Early Events in the Amyloid Formation of the A546T Mutant of Transforming Growth Factor Beta Induced Protein (TGFBIp) in Corneal Dystrophies Compared to the Non-Fibrillating R555W and R555Q Mutants

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The human transforming growth factor beta induced protein (TGFBIp) is involved in several types of corneal dystrophies where protein aggregation and amyloid fibril formation severely impairs 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.

Original languageEnglish
JournalBiochemistry
Volume54
Issue36
Pages (from-to)55546-5556
Number of pages11
ISSN0006-2960
DOIs
Publication statusPublished - 25 Aug 2015

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