6MPX

Twelve chloride ions induce formation and stabilize the NC1 hexamer of collagen IV assembled from transition state trimers

Summary for 6MPX

• Entry DOI: 10.2210/pdb6mpx/pdb
• Descriptor: fusion protein of non-collagenous domains of collagen type IV, CHLORIDE ION, SULFATE ION, ... (8 entities in total)
• Functional Keywords: structural protein
• Biological source: Homo sapiens (Human); More
• Total number of polymer chains: 1
• Total formula weight: 78197.83

Authors

Bauer, R.,Boudko, S.P.,Hudson, B.G. (deposition date: 2018-10-09, release date: 2019-04-03, Last modification date: 2024-10-16)

Primary citation

Pedchenko, V.,Bauer, R.,Pokidysheva, E.N.,Al-Shaer, A.,Forde, N.R.,Fidler, A.L.,Hudson, B.G.,Boudko, S.P.
A chloride ring is an ancient evolutionary innovation mediating the assembly of the collagen IV scaffold of basement membranes.
J.Biol.Chem., 294:7968-7981, 2019

PubMed Abstract: Collagen IV scaffold is a principal component of the basement membrane (BM), a specialized extracellular matrix that is essential for animal multicellularity and tissue evolution. Scaffold assembly begins with the trimerization of α-chains into protomers inside the cell, which then are secreted and undergo oligomerization outside the cell. For the ubiquitous scaffold composed of α1- and α2-chains, both intracellular and extracellular stages are mediated by the noncollagenous domain (NC1). The association of protomers is chloride-dependent, whereby chloride ions induce interactions of the protomers' trimeric NC1 domains leading to NC1 hexamer formation. Here, we investigated the mechanisms, kinetics, and functionality of the chloride ion-mediated protomer assembly by using a single-chain technology to produce a stable NC1 trimer comprising α1, α2, and α1 NC1 monomers. We observed that in the presence of chloride, the single-chain NC1-trimer self-assembles into a hexamer, for which the crystal structure was determined. We discovered that a chloride ring, comprising 12 ions, induces the assembly of and stabilizes the NC1 hexamer. Furthermore, we found that the chloride ring is evolutionarily conserved across all animals, first appearing in cnidarians. These findings reveal a fundamental role for the chloride ring in the assembly of collagen IV scaffolds of BMs, a critical event enabling tissue evolution and development. Moreover, the single-chain technology is foundational for generating trimeric NC1 domains of other α-chain compositions to investigate the α121, α345, and α565 collagen IV scaffolds and to develop therapies for managing Alport syndrome, Goodpasture's disease, and cancerous tumor growth.

PubMed: 30923125
DOI: 10.1074/jbc.RA119.007426

Experimental method

X-RAY DIFFRACTION (1.9 Å)