Collagen IVα345 dysfunction in glomerular basement membrane diseases. II. Crystal structure of the α345 hexamer

Sergei P Boudko,Ryan Bauer,Sergei V Chetyrkin,Sergey Ivanov,Jarrod Smith,Paul A Voziyan,Billy G Hudson

doi:10.1016/j.jbc.2021.100591

Sergei P Boudko, Ryan Bauer + Show 5 more

Open Access

https://doi.org/10.1016/j.jbc.2021.100591

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Abstract

Our recent work identified a genetic variant of the α345 hexamer of the collagen IV scaffold that is present in patients with glomerular basement membrane diseases, Goodpasture’s disease (GP) and Alport syndrome (AS), and phenocopies of AS in knock-in mice. To understand the context of this “Zurich” variant, an 8-amino acid appendage, we developed a construct of the WT α345 hexamer using the single-chain NC1 trimer technology, which allowed us to solve a crystal structure of this key connection module. The α345 hexamer structure revealed a ring of 12 chloride ions at the trimer–trimer interface, analogous to the collagen α121 hexamer, and the location of the 170 AS variants. The hexamer surface is marked by multiple pores and crevices that are potentially accessible to small molecules. Loop-crevice-loop features constitute bioactive sites, where pathogenic pathways converge that are linked to AS and GP, and, potentially, diabetic nephropathy. In Pedchenko et al., we demonstrate that these sites exhibit conformational plasticity, a dynamic property underlying assembly of bioactive sites and hexamer dysfunction. The α345 hexamer structure is a platform to decipher how variants cause AS and how hypoepitopes can be triggered, causing GP. Furthermore, the bioactive sites, along with the pores and crevices on the hexamer surface, are prospective targets for therapeutic interventions.

Highlights

Prominent diseases of the glomerular basement membrane (GBM), a specialized form of the extracellular matrix, are diabetic nephropathy (DN), Alport syndrome (AS), and Goodpasture’s disease (GP)
We previously determined the equimolar composition of α3, α4, and α5 chains in the α345 hexamers isolated from the GBM [7] (Fig. 1A)
The crystal structure of the hexamer revealed a ring of 12 chloride ions that, together with up to six sulfilimine bonds, stabilizes the hexamer structure (Fig. 12A)

Summary

RESEARCH ARTICLE

Collagen IVα345 dysfunction in glomerular basement membrane diseases. Boudko1,2,3,*,‡ , Ryan Bauer1,2 , Sergei V. Hudson1,2,3,4,5,6,7,8,‡ From the 1Department of Medicine, Division of Nephrology and Hypertension, and 2Center for Matrix Biology, Vanderbilt University Medical Center, Nashville, Tennessee, USA; 3Department of Biochemistry, Center for Structural Biology, Vanderbilt University, Nashville, Tennessee, USA; 4Aspirnaut, Vanderbilt University Medical Center, Nashville, Tennessee, USA; 5Department of Pathology, Microbiology and Immunology, Vanderbilt University Medical Center, Nashville, Tennessee, USA; and 6Department of Cell and Developmental Biology; 7Institute of Chemical Biology; and 8Vanderbilt-Ingram Cancer Center, Vanderbilt University, Nashville, Tennessee, USA

Edited by Gerald Hart

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