6TV5

NMR structure of N-terminal domain from A. argentata tubuliform spidroin (TuSp) at pH 5.5

Summary for 6TV5

• Entry DOI: 10.2210/pdb6tv5/pdb
• NMR Information: BMRB: 34473
• Descriptor: Tubuliform spidroin 1 (1 entity in total)
• Functional Keywords: spidroin, n-terminal domain, spidersilk, structural protein
• Biological source: Argiope argentata
• Total number of polymer chains: 2
• Total formula weight: 28110.89

Authors

Fridmanis, J.,Jaudzems, K. (deposition date: 2020-01-09, release date: 2021-01-27, Last modification date: 2023-06-14)

Primary citation

Sede, M.,Fridmanis, J.,Otikovs, M.,Johansson, J.,Rising, A.,Kronqvist, N.,Jaudzems, K.
Solution Structure of Tubuliform Spidroin N-Terminal Domain and Implications for pH Dependent Dimerization.
Front Mol Biosci, 9:936887-936887, 2022

PubMed Abstract: The spidroin N-terminal domain (NT) is responsible for high solubility and pH-dependent assembly of spider silk proteins during storage and fiber formation, respectively. It forms a monomeric five-helix bundle at neutral pH and dimerizes at lowered pH, thereby firmly interconnecting the spidroins. Mechanistic studies with the NTs from major ampullate, minor ampullate, and flagelliform spidroins (MaSp, MiSp, and FlSp) have shown that the pH dependency is conserved between different silk types, although the residues that mediate this process can differ. Here we study the tubuliform spidroin (TuSp) NT from , which lacks several well conserved residues involved in the dimerization of other NTs. We solve its structure at low pH revealing an antiparallel dimer of two five-α-helix bundles, which contrasts with a previously determined TuSp NT monomer structure. Further, we study a set of mutants and find that the residues participating in the protonation events during dimerization are different from MaSp and MiSp NT. Charge reversal of one of these residues (R117 in TuSp) results in significantly altered electrostatic interactions between monomer subunits. Altogether, the structure and mutant studies suggest that TuSp NT monomers assemble by elimination of intramolecular repulsive charge interactions, which could lead to slight tilting of α-helices.

PubMed: 35775078
DOI: 10.3389/fmolb.2022.936887

Experimental method

SOLUTION NMR