Predicted Loop Regions Promote Aggregation: A Study of Amyloidogenic Domains in the Functional Amyloid FapC
| Autor: | Brian S. Vad, Jan Skov Pedersen, Andreas Bøggild, Madhu Nagaraj, Mumdooh Ahmed, Jeppe Lyngsø, Anne Fillipsen, Daniel E. Otzen, Ümit Akbey |
|---|---|
| Rok vydání: | 2020 |
| Předmět: |
Amyloid
Mutant Nucleation Amyloidogenic Proteins Fibril polymorphism Protein Aggregates 03 medical and health sciences 0302 clinical medicine Bacterial Proteins Structural Biology Pseudomonas fibrillation mechanism Amino Acid Sequence Molecular Biology 030304 developmental biology solid state NMR 0303 health sciences Small-angle X-ray scattering Chemistry SAXS functional amyloid fibril FapC Phenotype Mutation Biophysics 030217 neurology & neurosurgery |
| Zdroj: | Nagaraj, M, Ahmed, M, Lyngsø, J, Vad, B S, Bøggild, A, Fillipsen, A, Pedersen, J S, Otzen, D E & Akbey, Ü 2020, ' Predicted Loop Regions Promote Aggregation : A Study of Amyloidogenic Domains in the Functional Amyloid FapC ', Journal of Molecular Biology, vol. 432, no. 7, pp. 2232-2252 . https://doi.org/10.1016/j.jmb.2020.01.044 |
| ISSN: | 0022-2836 |
| Popis: | Protein fibrillation is traditionally associated with misfolding, loss of functional phenotype, and gain of toxicity in neurodegenerative diseases. However, many organisms exploit fibrils in the form of functional amyloids (FA), as seen in bacteria, such as E. coli, Salmonella, Bacillus, and Pseudomonas. Here, we provide structural information and mechanistic data for fibrillation of the smallest amyloidogenic truncation unit along with the full-length version (FL) of the major amyloid protein FapC from Pseudomonas, predicted to consist of three β-hairpin-forming imperfect repeats separated by disordered regions. Using a series of truncation mutants, we establish that the putative loops (linkers) increase the rate of aggregation. The minimal aggregation unit consisting of a single repeat with flanking disordered regions (R3C) aggregates in a pathway dominated by secondary nucleation, in contrast to the primary nucleation favored by full-length (FL) FapC. SAXS on FapC FL, R3C, and remaining truncation constructs resolves two major coexisting species in the fibrillation process, namely pre-fibrillar loosely aggregated monomers, and cylindrical, elliptical cross-section fibrils. Solid-state NMR spectra identified rigid parts of the FapC fibril. We assigned Cα–Cβ chemical shifts, indicative of a predominant β-sheet topology with some α-helix or loop chemical shifts. Our work emphasizes the complex nature of FapC fibrillation. In addition, we are able to deduce the importance of non-repeat regions (i.e., predicted loops), which enhance the amyloid protein aggregation and their influence on the polymorphism of the fibril architecture. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|
Full Text from ScienceDirect