The Glaucoma-Associated Olfactomedin Domain of Myocilin Forms Polymorphic Fibrils That Are Constrained by Partial Unfolding and Peptide Sequence
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- 作者：Shannon E. Hill ; Rebecca K. Donegan ; Raquel L. Lieberman
- 关键词：TM ; trabecular meshwork ; ER ; endoplasmic reticulum ; ThT ; thioflavin T ; AFM ; atomic force microscopy ; ANS ; anilinonaphthalene-1-sulfonate ; FTIR ; Fourier transform infrared spectroscopy ; TEV ; tobacco etch virus
- 刊名：Journal of Molecular Biology
- 出版年：20 February, 2014
- 年：2014
- 卷：426
- 期：4
- 页码：921-935
- 全文大小：2259 K
文摘
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.