D.Yang

Key ref:

Z.Lin et al. (2009). Solution structure of eggcase silk protein and its implications for silk fiber formation. Proc Natl Acad Sci U S A, 106, 8906-8911. PubMed id: 19458259 DOI: 10.1073/pnas.0813255106

Date:

14-May-08 Release date: 02-Jun-09

Protein chain

Q1I128  (Q1I128_9ARAC) -  TuSp1 (Fragment) from Trichonephila antipodiana

Seq: 465 a.a.

Struc: 129 a.a.

Enzyme reactions

• Enzyme class: E.C.?

DOI no: 10.1073/pnas.0813255106

Proc Natl Acad Sci U S A 106:8906-8911 (2009)

PubMed id: 19458259

Solution structure of eggcase silk protein and its implications for silk fiber formation.

Z.Lin, W.Huang, J.Zhang, J.S.Fan, D.Yang.

ABSTRACT

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.

Selected figure(s)

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.

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.

Figures were selected by an automated process.