Early Events in the Amyloid Formation of the A546T Mutant of Transforming Growth Factor β-Induced Protein in Corneal Dystrophies Compared to the Nonfibrillating R555W and R555Q Mutants

Biochemistry. 2015 Sep 15;54(36):5546-56. doi: 10.1021/acs.biochem.5b00473. Epub 2015 Sep 2.

Abstract

The human transforming growth factor β-induced protein (TGFBIp) is involved in several types of corneal dystrophies where protein aggregation and amyloid fibril formation severely impair vision. Most disease-causing mutations are located in the last of four homologous fasciclin-1 (FAS1) domains of the protein, and it has been shown that when isolated, the fourth FAS1 domain (FAS1-4) mimics the behavior of full-length TGFBIp. In this study, we use molecular dynamics simulations and principal component analysis to study the wild-type FAS1-4 domain along with three disease-causing mutations (R555W, R555Q, and A546T) to decipher any internal difference in dynamical properties of the domains that may explain their varied stabilities and aggregation properties. In addition, we use a protein-protein docking method in combination with chemical cross-linking experiments and mass spectrometry of the cross-linked species to obtain information about interaction faces between identical FAS1-4 domains. The results show that the pathogenic mutations A546T and R555W affect the packing in the hydrophobic core of FAS1-4 in different directions. We further show that the FAS1-4 monomers associate using their β-rich regions, consistent with peptides observed to be part of the amyloid fibril core in lattice corneal dystrophy patients.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amyloid / chemistry*
  • Amyloid / genetics
  • Chromatography, Liquid
  • Computer Simulation
  • Corneal Dystrophies, Hereditary / genetics*
  • Cross-Linking Reagents / chemistry
  • Extracellular Matrix Proteins / chemistry*
  • Extracellular Matrix Proteins / genetics
  • Hydrophobic and Hydrophilic Interactions
  • Molecular Dynamics Simulation
  • Mutation
  • Succinimides / chemistry
  • Tandem Mass Spectrometry
  • Transforming Growth Factor beta / chemistry*
  • Transforming Growth Factor beta / genetics

Substances

  • Amyloid
  • Cross-Linking Reagents
  • Extracellular Matrix Proteins
  • Succinimides
  • Transforming Growth Factor beta
  • betaIG-H3 protein
  • bis(sulfosuccinimidyl)suberate

Supplementary concepts

  • Corneal Dystrophy, Lattice Type IIIA
  • Corneal dystrophy, Thiel-Behnke type
  • Groenouw type I corneal dystrophy