|Title||The glaucoma-associated olfactomedin domain of myocilin forms polymorphic fibrils that are constrained by partial unfolding and peptide sequence.|
|Publication Type||Journal Article|
|Year of Publication||2014|
|Authors||Hill, SE, Donegan, RK, Lieberman, RL|
|Journal||J Mol Biol|
|Date Published||2014 Feb 20|
|Keywords||Amino Acid Sequence, Amyloid, Circular Dichroism, Cytoskeletal Proteins, Extracellular Matrix Proteins, Eye Proteins, Glaucoma, Glycoproteins, Humans, Hydrogen-Ion Concentration, Molecular Sequence Data, Protein Folding, Protein Structure, Tertiary, Sodium Chloride|
The glaucoma-associated olfactomedin domain of myocilin (myoc-OLF) is a recent addition to the growing list of disease-associated amyloidogenic proteins. Inherited, disease-causing myocilin variants aggregate intracellularly instead of being secreted to the trabecular meshwork, which is a scenario toxic to trabecular meshwork cells and leads to early onset of ocular hypertension, the major risk factor for glaucoma. Here we systematically structurally and biophysically dissected myoc-OLF to better understand its amyloidogenesis. Under mildly destabilizing conditions, wild-type myoc-OLF adopts non-native structures that readily fibrillize when incubated at a temperature just below the transition for tertiary unfolding. With buffers at physiological pH, two main endpoint fibril morphologies are observed: (a) straight fibrils common to many amyloids and (b) unique micron-length, ~300 nm or larger diameter, species that lasso oligomers, which also exhibit classical spectroscopic amyloid signatures. Three disease-causing variants investigated herein exhibit non-native tertiary structures under physiological conditions, leading to a variety of growth rates and a fibril morphologies. In particular, the well-documented D380A variant, which lacks calcium, forms large circular fibrils. Two amyloid-forming peptide stretches have been identified, one for each of the main fibril morphologies observed. Our study places myoc-OLF within the larger landscape of the amylome and provides insight into the diversity of myoc-OLF aggregation that plays a role in glaucoma pathogenesis.
|Alternate Journal||J. Mol. Biol.|
|PubMed Central ID||PMC3946817|
|Grant List||R01 EY021205 / EY / NEI NIH HHS / United States |
R01EY021205 / EY / NEI NIH HHS / United States
The glaucoma-associated olfactomedin domain of myocilin forms polymorphic fibrils that are constrained by partial unfolding and peptide sequence.
Submitted by enguyen7 on December 30, 2015 - 10:38am