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Title: Crystal Structure of the Nephila clavipes Major Ampullate Spidroin 1A N-terminal Domain Reveals Plasticity at the Dimer Interface

Journal Article · · Journal of Biological Chemistry
 [1];  [1];  [2];  [1]
  1. Medical Univ. of South Carolina, Charleston, SC (United States)
  2. Clemson Univ., SC (United States)
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Spider dragline silk is a natural polymer harboring unique physical and biochemical properties that make it an ideal biomaterial. Artificial silk production requires an understanding of the in vivo mechanisms spiders use to convert soluble proteins, called spidroins, into insoluble fibers. Controlled dimerization of the spidroin N-terminal domain (NTD) is crucial to this process. In this paper, we report the crystal structure of the Nephila clavipes major ampullate spidroin NTD dimer. Comparison of our N. clavipes NTD structure with previously determined Euprosthenops australis NTD structures reveals subtle conformational alterations that lead to differences in how the subunits are arranged at the dimer interface. We observe a subset of contacts that are specific to each ortholog, as well as a substantial increase in asymmetry in the interactions observed at the N. clavipes NTD dimer interface. These asymmetric interactions include novel intermolecular salt bridges that provide new insights into the mechanism of NTD dimerization. We also observe a unique intramolecular “handshake” interaction between two conserved acidic residues that our data suggest adds an additional layer of complexity to the pH-sensitive relay mechanism for NTD dimerization. The results of a panel of tryptophan fluorescence dimerization assays probing the importance of these interactions support our structural observations. Based on our findings, we propose that conformational selectivity and plasticity at the NTD dimer interface play a role in the pH-dependent transition of the NTD from monomer to stably associated dimer as the spidroin progresses through the silk extrusion duct.

Research Organization:
Argonne National Laboratory (ANL), Argonne, IL (United States). Advanced Photon Source (APS)
Sponsoring Organization:
USDOE Office of Science (SC), Basic Energy Sciences (BES); National Institute of General Medical Sciences (NIGMS); National Institutes of Health (NIH); Office of Research Infrastructure Programs (ORIP)
Grant/Contract Number:
W-31-109-ENG-38; P41 GM103403; S10 RR029205; AC02-06CH11357; S10 RR027139-01
OSTI ID:
1328789
Journal Information:
Journal of Biological Chemistry, Vol. 291, Issue 36; ISSN 0021-9258
Publisher:
American Society for Biochemistry and Molecular BiologyCopyright Statement
Country of Publication:
United States
Language:
ENGLISH
Citation Metrics:
Cited by: 14 works
Citation information provided by
Web of Science

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Cited By (7)

Experimental Methods for Characterizing the Secondary Structure and Thermal Properties of Silk Proteins journal August 2018
Efficient protein production inspired by how spiders make silk journal May 2017
Methionine in a protein hydrophobic core drives tight interactions required for assembly of spider silk journal September 2019
Conservation of folding and association within a family of spidroin N-terminal domains journal December 2017
Structure of the N-terminal domain of Euprosthenops australis dragline silk suggests that conversion of spidroin dope to spider silk involves a conserved asymmetric dimer intermediate journal June 2019
Structure of the N-terminal domain of Euprosthenops australis dragline silk suggests that conversion of spidroin dope to spider silk involves a conserved asymmetric dimer intermediate text January 2019
Advances in Plant-Derived Scaffold Proteins journal February 2020

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Related Subjects

59 BASIC BIOLOGICAL SCIENCES
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
crystal structure
dimerization
protein self-assembly
protein structure
structural biology
structure-function
x-ray crystallography
MaSp1A
spidroin
spider silk
structural plasticity
Nephila clavipes